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July Discussion Archive

July 31 2005 - 02:00 UTC

The tropical wave passing over Hispaniola is still being monitored for signs of organization. Yesterday evening, the forecast took the bulk of low level energy north of Hispaniola. Over the past 24 hours, the low level circulation spotted yesterday has moved into the Dominican Republic, however. Interaction with land will inhibit tropical development another 24 hours. Notwithstanding, the northern end of the sharp wave axis is north of Puerto Rico. In addition to land interaction, the upper low to the northwest of the wave axis is still generating 30-40 knots of shear. All global model guidance dissipates this upper low within 24-48 hours. The available model guidance can be backed up by water vapor trends, which clearly show the upper low weakening ever so slightly. Upper level winds will begin to relax over the southwest Atlantic once this feature is no longer present. Otherwise, atmospheric conditions will remain hostile for tropical cyclogenesis for the next 24-48 hours. The SHIPS intensity model has strengthened 92L significantly for several runs and that has not changed. One should know that the system under investigation must be initalized in the model as a tropical depression in order for it to run properly. Therefore, the intensity forecasts should be taken with a grain of salt, but they should not be dismissed entirely. Development is no longer expected within the next 24-36 hours, but it is still considered quite possible beyond that period.

Global model tracks are in much better agreement than they were 24 hours ago. First, a few models do take some of the wave's energy westward into the eastern Gulf of Mexico, and that does seem possible given the current low level steering flow and the way in which the wave is tangled up over Hispaniola at the moment. But all of the models take the bulk of wave energy east and north of Florida. The GFS model initially took a weak inverted wave towards southern Florida and the Florida Staights a few days ago. Yesterday, the model began to develop the northern end of the wave followed by taking it out to sea towards Bermuda. Today, the 18Z GFS run continues to show development of the northern end of the wave axis just east of the northern Bahamas. By Day 6, the model shows a broad surface low east-southeast of Cape Hatteras before it is pushed out to sea by an approaching upper trough. The NOGAPS model has been flip-flopping between Florida and the Carolina for several days. Yesterday, the model took a broad area of low pressure westward followed by recurvature along the west coast of the Florida Peninsula. Today's 12Z run now shows the majority of low to mid level energy over the northern Bahamas by Day 4. By Day 6, the model indicates a closed surface circulation with 20-25 knot winds moving over Cape Hatteras. The 18Z run of the NOGAPS is not available. The ECMWF has also shifted. There was some question whether the model took the wave into the Gulf or up the East Coast the last couple days, but today it's obvious. by Day 5, an 850MB low is centered over the northern Bahamas. By Day 6, a low is still over the Bahamas, but a northern piece of the wave splits and begins to develop near Bermuda. The Canadian model is the easternmost outlier. The CMC develops a tropical storm along the northern end of the wave and takes it just west of Bermuda before going out to sea. Meanwhile, the UKMET is still, by far, the most consistent model thus far. The 12Z run takes an 850MB vorticity into the northern Bahamas by Day 5 while hinting at surface low development. The track through Day 5 suggests a continued path toward the Carolinas. The Day 6 forecast was not available.

While 92L INVEST still looks like a mess, the potential for development in a few days should not be ignored. All global model guidance indicates that the main wave axis will be well to the north of Hispaniola in a couple days. Furthermore, the upper level low, which is responsible for the hostile upper wind regime, is forecast to weaken significantly or dissipate altogether within 48-72 hours. The two main factors that have been inhibiting development for the last several days should be nonexistant by 72 hours. Furthermore, global models continue to show potential surface reflection south of the Carolinas by Day 5. Other than the SHIPS intensity forecast, which should be taken with a grain of salt, there are no indications of an East Coast hurricane threat. However, it is very possible for Tropical Depression or Tropical Storm formation within 3-6 days. Even if a classified tropical cyclone does not form, the low pressure area could affect the weather along the East Coast, and regional National Weather Service offices will tweak their forecasts accordingly.

93L INVEST was left for dead once it collapsed in the eastern Atlantic, but it has since come to life. Convection has increased significantly over thre last 24 hours, and a mid level circulation is also visible on satellite imagery. Low level inflow is lacking, however. 93L is moving westward at a low latitude, and the upper low affecting 92L INVEST is not a factor in regards to this system. In fact, a deep layer ridge is aloft, and upper level winds are favorable for intensification. Nevertheless, there is a lot of dry air over the entire Caribbean Sea. No global models are developing 93L yet. Some slow development is possible over the next few days, and a TPC reconnaissance aircraft is scheduled to invesitgate this area tomorrow afternoon.

In the eastern Pacific, a broad low near 120斡 has a slight chance to develop within the next 36 hours before being sheared apart. This low will not affect any landmasses. Meanwhile, a much larger low pressure system near 10摸/100斡 has some potential to develop within 3-5 days. This system is not expected to affect land either.

In the western Pacific, Tropical Storm Washi (08W) is forecast to hit northern Vietnam with 40-45 knot winds in 12-24 hours. Meanwhile, a Tropical Cyclone Formation Alert has been issued for the tropical disturbance just north of Yap. This disturbance has the potential to become a tropical storm or typhoon over the next few days. In the medium range, northeast China or Japan could be threatened. In addition, global models suggest the development of yet another tropical cyclone in the mid-latitudes near 25摸/150慟 in 3-6 days. This progged tropical cylone will also have to be monitored as it could also pose a threat to Japan.

July 30 2005 - 02:00 UTC

92L INVEST, a tropical wave passing over the northeast Caribbean Sea, continues to show signs of gradual organization. One has to consider its progression over the last 48-72 hours. Over the last 6-12 hours, low level banding features have become better defined, low level inflow in the southern semicircle has been on the increase, and a low to mid level circulation has been spotted east-southeast of Puerto Rico on radar and satellite imagery. the only feature inhibiting development is the upper level low south-southwest of Bermuda. The upper low is generating 30-40 knot upper level winds over the northern half of 92L. While the 500MB low has been moving westward in tandem with the wave, global models suggest that the distance between the two features will increase over the next few days. Conditions are expected to be relatively favorable for intensification over the western Atlantic and the Bahamas. The SHIPS intensity model continues to develop 92L into a minimal hurricane within five days. This model will be increasingly reliable once 92L becomes a depression; the wave has already escaped the aforementioned Saharan Air Layer. The main energy associated with the wave is not expected to continue westward into mountainous Hispaniola. The 12Z UKMET and CMC continue to suggest that the developing surface low will move north of Hispaniola, and current satellite imagery shows the majority of convection and the potential low level energy lifting into the western Atlantic this evening.

The expected track of 92L is still relatively uncertain. The 18Z NOGAPS seems bogus as it takes the low level circulation westward through Hispaniola and eastern Cuba before it shows recurvature along the Florida peninsula. This scenario wouldn't be so unlikely if the wave was weak and had no chance of development. The subtropical ridge does extend as far west as Florida in low level 700MB-850MB steering layer. The GFS has completely reversed its initial westerly track towards Florida and has since shifted closer to Bermuda as of 18Z. A track this far east seems unlikely as it appears to be downplaying the strength of the subtropical ridge in the low to mid levels; the model does not depict development. The Canadian model remains just east of the Carolinas while the UKMET outlines the potential threat to the Carolinas. The UKMET shows an 850MB vorticy passing east and north of Puerto Rico (slightly too far north in the short term) and entering the northern Bahamas by 72 hours. The model then projects a northerly track towards the Carolinas through 144 hours. The UKMET has been the most consistent model and it has been in the middle of the global model tracks thus far. Moreover, such a track seems fairly likely if the low were to deepen over the Bahamas as progged by the model. A significant weakness is still in place over the East Coast in the mid to upper levels. In conclusion, we still do not anticipate a track towards the Florida coast. The low is forecast to deepen into a Tropical Depression or Tropical Storm once over or near the southeast Bahamas followed by a turn towards the northwest within the next 72 hours. If this forecast were to verify, then 92L could pose a threat to the Carolinas. The only other scenario is more rapid recurvature as depicted by the CMC and GFS models, but that is not expected at this time. Again, the path of 92L is not certain and all interests in the Bahamas and southeast US from Florida northward to North Carolina are advised to monitor this system.

The remaining tropical waves east of the Lesser Antilles are showing no signs of development. Homegrown development near the coast of Florida or northwest Gulf of Mexico is not expected at this time.

July 29 2005 - 02:00 UTC

Tropical Storm Franklin continues to intensify. Satellite imagery indicates a much better convective symmetry and an improved outflow regime as it moves off to the northeast. This is occurring as a progressive trough begins to interact, helping to enhance a poleward outflow channel and thus amplifying the storm itself. Some additional increase in strength is lpossible over the next 12 hours, and Franklin could max out as high as 60KT before losing its tropical characteristics and merging with the trough.

The main focus today remains INVEST 92L, a tropical wave and associated 1013MB surface low near 17摸/57斡. This system has gradually become better organized today per satellite imagery; upper-level outflow is clear to the north and convection is more much consolidated near the center. Vast improvement is noted when compared to 36 hours ago, when it was barely more than a broad tropical wave with isolated convection and ingested dry air. The anticyclone aloft is centered a bit southwest of the center, so little outflow is noted on the southern quadrant. Several weak mid-level circulations are also detectable in satellite imagery, so in an absolute sense, organization is still somewhat lacking. Nonetheless, conditions are gradually becoming more conducive. The upper-level trough to the west is currently inducing moderate southwesterly shear upon the area. This feature will continue to be somewhat of a problem over the next day or so, but after that time is progged to slowly lift away. The Saharan Air Layer previously entrained in the circulation has decreased as well. Global model guidance suggests a favorable environment once in the Bahamas vicinity after Day 3 or so, after the trough makes way for conducive upper-level ridging. An aircraft reconaissance is scheduled to investigate 92L tomorrow, if necessary. Further development into Tropical Depression status is likely over the next 48 hours.

The future track of 92L is largely dependant on the strength and alignment of the subtropical ridge to the north. Over the next few days, the ridge should allow for a continued west-northwest motion, taking it just a hair north of the Leeward Islands and towards the Bahamas. Global model guidance is in strong agreement on this track, but there is a bit more divergence in the solutions the end of the forecast period. The NOGAPS model has been flip-flopping between a track towards Florida and the Carolinas. The 18Z run now depicts a weak surface low curving north near West Palm Beach, Florida, at Day 5 and hints of a Carolinas brush by Day 6. The GFS has also been very inconsistent. The last several runs have taken an inverted wave towards southern Florida. However, the 18Z run now splits the wave over the Bahamas; the northern half ejects northeast and out to sea while the southern half spreads west into Florida. The ECMWF, which has been the only model that clealry suggested a track towards the Gulf, is attempting to shift northward up the East Coast as of 12Z. Meanwhile, the UKMET and CMC have become bullish on tropical cyclogenesis just east of the Bahamas. Both models also suggest recurvature before the East Coast, and just east of the Outerbanks of North Carolina. The main assumption concerning the track is the idea of at least some development once north of Puerto Rico and east of the Bahamas. A more northerly track is favored due to the large weakness in the steering flow currently along the East Coast in the mid levels, and the lack of development shown by the GFS and NOGAPS models. All of the global models suggest that the subtropical ridge will temporarily strengthen just east of Florida, but a stronger tropical cyclone would have a slightly more poleward bias, and it would feel the effects of a mid level trough over the East Coast more than an inverted wave. If a notherly turn near the northern Bahamas does transpire, then the question will become whether the Carolinas will feel the directly effects of the tropical cyclone or if veers off to the northeast. Due to the Canadian model's rightward bias all season and the inability of the UKMET to lock onto a medium range track, it is quite possible that the Carolinas, more so North Carolina, could be at risk. It should be noted that some of these medium range ideas are hardly more than conjectures. If 92L fails to close off a surface circulation over the next 48 hours, then the end result very well could be a southerly track towards Florida.

The remaining waves in the central and eastern Atlantic have become very disorganized over the last 12-24 hours. There is little to no chance of development in the short term.

July 28 2005 - 22:00 UTC

Tropical Storm Franklin has made a bit of a comeback today. Convection has flared a bit closer to the center and the cloud pattern has become slightly better organized. An additional 5-10KT increase in strength is very possible before the storm becomes carried northward by an upper trough. On this projected track, the storm should stay well offshore the US east coast.

A large-amplitude tropical wave, INVEST 92L, and associated broad 1013MB low is approaching 50斡. The low is currently positioned on the southern end of the wave axis, however visible imagery depicts greater low-level curvature further north. Furthermore, dry Saharan Air is still wrapped within the wave, particularly on the northern side, which is keeping convective flare-ups to a minimum. Thus, the system still needs to consolidate more and enter a more unstable environment before development becomes an imminent concern. Having said this, conditions become increasingly more favorable closer to the Windward islands and all the way to the Bahamas. Oceanic heat content is high, coinciding with unseasonably warm sea-surface temperatures. Upper-level wind shear is on the low side, with the core westerly winds from the subtropical jet remaining well to the north. In fact, the latest CIMSS GOES-12 analysis indicates ridging is slowly increasing aloft the wave. Moreover, the influence of the Saharan Air Layer is lessening as it progresses further west. All of this data suggests that while the wave is far from being a classified tropical cyclone, further organization and increasing convection seems likely over the next few days. Given the extent of the environmental favorability where 92L is headed, a tropical depression cannot be ruled out within the next 48-60 hours.

INVEST 92L is moving generally west-northwestward. Global model guidance is rather converged on the projected track. The 12Z NOGAPS, UKMET, CMC, and ECMWF plus 18Z GFS all show a continued west-northwest motion through or just north of the Leeward Islands over the next 48 hours and then passing in the vicinity of the Bahamas by the end of the forecast period. Once near the Bahamas on Day Six, models vary on the precise alignment and strength of the ridge weakness over the eastern US and the ridge itself. The ECMWF, usually a reasonable medium-range model, takes the system all the way into the Gulf of Mexico by the middle of next week. Although it is somewhat of an outlier and no other model seems to show as intense of a ridge as the ECMWF depicts, it is worth noting the strong right bias in the model consensus for storms in this area during 2004 and early this season. The GFS slows it down in the Bahamas under supposedly collapsed steering currents, similar to what recently took place with Franklin the same area earlier last week, whereas the others show what seems to be a straight shot to somewhere along the southeast US coast beyond the runs' time frames. Development from this area is not a certainty, though the chance is very much there. IF this does consolidate and become a tropical cyclone, conditions should favor quicker intensification once in the Bahamas and we could be faced with a hurricane threat. "If" is the key word.

Behind INVEST 92L, another tropical wave and mid-level center is noted, dubbed INVEST 93L. This system looked very well organized for a brief time late last night but has since become weaker. First off, the wave is not high-amplitude like the one discussed above, thus making it more susceptible to unfavorable conditions. Convection is sporadic in nature and there are no signs of either a surface low or a ridge aloft. Although sea surface temperatures are warm, this system is experiencing increased shear from the upper-level anticyclone to the west. As this ridge continues to build aloft 92L, this hinderance may only worsen with time. Furthermore, 93L is under moderate Saharan Air Layer influence from the north and east. Global models are not aggressive on developing the storm; none show anything more than a weak low in the shadows of a stronger system over the next six days. It is possible that some slow development could occur once and if the system can achieve a low-level circulation, though even so, anything significant seems unlikely. The future track is a moot point given the low prospects, but if a storm were to develop it would likely follow west-northwestward on the heels of the wave discussed above.

Yet another area of convection has emerged off the coast of Africa, behind both aformentioned INVESTs. This has not yet been identified in association with a tropical wave, but is rather a result of the intertropical convergence zone. Today's runs of the GFS and NOGAPS indicate this will become a tropical cyclone in the forecast period as it too moves west-northwestward. No other model has yet shown any significant development, so there is not a convincing consensus at this time. One plus for this system is that it is at a relatively low latitude, which may prevent it from experiencing the core of the Saharan Air Layer. Since conditions are apparently not that unfavorable, this system will be monitored as it traverses the tropical Atlantic.

Some global models are hinting at increased low-level vorticity in the northern Gulf of Mexico on the tail end of a trough split in the next 4-5 days. None develop a true tropical cyclone, and any low that does form would probably have to work hard to make it to the surface, not to mention it would be a primarily baroclinic origination. This will too be watched, though nothing is expected at this time.

Two INVESTS in the West Pacific, one in the South China Sea and the other well east of the Philippines, have potential for further development over the next few days.

IWIC Worldwide Tropical Weather Discussion - July 27 2005 - 02:00 UTC

Tropical Storm Franklin just will not quit. Upper level westerly winds continue to expose the low level surface circulation, but convection always redevelops soon thereafter. Some fluctuations in intensity are possible over the next 24 hours before a second upper trough lifts Franklin northward and absorbs the TC. All model guidance takes the system north and away from Bermuda.

A high amplitude tropical wave and associated 1013MB low, now designated with the name 92L INVEST by the NAVY, is located near 10摸/42斡 . There are a lot of factors that support intensification. 92L has a well defined signature, sea surface temperatures are warm, and upper level winds are light. A deep layer ridge in the mid and upper levels is present from the coast of Africa westward to 50斡 in the central Atlantic. This deep layer ridge will retrograde westward with 92L, much like the same setup with tropical wave's Dennis and Emily. The 18Z run of the SHIPS intensity model brings 92L up to minimal hurricane strength by Day 5, which is when the system will be passing over the Lesser Antilles. However, none of the global models show significant tropical development over the next six days, and there is good reason for that. The Saharan Air Layer (SAL) is fully entrained into the weak surface low along the wave axis. The dry air entrainment is easily visible on eastern Atlantic water vapor imagery and CIMSS Meteosat-8 SAL imagery. Much of the atmosphere over the central Atlantic is fairly stable at the moment. Tropical cyclogenesis of 92L INVEST east of Puerto Rico is not anticipated. If the wave's excellent signature persists as it approaches 20摸 and 65斡-70斡, then we may have to watch for development near the Bahamas. This forecast is still subject to change, and interests in the Lesser Antilles should continue to monitor the progress of 92L. Should the SAL weaken more than expected, then formation could occur much quicker than forecast.

Another vigorous tropical wave has exited the coast of Africa, and it has also been classified 93L INVEST by the NAVY. Conditions are much more favorable for tropical cyclogenesis of 93L than 92L. Sea surface temperatures are equally conducive, but 93L is directly centered underneath the deep layer ridge. Furthermore, 93L does not have to contend with the Saharan Air Layer nearly as much. The first high amplitude wave can be considered the frontrunner, and it is clearing out all the dry air ahead of 93L. Convection has been numerous, but another 12-24 hours of persistence over the eastern Atlantic is warranted. Slow development into a Tropical Depression is possible over the next 24-48 hours. It is too early to determine the threat it could pose to the Lesser Antilles. Some of the global models are indicating that the upper trough that will steer the remant of Franklin will weaken the subtropical ridge, which could steer 93L north of the islands. However, the data as of 12Z is considered inconclusive.

A third tropical wave has entered the eastern Atlantic within the last 6 hours. This wave will also be monitored for signs of development.

The global models are also developing a low pressure area well east of Bermuda in the medium range. This low could be hybrid or nontropical in nature, however. This progged low will be monitored.

Tropical Storm Banyan (07W) is dissipating east-northeast of Tokyo, Japan.

A large, disorganized area of thunderstorm activity located north of New Guinea will be watched closely for development in the western Pacific. The NOGAPS and GFS lift this area northward and hint at tropical cyclone formation in the medium range.

July 26 2005 - 01:00 UTC

Tropical Storm Franklin is highly disorganized. The low level circulation center has been exposed for at least 24-36 hours due to westerly shear. Upper level conditions are expected to remain unfavorable over the next several days, and Franklin should dissipate relatively soon. However, the the eastern semicircle of Franklin is the most intense, and even if the LLCC passes just north of Bermuda, the island will still face the brunt of the storm. Furthermore, the center may come closer to the island than the official forecast track is indicating. Tropical depression force winds with gusts to tropical storm intensity along with occasional squalls should be expected.

Tropical Storm Gert made landfall near Tampico, Mexico, overnight and is now dissipating. The last official advisory on Tropical Depression Gert was issued at 11AM EDT.

The central and eastern Pacifc remain very quiet. There is not one disturbance that shows any potential of tropical cyclone development, nor does any global model suggest an increasing probability of formation within the next 6-7 days.

There are several tropical waves in the eastern Atlantic and western Africa that will have to be monitored for tropical cyclone formation in the medium range. None of the global models except the GFS develop any of these waves into a significant TC, but that is not unusual. It is quite possible that the 8th system of the 2005 season could form within the next 10 days; not too many breaks this year. The Lesser Antilles should continue to monitor these waves.

Tropical Storm Banyan (07W) is making landfall over southern Japan. Maximum sustained winds are 45 knots, which should not cause significant structural wind damage. However, heavy rainfall and potential flooding could be a problem over the next 36 hours and beyond that period for central and northern Japan.

The remainder of the western Pacific is quiet. The GFS model wants to develop a tropical storm south-southwest of the Northern Marianas within 5-6 days but there is no other model support at this time.

July 22 2005 - 18:00 UTC

Tropical Storm Franklin is now moving northward away from the Bahamas. The storm is gradually becoming better organized. The outflow regime is much better defined, especially to the south and north of the center, and convective banding features have likewised improved. The upper environment surrounding Franklin is becoming more favorable, which is allowing the storm to gain organization as it has today. The anticyclone to the southwest has slid further left while Franklin has moved further north; this increased distance has ceased the restriction and shearing on the southwest side of the storm. In fact, several global models amplify an anticyclone on top of Franklin itself over the next day or so before becoming intertwined with the trough. Given this probability plus low shear and warm Gulf stream waters, further strengthening is likely. Franklin has a good chance of becoming a minimal hurricane sometime this weekend.

Our opinion on the storm's future track has not changed much from yesterday. Franklin is currently along the left periphery of a ridge of high pressure, which is inducing straight southerly flow over the area. Strong westerlies are still streaming along 35摸 from the east coast to Bermuda's vicinity. This pattern, very clearly seen on the latest CIMSS 700-850MB steering level map, is not progged to change much over the next 72 hours. Therefore, Franklin will be guided further north over the next day or so followed by a curve to the east-northeast. Global models are in tight agreement on this general track, all of them keeping the storm well offshore the southeast US coast. The only models that still take the storm into Florida or linger it in its current spot are the tropical models. However, these models have very poor performance for tropical cyclones interacting with and near baroclinic features, which applies to nearly every storm above 20摸. Therefore, they are given little to no weight for this storm, and the fact that they are an outlier to every single reliable global model makes them seem even more skewed. The only way Franklin will curve back to the west is if it fully misses the connection with the trough. Since this is not offered in any of the models at this time, and based on the steering layers the storm will become too involved in the trough soon, such a scenario remains by far the least likely. Franklin is forecast to move towards sea or perhaps Bermuda as a minimal hurricane.

Other than Franklin, another tropical wave is generating strong masses of convection over the Yucatan Peninsula and adjacent waters. Visible satellite imagery depicts a possible low-level circulation developing just offshore the southern coastline of the eastern Yucatan. The strong anticyclonic flow noted yesterday has weakened, though this should regain defination once the system emerges into the southwest Gulf of Mexico. When this commences, conditions will be favorable for development. The shearing environment is expected to be low, especially with the anticyclone over the system which will act as a shield to any countering winds. Global models as a whole only show marginal development, no more than a weak tropical storm at face value. However keep in mind these models barely picked up on the systems that became Bret and Cindy a few weeks ago. The fact that there's 1)already an incipient disturbance in place, 2)moving into a favorable upper environment, and 3)models pick up on increased low-level vorticity, tropical cyclone development is a distinct possibility. Models currently take whatever shows up on the runs into northeastern Mexico or southern Texas by Day 4. There has been a slight trend to the east since yesterday, though it is this general area that has the best chance of landfall. The limit on intensification will be the lack of time over water, and thus if a tropical cyclone does develop as is expected, it would probably be no more than a tropical storm.

In the deep tropical Atlantic, several waves are traversing the region. However, conditions are not perfectly favorable for development, and none are showing any strong signs of organization at this time.

In the West Pacific, Tropical Storm Nalgae is weakening well east of Japan. Tropical Storm Banyan, on the other hand, is intensifying and expected to become a typhoon over the next 48-72 hours. This system bears watching in Japan, as several models take it there before the forecast period is over.

July 21 2005 - 21:00 UTC

A tropical low located just east of the Bahamas has shown increasing signs of organization and persistence over the last 24 hours. Visible floater imagery outlines a decent low to mid level circulation representation. TPC Aircraft Reconnaissance is flying into the disturbance to determine if a surface circulation has formed. If Recon does find a closed circulation, then advisories on Tropical Depression 6 or possibly even Tropical Storm Franklin could be initiated at 5PM EDT depending on the maximum sustained winds found. Even if Recon does not find a closed off circulation, tropical development is likely within the next 24 hours. The upper air environment is becoming increasingly favorable for tropical cyclogenesis. An upper level ridge is developing over the Delmarva Peninsula, which will protect the developing surface low from an upper trough near 30摸/60斡 increasing westerly winds. Furthermore, the aforementioned trough is being allowed to sink further south near 65斡 due to the positioning of an upper cyclone near 23摸/56斡. To the west of the area under investigation, a weak upper low in the eastern Gulf of Mexico is increasing the southerly flow that extends into the southeast United States. In short, all of these interacting upper level features are increasing the amount of upper level ridging off the East Coast. This pattern is somewhat similar to the pattern in which Hurricane Alex developed last season. However, Alex was caught underneath an upper ridge for several days, and the ridge enabled it to have more time to develop. This time around, the upper trough near 60斡 may steer the tropical cyclone to the northeast before another mid level steering ridge begins to slide into the western Atlantic from the central United States. With that being said, the low could rapidly develop into a moderate to strong tropical storm within 3-4 days. The SHIPS intensity model ramps up the low into a 60mph tropical storm by Day 4.

The tropical model suite will not perform with this system as well as it did with Hurricane Emily. Emily was trapped under a large subtropical ridge that did not breakdown. The tropical models can have decent verification when baroclinic (nontropical) steering features are not present; usually when the tropical cyclone is being steered by the strong low to mid level easterlies south of 25� and south of a strong subtropical ridge. There are too many baroclinic features involved with the steering off the East Coast right now. The 500MB trough near 60斡 should be the main steering factor based on global model guidance, which can be much more reliable in this situation. All of the global models are in excellent agreement so we can anticipate the consensus to verify generally well. Moreover, the current steering pattern is already setup for a track near the Carolinas, but with a significant curve to the northeast just before landfall. CIMSS 500-850MB Steering Wind Analysis shows that a weak surface ridge near 28摸/68斡 is inducing a south-southeasterly flow along the eastern Bahamas. To the north the upper trough has enhanced the influx of westerlies streaming into the northwest Atlantic from the Great Lakes. All global models (CMC, UKMET, ECMWF, GFS, NOGAPS) indicate that the westerly flow will persist for an additional 72 hours before a mid level ridge over the Rockies propogates eastward in 96-120 hours. The developing tropical cyclone should be in the process of recurving out to sea and away from the East Coast prior to the ridge's arrival. With the exception of 3-4 foot swells along the Carolinas and 4-5 foot swells near the Outerbanks of North Carolina the effects of the cyclone on the East Coast will be limited if the tracks verify.

The tropical wave in the western Caribbean Sea will have to be monitored for potential tropical cyclogensis in the medium range. Currently, land interaction with Honduras and the Yucatan Peninsula and upper level wind shear is putting a damper on development. An upper level low over the northern Yucatan is the main upper shear culprit, but water vapor imagery clearly shows that the feature is backing off to the west. In addition, most global models show an increase in ridging aloft over the southern Gulf of Mexico in 72 hours, which is where the wave will be located by that time. The formation of a Tropical Depression or Tropical Storm is possible in the Bay of Campeche or southwest Gulf of Mexico within approximately 60-84 hours. The steering flow will result in another trajectory similar to that of Hurricane Emily. A cyclonic flow is noted just south of Central America In the low to mid levels. This cyclonic motion will force the wave westward into the BOC/GOM within 2 days. Once in the Gulf, the wave will attempt to move northerly, but the mid level ridge progressing eastward from the Rockies to the East Coast will shun the low pressure area towards northern Mexico or southern Texas in the same manner Emily was guided westward. Initial guidances takes the low into Mexico, but the models are just beginning to pick up on the feature and some minor changes should be expected.

In the western Pacific, Tropical Storm Nalgae (07W) is forecast to remain a tropical storm throughout its lifespan. Nalgae is moving towards the northwest, and a gradual turn to the north-northeast is anticipated within the next 4 days. The latest Joint Typhoon Warning Center track would take Nalgae well to the east of Japan. As the tropical cyclone reaches the 35摸 latitude, it will begin to acquire nontropical characteristics and dissipation will soon follow. Nalgae is not expected to be a major threat to any landmasses.

Advisories on Tropical Depression 07W have also been initiated by the JTWC. In 72 hours, the JTWC is indicating further strengthening to typhoon status along with a curve to the north-northwest in the general direction of Japan. The 12Z ECMWF, NOGAPS, and GFS all take 07W relatively close to Tokyo in approximately 72 hours. If the NOGAPS and GFS solutions turn out to be correct, then 07W will pass east of Tokyo while acquiring nontropical characteristics. The ECMWF, on the other hand, depicts a continued northerly motion into Japan as a subtropical storm. It is still too early to determine the probability of a Japan landfall. Please turn to the Japan Meteorological Agency (JMA) and Joint Typhoon Warning Center (JTWC) for continuous updates.

July 20 2005 - 22:00 UTC

Hurricane Emily made landfall in northeastern Mexico early this morning as a category 3 with winds of 125MPH. The storm is now weakening and slowly moving westward inland, and dissipation should commence in the next few days.

The Atlantic Basin has not returned to total tranquility. A tropical wave located over Hispaniola is inducing moderate convection east of the Turks and Caicos islands. Visible satellite imagery depicts possible mid-level rotation in this convective mass, and the system itself has earned INVEST 90L classification by the NRL Monterey. As far as tropical cyclone development is concerned, the disturbance has a long ways to go. However, conditions are gradually becoming more favorable with time. The upper-level trough over Cuba is driving subsidence into the area via the cyclonic flow, not to mention is keeping shear on the higher side. This feature will be sliding westward over the next several days, and should thus allow the upper-level ridge nearby to become more dominant over the storm. Due to the improvement in conditions, some slow development is possible.

The main inhibitor for a significant tropical cyclone will be the lack of time. 90L is being guided west-northwestward under a surface ridge of high pressure. 12Z global models, which all now pick up on the feature, are in agreement that an oncoming cold front along the seaboard will be sufficient enough to result in a more southerly steering flow and push the high further east. Hence, the system would slowly curve northward over the next 2-3 days. GFS and NOGAPS are the furthest east in their solutions, and keep the storm well offshore the southeast coast altogether. The fact that the GFS shows this, yet the latest tropical models run off the same data have it going into Florida, is rather peculiar. However, all tropical models are suspect at this time since there is nothing resembling a closed surface low. Furthermore, the only tropical model worth taking into account in this case is the BAMM, and so the GFS itself is more reliable. The ECMWF and CMC are slightly further west and have a weak tropical cyclone brushing the Outer Banks of North Carolina in 3-4 days. The UKMET is the furthest west and does not show recurvature until the storm is inland the Florida Peninsula, making it the closest to the tropical runs.

Based on the current model consensus, a track into the Gulf of Mexico does not seem very likely at this point. The problem is since the system is weak and far from a tropical cyclone, there very well may large swings in the consensus track. As it stands now, most likely scenario is no more than a weak tropical storm moving just offshore the southeast United States. It's worth watching and the outlined likelihood is subject to change.

In the West Pacific, Tropical Storm Nalgae is moving northwest in the high-latitudes. Nalgae is expected to remain well east of Japan and max out as a strong tropical storm or weak typhoon. Another well organized disturbance further south has very defined outflow channels and a favorable environment aloft. Development seems likely from this area over the next few days.

IWIC Worldwide Tropical Weather Discussion - July 18 2005 - 21:00 UTC

A few hours ago, TPC aircraft reconnaissance flew into Hurricane Emily for the first time since its center emerged from the Yucatan Peninsula. Recon discovered that Emily weakened much more over land than previously thought. The highest sustained wind found was 75mph, which is barely even Category 1 status. Estimated pressure was 984mb, but recent vortex data messages indicate that the pressure may be beginning to fall once again. The dramatic weakening of the hurricane should not be viewed as an indication that it will be much weaker than forecast at landfall. There is no reason for Emily not to rapidly intensify over the next 24-36 hours. The deep layer ridge aloft has not weakened, and is still located directly over the tropical cyclone. CIMSS Shear Tendency maps reveal that upper level winds are almost nonexistant. Furthermore, the upper level low located over the Bay of Campeche is dropping south and away from the southern semicircle of the storm. Sea surface temperatures are more than conducive for rapid tropical cyclogenesis. The thermocline may be shallow, but Emily's moderate forward speed will likely diminish the effects of upwelling commonly seen during slow moving, intense hurricanes. The SHIPS model ramps Emily up to 80 knots (90mph) just prior to hitting land at 24 hours. However, it is our assumption that the model is being too conservative and that a Category 3 landfall is more likely given the upper conditions, water temperatures, and the hurricane's well developed structure.

There have been some changes in the global model guidance over the last 12 hours. Today's 00Z and 12Z NOGAPS, which has had the best handle on TCs this season, has shifted slightly northward. The NGP shows the center passing just south of the border in 24-36 hours. The 12Z UKMET, ECMWF, and GFS also show landfall just south of Brownsville. The 00Z Canadian shifted as far north as Corpus Christi, but as of the 12Z run it is closer the border and more in line with the consensus. Meanwhile, the 12Z GFDL is the southern outlier with a landfall near Ciudad Victoria, Mexico. 300-850MB steering layer analysis reveals that the subtropical ridge has not expanded westward enough to enforce a due west shift over the next 12-18 hours. Therefore, a landfall in the general vicinity of Matamoros, Mexico, within 24-36 hours is forecast. Such a path would place Brownsvile very close to the northern semicircle of the inner core. All Texas residents south of Baffin Bay should not let their guard down. Coastal northeast Mexico should be well prepared for a direct hit by now; the Tropical Prediction Center's forecasts have been very consistent.

Aside from Emily, the tropical Atlantic Basin is seasonably quiet. A large-amplitude tropical wave is approaching the Windward Islands. Convection is being divergently enhanced by a sharp upper-level trough just to the west. This feature, while aiding convection, is resulting in strong shear over the area. Development is not expected anytime soon. Since it is mid July now, the low-level steering flow is straight westward even past 80斡, rather than bending more northwestward as it usually is earlier in this season. Such a flow allowed waves to move further north and develop in the northwest Caribbean or southern Gulf of Mexico earlier this year. A similar case is not expected with the more easterly flow, though the wave will be watched as it moves through the Caribbean Sea.

Several global models are picking up on a broad low-pressure emerging off the coast of Africa over the next few days. The CMC is the most aggressive and shows what seems to be a tropical cyclone moving westward across the Atlantic through the forecast period. The 12Z GFS and ECMWF are less bullish, but still pick up on a large low and show the same general westward movement. The UKMET and NOGAPS only slightly depict the low at all. The model support is somewhat lackluster as far as a bonified tropical system goes, but the presence of a large low in the tropical Atlantic is worth noting nonetheless. With the subtropical jet positioning further north and relatively moist air, conditions are not all that suppressive. Sea surface temperatures, although warmer than average, are still slightly on the cool side in the east Atlantic, so if a low does develop as the models suggest, it may very well be devoid of convection at first. If it makes it west of 40斡, it is then where convection may increase. The chance of development is slim at this time, but it is something we will keep watching in the models.

The disturbed weather offshore western Mexico has gained enough organization to be classified as a tropical cyclone. A ship reported tropical depression force winds on the west side of the center, and since winds are presumably stronger on the east, the system has been upgraded straight to Tropical Storm Eugene by the National Hurricane Center. The convection associated with Eugene is not very healthy, and is lacking near the center. However, Eugene is located underneath a small anticyclone aloft, and thus the outflow regime is fairly organized, particularly in the southern quadrant. There is some easterly low impacting the system, but it is relatively low and not noticeable on satellite imagery. Overall, the storm has a fairly ideal environment to work with over the next 24 to 36 hours. Gradual intensification is likely, and it would not be surprising to see Eugene peak around 55-60 knots. The system is being steered west-northwest by a ridge of high pressure, and this general motion should continue over the next few days. This path will keep Eugene away from Mexico or any other landmasses.

July 17 2005 - 20:00 UTC

Brief discussion today...Emily is not a breeze, but the setup is...

Emily is not the most symmetrical major hurricane, but it is a major hurricane nonetheless. Infrared satellite imagery shows a limited outflow pattern across the storm and a ragged core convection regime. The eye itself is ragged too and only faintly noticeable. Some additional slight weakening is possible later today, but overall it should fluctuate in intensity between 110 and 130 knots during the rest of its time over Caribbean waters. The upper-level shearing environment is modest at best, and should not pose a major problem upon Emily's strength. Weakening, possibly below major hurricane strength, should commence inland the Yucatan Peninsula, but nce Emily enters the Gulf of Mexico, reintensification is probable. There is no reason why Emily should not become a major hurricane in the Gulf of Mexico, but time probably will not allow more than a category 3.

The future track of the hurricane is extremely straightforward. Emily is being guided west-northwestward under deep-layer currents associated with the subtropical ridge. The alignment of this ridge is not expected to alter much over the next several days, and thus a continued motion is likely. One small blip in the flow will be the passage of a trough well to the north of Emily and over the continental United States. This will temporarily thrust the steering flow slightly poleward, and during that time a more northerly component to the track will commence. However, once this surpasses Emily's longitude, the ridging is progged to build back in an even more west-to-east angle. This is the reasoning behind the forecasts for Emily to bend a little more to the west once in the western Gulf of Mexico. Global model guidance remains in tight agreement on this general track. A first landfall near or just south of Cozumel along the Yucatan Peninsula is expected in 12-24 hours. The second landfall is still forecast between Matamoros and Tampico, Mexico. All in all, we have no disagreements with the National Hurricane Center's thoughts on this storm, track or intensity.

Other than Emily, the Atlantic is quiet. With no other Atlantic storms on the horizon, we may finally be heading for a lull once Emily is finished. In the East Pacific, an area of disturbed weather is slowly consolidating southwest of Mexico. Conditions favor slow development, and several global models indicate tropical cyclone formation in this area. Further west, Super Typhoon Haitang is still threatening Tawain. Refer to the Joint Typhoon Warning Center and our information on the front page for more details on this typhoon.

July 17 2005 - 02:00 UTC

The biggest problem with last night's ideas was that the upper air environment was not conducive enough to support anything more than limited intensification. Well, rapid intensification would be a better phrase to describe today's consistent pressure drops. The intensity forecast was a bust no doubt, but part of the problem was that Emily was stronger than indicated by the official 5PM EDT advisory yesterday afternoon. When aircraft reconnaissance investigated the eye later that evening they discovered that the pressure had fallen 18MB since the last mission.

A continued west-northwest motion is expected through the short term. Anxiety concerning a Grand Cayman directly hit increased this afternoon when a northerly wobble occured, but Emily has since taken a wobble back towards the west. Emily should make landfall along the Yucatan Peninsula as a Category 4 or Category 5. Upper level winds are more favorable than initially forecast. The deep layer ridge aloft has been moving westward in tandem with the hurricane, and there are no signs of the upper pattern shifting. The only other notewory feature that is nearby in the upper levels is an upper low over the southeast Gulf of Mexico, which is enhancing the northerly jet over the northern semicircircle. At the surface, there is more oceanic heat content in the northwest Caribbean than in any other region of the Atlantic Basin. These conditions are prime for Emily to sustain itself as a Category 4 or strengthen slightly/temporarily into a Category 5. Eyewall Replacement Cycles will be responsible for slight fluctuations in intensity up until landfall. Landfall between Tulum and Cancun (this includes Cozumel) is most likely within 24-36 hours. Once back over the Gulf of Mexico, conditions will be favorable for reintensification. In light of the recent intensification of Emily and its potential track along the northern Yucatan, Emily may enter the Gulf as a Category 2 or possibly even a Category 3 storm. Emily could make it back up to Category 4 status by secondary landfall. Secondary landfall is still expected between Matamoros and Tampico, Mexico. As stated yesterday evening, the coastal area just north of Tampico may be at highest risk.

July 16 2005 - 02:00

No arguments with the NHC forecast...

Emily has re-intensified into Category 3 major hurricane status this evening. the temporary weakening during the afternoon hours was a result of an eyewall replacement cycle (ERC). Furthermore, an outflow boundary noted on satellite imagery emerged from the western semicircle of the cyclone during the ERC. Research has shown that re-intensification often occurs in intense hurricanes once ERCs have been completed and well after an outflow boundary has stabalized the atmosphere; Emily is another example. The main question regarding initial intensity forecasts was how fast the mid to upper trough over the central/western Caribbean would lift out. Apparently, the trough has had little to no effect on the gradual intensification process. In addition, CIMSS Shear Tendency shows that upper level winds are steadily weakening over Emily's projected path. Slow intensification is forecast up until landfall over the Yucatan. Upper winds may not be conducive enough to support a Category 4, however.

The subtropical ridge to the north of Hurricane Emily is extended from just north of Puerto Rico, westward well into the Gulf of Mexico. Nearly all 12Z and 18Z model guidance suggests a continued west-northwest motion through the period. The stretch between Majahual and Tulum appears to be the most likely landfall target along the eastern coast of the Yucatan Peninsula. Landfall will likely occur in 60-72 hours, but conditions could begin to deteriote 6-12 hours prior to that period.

Emily could easily weaken to Category 1 status upon entering the Gulf of Mexico. Once clear of the Yucatan, some strengthening is forecast due to favorable sea surface temperatures and weak winds aloft over the GOM. The subtropical ridge should still be in place, and the west-northwest motion should continue. We do not anticipate the ridge to weaken to the point that would support a more northerly track towards the Texas coast. Secondary landfall between Matamoros and Tampico, Mexico, as a solid Category 2 is forecast. A more southerly track by Days 4-5 is the main difference between the thoughts presented here and those put out by the National Hurricane Center. Please take note that southern Texas is NOT in the clear.

July 15 2005 - 23:00 UTC

Emily has rapidly intensified over the past 24 hours and is now the second major hurricane of 2005 Atlantic season. The organizational structure is healthy but the storm itself is very small. A tiny, pinhole eye is evident in satellite imagery surrounded by a thin cold cloud-top eyewall. Outflow is excellent in all quadrants except to the south, where it is being slightly restricted by South American terrain. The upper-level trough to the northwest should remain a far enough distance to not significantly impede on Emily's strength. In fact, it is actually helping to enhance Emily's left outflow channel by pumping the upper-level ridge to the east. Given the expected continuation of the generally favorable environment, further intensification into a Category Four is likely. Due to Emily's small size, it is more susceptible to robust swings in strength either way. Since conditions will be more favorable than not, at least another period of rapid deepening is easily possible.

The storm is moving towards the west or west-northwest under the easterly flow of the subtropical ridge to the north. The ridge is locked in such an angle where this general motion should continue over the next four days. Global models unambiguously take the storm into or just a scatch north of the Yucatan Peninsula, a reasonable assessment given the outline steering flow. Once Emily arrives in the southern Gulf of Mexico after Day Four, slight diversity arises among the model guidance. The 18Z GFS displays a huge jump north from earlier runs and now takes the storm into central Texas mid next week. The 12Z UKMET is a little further south but still agrees on a Texas landfall. Today's ECMWF and NOGAPS, on the other hand, remain further south and show a hit south of Tampico. The CMC is completely disregarded because it unreasonably loses the system before it would arrive into the Gulf of Mexico.

A Gulf landfall in Mexico remains the most likely solution at this time. Full trust in the 18Z GFS cannot be given since it is a huge jump and may easily be a fluke run. Furthermore, the UKMET has had a large right bias with Emily since it first formed, not to mention a similar issue with Dennis. The NOGAPS has had a great track record this year, and it has been accurately consistent on a more southward movement with Emily so far. We favor the NOGAPS and ECMWF combination over UKMET and one run of the GFS. However, residents along the Texas coast, particularly south of Corpus Christi, should closely follow this storm as a landfall that far north has certainly not been ruled out.

INVEST 99L, the tropical wave and associated low pressure near 40斡, has become slightly better organized today. The upper-level environment is not very conducive, with moderate southwesterly shear having a noticeable impact on the convective pattern. Thus it is no surprise there are very little signs of an outflow regime. However, the system is moving into areas of higher oceanic heat content, and the shearing may subside slightly as the trough bends more to the north. Global models are not as enthused as they were a couple days ago, and the ones that pick up on it such as the UKMET and GFS curve it out to sea in the forecast period. Some slow development is not entirely out of the question. That said, a significant tropical cyclone is unlikely given the conditions.

July 14 2005 - 03:00 UTC

Emily isn't a 2004 Earl repeat afterall...shouldn't be much of a surprise these days...

TPC Aircraft Reconnaissance has found sustained surface winds of 65 knots, which warrants the upgrade to Category One Hurricane status. Furthermore, Emily's satellite signature has improved tremendously over the last 6-12 hours. Emily has provided another example of how we should not deviate from our initial forecasts; the call for a minimal hurricane landfall in the Lesser Antilles. It should be noted that moderate intensification was still called for as long as its structure remained intact during the overnight houts. The recent intensification could have some implications on the entire forecast.

The 990-999MB steering layer is slightly weaker, which will result in a potentially slower forward motion over the next 24-36 hours. Emily also appears to be moving just north of due west, quite a contrast from west-southwest yesterday evening. But In the general scheme of things the steering layer is not expected to change significantly over the next few days. The model consensus is still calling for increased ridging to the north with mid level easterly winds flowing into the Yucatan Peninsula. A Yucatan landfall is still by far the most likely scenario. The only guidance changes from yesterday is that the 18Z GFDL takes the center just north or over the northern coast of the Yucatan, and that the UKMET is more northerly towards Louisiana by Day 6. The UKMET solution still does not appear credible. The consistent NOGAPS and GFS models still suggest a just north of due west motion straight into the peninsula. The next 24 hours will be highly critical. If the models overestimated/underestimated the ridging over the Caribbean it will likely show in tomorrow's model solutions. A track into the Yucatan Channel or western Cuba is not forecast, but if a more northerly motion transpires overnight, then it will have to be looked into a little more.

The intensity forecast is also highly uncertain. An upper level trough is persisting over much of the central and western Caribbean Sea. However, nearly all global models indicate that the deep layer ridge over Emily will continue to move westward, and the trough will split. This is also reflected in the 18Z GFDL and SHIPS intensity guidance. In light of the moderate to rapid deepening of the tropical cyclone the potential for further strengthening is increasing. Emily has had no trouble with South America, and the growing northerly component will only give it more water to deal with over time. Emily has the potential to become a major hurricane within 48 hours. All residents in the southern Lesser Antilles, Netherlands Antilles, Jamaica, Central America, and western Cuba should be keeping a close watch on this intensifying and potentially deadly hurricane.

July 12 2005 - 23:00 UTC

Tropical Storm Emily is bordering tropical wave status tonight. Satellite imagery depicts a fairly well-organized mid-level circulation and an associated outflow regime. However, the surface circulation is not very strong, if it even exists anymore. Although moderate convection has refired close to the center, north-south oriented rippling is now noticed, with the storm on the back-tail end. The rippling pattern is one seen with tropical waves, and this plus a less defined low-level circulation raise the question if we even have a tropical cyclone anymore.

For the purpose of this discussion, we will assume Emily still has a small surface center, though it would not be surprising to see aircraft reconnaissance verify the lack of one tomorrow. Regardless of the exact nature, conditions are not too favorable in the immediate-term. A wide upper-level trough north of the Caribbean Sea is digging a bit more than earlier model runs had progged. This feature is inducing strong shear just north of Emily and is evidently having slight negative affect on the poleward outflow. This trough should remain quasi-stationary over the next few days, and the shearing will not abate until Emily reaches the central Caribbean Sea.

Another hindering factor is the presence of the Saharan Air Layer. This Saharan dust dries up the mid and upper-level troposphere, as can be seen in water-vapor imagery immediately ahead of Emily. Furthermore, the fact that most of the convection is displaced to the west of the circulation suggests an easterly jet, another feature commonly associated with the Saharan Air Layer. Unlike the shear, this has been influencing the system since it was first classified as a depression, and is the main reason why intensification has been slow to occur in the first place. The air's stability may be further enhanced by the common summer heat lows in South America, a region Emily is moving near.

With an already diminishing tropical cyclone-esque satellite presentation, trough-induced shear, easterly wind flow, and stable air, Emily is going to be extremely lucky to make it through the next 36 hours as a classified system. Opening back to a tropical wave, if it has not already occurred, is a possible solution by tomorrow. Whether Emily survives as a tropical cyclone or not, conditions look to be more conducive once it reaches the central Caribbean Sea. Shear from the trough and the influence of the Saharan Air Layer will be reduced by then, and the oceanic heat content is extremely warm. What we have are two scenarios, not all that different, depending on what happens with the status in the near future. If Emily becomes a tropical wave, regeneration back to a tropical storm would certainly be possible in the Caribbean Sea, though a hurricane may be more difficult to achieve since the storm would literally be starting over again. If Emily survives the ongoing obstacles, quick intensification into at least a minimal hurricane seems likely once it is past 75斡. A major hurricane at this time does not appear very likely either way.

The future track of Emily is straightforward. The storm is being guided westward at a fast clip under the subtropical ridge. The ridge is progged to hold very strong over the next several days, even in the Caribbean Sea. Model guidance has continued to shift left today as Emily tracks south of earlier solutions. The 18Z GFS, 18Z NOGAPS, and 12Z ECMWF are all in agreement on a general west to west-northwest motion into the Yucatan Peninsula around Day Six. The 12Z UKMET and 12Z CMC are further north, with the UKMET indicating a Texas threat and the CMC showing what would be a Louisiana storm, both by the end of the forecast period. There is not much trust in either of these models after being incorrect outliers for Dennis. Furthermore, they indicate too much of a northerly component in the eastern Caribbean Sea by having it pass over or just to the south of Hispaniola. A track this far north is highly unlikely given how fast to the west the system is moving now and the extent to which the subtropical ridge is holding.

All this said, a continued track to the west is expected over the next three days, bringing Emily through the southernmost Windward Islands within the next 30 hours at either its current strength or a tropical wave. A more west-northwest motion should commence afterwards and continue in its journey through the Caribbean Sea. Emily should thus make landfall in Belize or the eastern Yucatan coastline in five to six days, as a minimal to moderate hurricane, assuming it does not become completely destroyed beforehand. On this path, Emily could emerge into the Bay of Campeche in a week from now. Therefore, in order for it to hit southern Texas, Emily would have to turn at least north-northwest. To strike east of Houston, it would have to turn just slightly more than a full 90� angle. During this time period, all of the global models show persistant ridging along the Gulf coast. The ridge's periphery may be aligned a bit diagonally to allow for a slight northward momentum once in the Gulf of Mexico, but not enough so to bring to the United States. Bottom line for Emily is that it is going to have a hard time staying alive over the next two days, and if it does, we most likely are looking at a minimal to moderate impact for Central America and Mexico.

The 1012MB low pressure and associated tropical wave approaching 30斡 is now being carried over by the NRL Monterey as INVEST 99L. This low just recently earned a 1.0 rating on the SAB dvorak scale, rightfully so given the already evident banding to the south. Convection is sporadic but increasing with time, and there are already hints of a small outflow regime. Conditions appear marginally favorable ahead. Strong shear associated with the subtropical jet is positioned well north of the system and is thus not an inhibitor. The environment is somewhat stable, and there is slight Saharan dry air nearby. However, at the moment it does not appear to be dry enough to completely shunt development, but will rather just keep development on the slow side as it has done with Emily. The environment and improving organization are consistent with many of the global models showing development over the next few days. The only model that does not indicate a tropical cyclone is the NOGAPS, though it also barely even initializes the low itself. That plus the fact that it is an outlier and has a tendency to catch on to eastern Atlantic development too late make it suspicious. The most bullish models are the GFS and CMC, with the ECMWF and UKMET showing a weaker system. A tropical cyclone is more likely than not, but only slow intensification is forseen through the forecast period.

The steering flow is easterly owing to the strong subtropical ridge, and thus a westward track is expected to continue. All of the models show a west to west-northwest motion in the next four days or so, followed by a gradual turn more towards the northwest as it feels a progged weakness in the ridge. However, this is not a sold recurvature case. First off, several model runs of the ECMWF, CMC, and UKMET have actually had the storm missing the weakness connection and being steered back to the left under more ridging by Day Six. The GFS has not yet shown this type of scenario, no surprise since it is notorious for recurving tropical cyclones early on in this area. It is too early to tell how far west any system will track. Given the slight but sure trends in the model runs, it does not appear it will be steered straight poleward once it ecounters the weakness, but we cannot say with 100% certainty that that would lead to a path all the way to the United States east coast.

July 12 2005 - 02:00 UTC

Tropical Depression Five formed soon after yesterday evening's discussion. TD5 has shown continued signs of organization and intensification since the last update. As of 1745 UTC, Satellite Analysis Branch (SAB) Dvorak Estimates were 2.5, which is indicative of the system being a minimal tropical storm. The Tropical Prediction Center decided that an upgrade at 5PM EDT was not yet warranted. Since the latest SAB estimate was released, convection has increased/consolidated, outflow has expanded to some degree in every quadrant, and banding features are becoming ever more present. An upgrade to tropical storm status is highly anticipated later this evening. Upper level winds are are extremely low, and sea surface temperatures and oceanic heat content near the Lesser Antilles support moderate intensification. The latest SHIPS model strengthens TD5 into an 82 knot borderdline Category 1/2 hurricane in 96 hours prior to Hispaniola landfall. A minimal Category 1 hurricane is forecast to slam into the Lesser Antilles in approximately 72 hours.

A strong easterly flow remains present in all steering layers of the atmosphere. The subtropical ridge stretching across the entire Atlantic is expected to strengthen over the next several days, which should act to prevent any shortwave troughs from having a significant steering influence on the tropical cyclone. Global and tropical model guidance is tightly clustered, and forecast confidence is rather high as a result. The NOGAPS as of 18Z, which as noted in the TPC discussion has been the best performer of the season thus far, continues to suggest a more southerly track into the Caribbean and eventually takes the storm between Jamaica and eastern Cuba by Day 6. Furthermore, the GFDL model continues to shift, and it is trending more westerly with time. Initial landfall is forecast between Guadeloupe and St. Vincent and the Grenadines. The northern Leeward Islands are not expected to face a direct hit, but residents in that area are still advised to keep up with the progress of TD5. The remaining models have consolidated more towards Hispaniola over the last 6 hours. However, the models suggesting a more northerly track also appear to have too much of a northerly component over the next 24 hours given the synoptic steering flow. The intensifying hurricane is forecast to threaten the southwest coast of Haiti, Jamaica, and possibly southeast Cuba in approximately 120 hours.

Tropical Depression Five is not the only area worth watching over the next few days. A tropical wave is noted over and just south of the Cape Verde islands in the far eastern Atlantic. Convection is light and sporadic, no low-level circulation is to be found, though there are some hints of broad mid-level turning. The environment ahead of this wave is not as hostile as it might usually be at this time of the year. Strong westerly shear associated with the subtropical jet is concentrated well to the north. The air is somewhat stable, largely owing to the presence of the Saharan Air Layer, but it does not appear sufficient enough to stop organization.

Several global models indicate tropical cyclone development from this wave over the next four days or so. Surprisingly, all are in pretty tight agreement on track, taking any potential storm generally west-northwestward. On Day Six, the GFS, CMC, UKMET, and ECMWF have a tropical cyclone just north or northeast of the Leeward Islands. The only global model that does not show a tropical cyclone from this wave is the NOGAPS. This model has a tendency to be slow to latch onto development in this area, and future runs may very well come into agreement on the other models. Regardless, most models do show an appreciable system moving generally towards the west. Whether it hits the Lesser Antilles or not largely depends on how far north it develops (assuming it does at all) and how slowly it does. A system that takes a longer time to organize will be more subject to faster easterly flow and thus will pose more of a threat than if it develops more rapidly. If this develops, and the model consensus and marginally conducive conditions suggest that may easily be the case, the steering pattern in a week's time does not show any hints of features that would recurve it. In other words, there stands the possibility that we may be faced with yet another tropical system threatening the United States next week.

July 11 2005 - 01:00 UTC

A 1012MB low pressure center has formed along a vigorous tropical wave approaching 11摸, 45斡. This low has become better organized as low level banding features have become more pronounced over the last 24 hours. Sea surface temperatures are 28�-29慢 (82�-84慚), quite favorable, and upper level winds are only 5-10 knots out ahead of the low. Upper level ridging east of the Lesser Antilles is being supported by an upper low northeast Puerto Rico and an upper trough near 20摸, 45斡. Some dry and Saharan air is one potential inhibitor of development over the next 72 hours. Water vapor imagery indicates that the pool of dry air is moving west in tandem with the upper low north of Puerto Rico, however. The Statistical Hurricane Intensity Prediction Scheme (SHIPS) suggests that conditions are favorable for tropical cyclogenesis. The model strengthens the wave into a 70-73 knot (80-85mph) Category One hurricane within 72-96 hours, which is when the system could possibly threaten the Caribbean.

The subtropical ridge is very strong across much of the Atlantic Ocean in all steering layers of the atmosphere. Moderate to strong easterly flow across the entire Mean Development Region is noted in 200MB-850MB steering layears. This general pattern is not expected to change significantly over the next 3-4 days. The synoptic pattern does support the low continuing on a general westerly track into the Lesser Antilles. 12Z and 18Z tropical and global models are in excellent agreement with a west or west-northwest track between Anguilla and The Grenadines sometime Thursday. Residents within this zone should prepare for occasionally heavy rainfall and gusty winds with this system. It is quite possible that the low could be a classified tropical depression or tropical storm by the time it passes through the islands. Hurricane formation is not suggested by any of the other model guidance other than SHIPS within 72 hours, but the low will be monitored closely for signs of any over-and-above intensification.

The potential tropical storm would be in the general vicinity of Hispaniola by Days 6-7. The strength of the subtropical ridge will determine if the system would enter the western Atlantic or remain in the central Caribbean. Medium range global model guidance indicates that any slight weakening of the subtropical ridge over the western Atlantic as a result of Hurricane Dennis will cease by that period. For example, the 12Z ECMWF shows the ridge extending well into the East Coast by Day 7. It is too early too speculate how much of a threat this system could pose to the southeast United States, but early recurvature is unlikely based on the synoptic pattern and confirmation by medium range model guidance.

A few global models are also trying to develop a tropical wave that has exited the coast of Africa within the last 12 hours. This wave is at least one week from posing a threat to any landmasses. A more detailed analysis of this wave will be posted tomorrow as long as the models are continuing to suggest tropical cyclogenesis.

July 09 2005 - 18:00 UTC

After spending a fairly long time over Cuba, Dennis emerged over the southeastern Gulf of Mexico overnight as a weakened category 1. However, since then it has been reorganizing. The eye seems to be reappearing on visible satellite imagery and becoming more defined with every hour. Furthermore, core convection has tightened, and outflow remains prominent. Latest reconnaissance measurements indicate at least 114MPH flight-level winds and a slowly falling pressure now down to 962MB. Given that it generally takes a few hours for the winds to respond to pressure changes, further increase in wind strength is likely later today.

The upper-level environment surrounding Dennis is very favorable. A quasi-stationary shortwave trough over Texas is inducing strong northerly flow across the central Gulf of Mexico to the west of the storm. This in turn is amplifying the anticyclone aloft over Dennis. A second upper-level low is noted in the Bay of Campeche, which is helping to restrict outflow to the southwest of the center. As suggested by a number of the global models, this upper low should become intertwined with the aformentioned trough. As this takes place, and while Dennis continues to gain latitude, the flow will actually improve further for strengthening. A strong poleward outflow channel may even set up on the left side due to the trough's northerly thrust. These types of trough interactions in the past have often led to a period of storm rapid intensification. Such a cycle, which would ultimately result in a strong category 3 or category 4, cannot be ruled out for Dennis.

Just before landfall, conditions may become slightly more hostile. Once Dennis is further north relative to the trough, the alignment may result in possible dry air intrusion. This would intervene in core convective processes and weaken the storm. Additionally, sea surface temperatures right off the northern Gulf coast are somewhat cooler than they are at Dennis's current and recent locations, which will reduce the amount of heat supply the storm has to feed. Therefore, some amount of weakening immediately before landfall remains probable.

The future track of Dennis largely depends on the shape and angle of the subtropical ridge's western periphery, as well as the associated steering flow with that upper-level trough. Right now, the steering currents from these feature largely suggest a continued motion between northwest and north-northwest over the next 48 hours. The global models are now in a coverged agreement on a landfall between Biloxi and Destin, and this target seems reasonable. One interesting thing to note, however, is the most recent CIMSS 300-850MB steering layer map shows the flow has become more westerly near the northern Gulf coast. This is owing to the amplification and slight southerly drift of the shortwave trough over Texas. This steering shift is most noticeable in the 1500 UTC frame, after the morning global models ran. The 17Z GFDL has shifted further west and shows a landfall along the Mississippi coast, though it is not completely sure if it is reflecting these layers or not. Regardless, given this we are still favoring a landfall further west than than Florida, perhaps closer to the Mississippi/Alabama border.

The BOTTOM LINE is basically unchanged from yesterday. Dennis has potential to quickly ramp up to a major hurricane above 120MPH within the next 36 hours. Some amount of weakening can be expected before it hits, though it will likely strike as at least a category 2. Landfall should be in 2 days, anywhere from Biloxi to Destin; as far west as Mississippi is still very possible. All interest along this zone as well as adjacent coastal regions are urged to closely follow the progress of Dennis and take necessary precautions. Listen to the National Hurricane Center, National Weather Service, or local outlets for official information.

Elsewhere, a tropical wave and associated 1013MB low is located near latitude 36斡. Although upper-level shearing is on the low side ahead, the system is shrouded in dry Saharan air. As a result, convection is currently weak and sporadic. However, some global models are trying to develop a weak tropical cyclone from the system over the next few days as it moves westward. When and if convection increases and becomes sustained, a tropical depression may very well form, though strengthening will be slow. Given that it is located under the subtropical ridge and associated low-level easterly flow, a general westward motion towards the Lesser Antilles will commence over the next several days. Something else worth noting is a few models, GFS being the most robust, show more significant development further east from a tropical wave about to exit the coast of Africa. The model outputs and both of these features will be monitored for any signs of organization.

July 08 2005 - 20:00 UTC

Dennis is making landfall in Cienfuegos, Cuba as a powerful category 4 hurricane with winds of 145mph. Earlier this morning, the eye and eyewall were extremely tight and well organized, as would be expected for such a strong storm. However, Dennis is now probably completing an eyewall-replacement cycle, given the rise in pressure and dissapearance of an eye on Infrared imagery. Weakening as a result of this plus tracking inland Cuba will take place over the next 12-18 hours.

Once the storm emerges into the Gulf of Mexico, probably as a category 3 hurricane, restrengthening is very likely. Dennis is currently being ventilated and provided a sufficient outflow pattern by a large anticyclone of high pressure aloft. The precise centering of the anticyclone over the system is slightly to the northeast of the storm's center itself, and thus outflow is a little more restricted on the opposing sector. This slight restriction will change once the system is in the Gulf. A shortwave trough currently over eastern Texas will be drifting to the east over the next day or so. The poleward flow on the right side of this trough will help induce a strong outflow jet along Dennis's left side. The sufficient outflow on the east side of the storm will remain in place too under the continued presence of the anticyclone aloft. All of the global models reflect this favorable upper-level flow and intensify Dennis in the Gulf of Mexico. Based on this data, quick intensification is expected once Cuba is cleared, and a strong category 4 hurricane once in the Gulf of Mexico is a distinct possibility. Some weakening just prior to landfall is possible with cooler water temperatures and possibly a more stable environment right off the northern Gulf Coast. However, Dennis should still come ashore the United States coast as a major hurricane.

The big question is where on the United States coast will Dennis strike? The global models consensus is a bit more converged today. The UKMET, which has been the westernmost outlier in showing a central Louisiana hit for several days now, has shifted further east and now shows a hit along the Mouth of Mississippi in 60-66 hours. The CMC, on the other hand, has been the easternmost outlier in depicting a path straight through the Florida Peninsula. The latest CMC run now takes it near Fort Walton in 54 hours. These models still represent both edges of the consensus, and with all other solutions in between, we now focus on their respective trends since yesterday. The NOGAPS is very close to the UKMET in having a hit around the Mouth of Mississippi in 60 hours, which is a bit of a shift from yesterday's runs which were more aimed towards the Florida Panhandle. The 12Z ECMWF has Dennis moving inland seemingly near Mobile AL prior to 72 hour lead time, which is slightly further east but overall consistent with its previous runs. Finally, the GFS has been fairly persistent for the past four runs or so on bringing the system into Destin, very similar the latest CMC solution. Tropical models that run off GFS data, including the GFDL and BAMD, are understandably similar. CIMSS steering layer maps and water vapor imagery both indicate the western periphery of the subtropical ridge is remaining intact to the north of Dennis, and it is ultimately this feature that will be the deciding factor in where the storm travels over the next few days.

One test for Dennis is to see where along the northern Cuba coast it exits and moves into the Gulf of Mexico. This is still slightly uncertain owing to probable frictional effects with Cuba's rough topography, which will have an influence on short-term storm movement. Depending on how far west the storm emerges will influence where along the Gulf coast it strikes. The region between Grand Isle and Panama City remains the target, but we will not be able to narrow it down until tomorrow morning at the earliest. Given that the overall model consensus is slightly shifted further west compared to yesterday, and the possible westward jolt in movement due to Cuban interaction, eastern Louisiana and Mississippi are becoming more susceptible for landfall than Alabama and the Florida Panhandle.

The bottom line: near-term weakening will take place while passing over Cuba and completing an eyewall cycle, but reintensification in the Gulf of Mexico to formidable category 4 is probable. Some weakening just prior to Gulf coast landfall can be expected as well. Anywhere from Grand Isle to Panama City is most likely to get hit, though we are favoring somewhere on the west side of this swath. The western Florida Keys are likely to experience hurricane conditions, though a direct landfall is not expected.

If you living in Cuba and the Keys and have not evacuated, this is a very dangerous situation. Remain sheltered and stay closely tuned to statements issued by the National Weather Service, National Hurricane Center, or local outlets. All residents along the northern Gulf coast are urged to stay informed on the dangerous storm and begin necessary preparations.

Besides Dennis, another tropical wave and associated mid-level circulation is located near 25 degrees longitude and moving generally westward. Conditions are closer to neutral than anything; altough shear is very low, the air ahead is also very stable and containing moderate amount of Saharan dust. Global models pick up on it and try to develop a seemingly weak tropical cyclone within the next few days. IF one were to develop, it would potentially threaten the Windward Islands in a week from now given the extent of the subtropical ridge immediately to the north. Many models, most notably the ECMWF and GFS, actually show more enthusiasm in developing another tropical cyclone to the east in four-five days from now. They are probably picking up on a wave that has yet to emerge off the coast of Africa. It is not yet certain which of these systems, if any or both, will develop. In any case, the general area of the deep Atlantic will be monitored in addition to dangerous Hurricane Dennis.

July 08 2005 - 02:00 UTC

Major Hurricane Dennis is making landfall along the southeast coast of Cuba with sustained winds of 130mph, just shy of Category 4 status. The only inhibitor of further strengthening is land interaction. Since Dennis is expected to remain on a general west-northwest or northwest heading over the next 36 hours, some modest weakening will occur. Dennis will emerge from western Cuba and enter the southeast Gulf of Mexico as a Category 2 in all likelyhood, but restrengthening will probably take shape just west of the Florida Keys. It is quite obvious that Dennis has traveled a bit more northerly than initially forecast here, and hurricane forecast winds are very likely where the TPC has issued hurricane warnings this afternoon. Once near the central US Gulf Coast, the hurricane may either sustain itself or weaken slightly, as modest southwest winds along the periphery of the subtropical ridge begin to inhibit Dennis' outflow. However, Dennis will likely be a major hurricane at landfall despite the slight increase in shear.

Thus far, Dennis is quickly becoming the most difficult storm to predict this season. NOAA Water Vapor imagery depicts mid to uper level ridging over the Bahamas, southcentral Florida, and eastern Gulf of Mexico. There is a weak trough stretched across the central and western Gulf Coast, to the north and west of the upper ridge. Currently, the aforementioned trough is being deepened slightly as a result of the remnant of Tropical Storm Cindy, which is quickly lifting northeast over the Mid-Atlantic States. The biggest steering question, is how quickly will the ridge build in the wake caused by Cindy over the central Gulf Coast. If the ridge continues to erode, then a more northerly track will transpire and the west coast of Florida would be placed under a higher risk. On the other hand, increased upper level ridging would enhance the probabilties of a central Gulf Coast landfall. The 12Z NOGAPS (NGP) depicts Dennis making landfall near Mobile in 78 hours. The 18Z GFS is rather similar, with a landfall between Mobile and Pensacola within 78-84 hours. The 18Z GFDL shows an idential track in relation to the GFS, which is somewhat expected since the model is initialized with GFS data. The 12Z ECMWF (European) defines the model consensus, with a Mississippi/Alabama landfall within 72-86 hours. The Canadian (CMC), by far, has been the most easterly model. The model takes the inner core of Dennis almost north-northwest and into the Florida Keys and Naples area. The Canadian is considered the extreme easternmost outlier. This track is highly unlikely when one analyzes the upper level ridging noted on water vapor imagery. Meanwhile, the 12Z UKMET is the westernmost outlier, with a landfall over central Louisiana on Day 4. Finally, I would not bother using the NAM/ETA, FSU MM5, experimental WRF, and the tropical model model suite in regards to tropical cyclone forecasting this season. Each model clearly has a common flaw or bias, which are things we will not get into at this time.

In conclusion, A model consensus is trying to develop between Gulfport, Mississippi, and Pensacola, Florida. The westerly outlier being the UKMET, which is indicative of a central Louisiana landfall. The easterly outlier being the Canadian model, which clearly represents a threat to the entire western half of the Florida peninsula. Based soley on model data, a landfall will occur between central Louisiana and the Florida Panhandle. The Canadian appears so completely oblivious to the ridging that is being disregarded at this time. When taking the synoptic pattern into account, we believe that the areas highest at risk are located between the Mouth of the Mississippi River, Louisiana, and Destin, Florida. The trend to watch for over the next 12-18 hours will be the path of Dennis in relation to the coast of Cuba and its interaction with the ridge over the southeast Gulf of Mexico. If Dennis begins to skirt the southern end of the island, then the more westerly end of our zone would be more likely to be affect. Moreover, a direct central Cuba landfall would suggest a higher Florida Keys threat and a more likely chance of a direct hit on the western Florida Panhandle later on. We will have a much better grasp on Dennis tomorrow afternoon as we begin to see where exactly the center will be moving into the Gulf.

July 07 - 18:00 UTC

Tropical Storm Cindy made landfall in eastern Louisiana last night and is now a weakening tropical depression over land. The remnant system should continue to slide to the northeast over the next few days, bringing heavy rainfall and the threat for tornadoes over parts of the southeast and mid-Atlantic states.

Now that Cindy moving out of the picture, our complete focus can turn to Tropical Storm Dennis.

The storm's satellite presentation is fairly healthy, with deep convective bands wrapping around the center and a very defined anticyclonic outflow regime. Conditions around and ahead Dennis look extremely conducive for further strengthening. A large upper-level anticyclone is centered almost directly over the storm, keeping the storm ventilated. Shear profiles are extremely low in the area, owing in part to this feature. Some moderately stable air is noted to the west of the storm on water vapor imagery, though an image loop shows that it is migrating westward in tandem with the storm and thus should not pose a significant problem. The only factor that may hinder intensification is interaction with the mountainous terrain of Hispaniola. However, Dennis is located far enough south of the large island that any weakening as a result of the high topography would be minute. Therefore, continued strengthening is expected over the next few days while in the Caribbean Sea, and it is likely that Dennis will achieve major category 3 hurricane status before it hits Cuba.

Afterwards, Dennis will enter and spend at least two days in the Gulf of Mexico. During this time, conditions should remain favorable for further strengthening. Global model guidance indicates a shortwave over the Rio Grande Valley, or well to the west of the storm. The upper-level anticyclone currently over Dennis should remain intact and expand in coverage once the storm is in the Gulf of Mexico. These two features will lead to an extremely powerful outflow jet to both the north and south of Dennis after three days, and thus not only a powerful hurricane, but quite feasibly a large one as well. Although last-minute changes in intensity just prior to landfall are uncertain at this point, there is no doubt we are going to be dealing with a major hurricane, category 3 or 4, in the Gulf of Mexico this weekend.

Dennis is currently being steered west-northwestward by a ridge of high pressure to the north. In a general sense, the overall picture is very clear. The ridge's western periphery will be slightly punctured from Cindy, allowing Dennis to turn more towards the northwest sometime in the forecast period until an eventual landfall somewhere along the United States Gulf coast. The precise timing and location of Dennis's movement is where the models are diverged. The 12Z GFS and ECMWF are very similar in taking the storm just north of Jamaica, through western Cuba, and then into central Louisiana on Day Five. The 12Z UKMET is close to that solution, though slightly further east with a landfall closer to New Orleans. The most recent GFDL shows a Mobile Bay hit. The latest NOGAPS is a bit further east, and has Dennis making landfall along the western Florida Panhandle by Day Five. Finally, the 12Z CMC is the outlier, and has the storm crossing eastern Cuba and right through the Florida Peninsula within three days.

What can be deduced from these model runs? Aside from the general picture already mentioned, not much. Rather, it is the model trends that are screaming very important clues as to exactly where along the Gulf coast this will land. The GFS has been slowly trending further west, as have the GFDL and tropical models, though their echoing is to be expected since they are run off GFS information. Recall just a few days ago the GFS had the storm passing over or to the east of Hispaniola. This model's rightward bias was very apparent in the deep Atlantic storms last year. The ECMWF and UKMET too have been trending westward with every run; like the GFS, they were not too long ago depicting a storm veering into the Bahamas or through the Florida peninsula. The NOGAPS has been showing an eastern Gulf of Mexico entrance for several runs now, and we have overall not yet seen any trends or major shifts. The 00Z CMC did show Dennis making landfall along the Alabama coast like the recent NOGAPS, but runs prior were much further east.

The model consensus as a whole has been trending westward. In fact, Dennis has already been moving slightly further south than what many models were just recently showing. The only model that now has it moving into Florida is the CMC. We do not buy this scenario not only because it is alone, but it does not make sense. The model has Cindy's remnants carve a large weakness in the ridge, thus allowing Dennis to be steered more northward quicker. This will not happen because what's left of Cindy is too shallow for such significant ridge erosion to occur. Furthermore, for the CMC's solution to materialize, Dennis will have to turn towards the northwest soon so that it misses Jamaica well to the east. This is highly unlikely, if not impossible, given the current strong easterly mid-level steering flow over the area. The NOGAPS's track shows a similar unrealistic northward bias in the short-term as well, and therefore is probably too far east in its progged landfall. The GFS, ECMWF, and UKMET have certainly not been perfect in handling the synoptic environment, but their constant westward trend is meaningful. It will be interesting to see how much longer these models will shift. With the ridge continuing to appear in the runs stronger, the possibility that Dennis just keeps moving west-northwestward up until the final Gulf landfall cannot yet be ruled out. Based on all of this information, a hit between Chorpus Christi and Biloxi is anticipated. It is still a little too soon to confidentially narrow that swath to a point, but anyone along the entire Gulf coast should closely monitor this system.

July 06 2005 - 01:00 UTC

The discussion will have to be brief this evening.

First, Tropical Storm Cindy will be making landfall in lower Jefferson Parish, Plaquemines Parish, and St. Bernard Parisk over the next 6-8 hours. Maximum sustained winds are 70mph. A couple hours ago, there were signs of further intensification, but the convective bursts have since relaxed. Downtown New Orleans can expect a couple rounds of moderate to occassionaly heavy rainfall, but the worst of the wind and rain will pass barely to the south and east. However, the eastern half of Orleans Parish could still face the brunt of the storm. Sustained winds of 50-60mph, with gusts between 70-80mph are likely in this area. A continued north-northeast track will steer the core of Cindy into southern Mississippi/Alabama within 24 hours. Cindy will likely be a minimal tropical storm by the time she passes through Louisiana. The forecast is straightforward. Please listen to your local National Weather Service for more details.

Tropical Storm Dennis is rapidly becoming the main focal point. Again, not much time this evening so only the basic forecast will be discussed. Dennis is forecast to pass just south of Jamaica as a minimal hurricane in approximately 2 days, but the island could still be affected by the most intense northeast quadrant of the hurricane. By Days 3-4, Category 2 hurricane Dennis could possibly pass between the Yucatan and Cuba...in the Yucatan Channel. The northern Yucatan and western tip of Cuba is strongly advised to monitor the progress of Dennis. Based upon our independent analysis, we do not anticipate any sort of direct hit on central/eastern Cuba or the Florida Keys. As a cautionary measure, I would not rule out tropical storm force winds in both areas, however. Now here's the interesting part. Dennis is roaring across the Caribbean at 20mph. Furthermore, nearly all global models have had a northerly bias in recent years. A Florida landfall is NOT expected. Dennis could easily be a threat for the Gulf Coast from Pensacola, WESTWARD. In fact, a northern Mexico landfall cannot be ruled out, and a Texas landfall is certainly possible. It will be difficult to make a precise forecast without a better model consensus....and some indication of model consistency. The bottom line, being this early in the game, a Category 2+ landfall anywhere from northern Mexico through Pensacola is more likely than a Florida peninsula hit.

July 04 2005 - 20:00 UTC

Don't trust models

First, we will discuss Tropical Depression Three. The low level circulation center that made landfall yesterday evening has struggled with land interaction and some southwest shear being caused from a depression in the eastern Pacific. To some extent, this was expected. In last night's discussion, we expected either relocation closer to the mid circulation or for the mid level circulation to simply become the more dominant one. Visible satellite imagery this afternoon suggests that a new surface circulation is forming north of the Yucatan Peninulsa. The center reformation benefits development in two ways; the mlc and llc are more vertically stacked, and the llc is slightly better protected from southwest winds. We still expect a strong tropical storm, and possibly a minimal Category 1 hurricane at landfall. A Category 2 or higher is unlikely now that it seems like the upper trough over the northwest Gulf is not going to budge. Some southwest shear and dry air associated with the trough should limit rapid intensification.

With center relocation to the north, the track has had to be shifted ever so slightly to the east. Furthermore, as stated yesterday any intensification would support a more northerly track. The mid to upper level steering layers feature a more intense southerly flow straight into Louisiana. Texas is not fully out of the question, but a central or western Louisiana landfall appears more likely at this point. If the track shifts any further east than that, then residents of Mississippi and Alabama should anticipate heavy rainfall. This is shaping up to be a heavy rain and isolated flooding threat along much of the central Gulf Coast. Most areas to the west of the center will experience little.

Rapid intensification is possible, but it is not expected to occur. A strong tropical storm or possibly a minimal Category 1 is forecast to hit the central/western Louisiana coast.

It looks like we may have a bigger problem brewing in the eastern Caribbean Sea. The vigorous tropical wave entering the eastern Caribbean is well-defined, and upper level conditions out ahead of the system are very favorable for further intensification. The wave could easily be upgraded to tropical depression status within the next 36 hours. The only factor that could inhibit this system from becoming a hurricane would be too much land interaction with the Greater Antilles.

There is only one word I can use to describe the 12Z model tracks, and that is "bizarre". I could easily be wrong, but the sudden progged shift in general heading towards Hispaniola within 24 hours appears very suspect. The wave is coming into the Caribbean at the lowest latitude possible, it is roaring west at 15-20mph, and the surface ridge, while weakening over the western Atlantic, is still in tact. By Day 3, the 12Z ECMWF shows a potential tropical storm along the northern coast of Hispaniola. The model appears well to far north and way too slow. The end result is a hurricane or stronger making landfall in southeast Florida by Day 6. The 12Z GFS is nearly identical. The 12Z Canadian is slightly more believable. The model takes the cyclone more towards eastern Cuba, and shows a Florida Keys landfall by Day 4, a lot sooner than the Euro. The 12Z UKMET is hardly picking up on the system, but it does indicate a similar track. Meanwhile, out of all of the global models, the 12Z NOGAPS may have the best handle on the system. It is the only model that shows an east Gulf track. The only reason is because a track closer to Jamaica appears much more likely. This is not the first time such a model consensus has busted badly. In fact, this was a common model problem with several tropical systems during the 2004 season.

If the busted model consensus assumption is correct, then a tropical storm or minimal hurricane will likely be skirting the southern coast of Cuba by Days 4-5. If "Dennis" crosses Cuba, it would probably do so near the Isle of Youth. By the end of the medium range, the system could be threatening the west coast of Florida. Please caution that this is not an official forecast, and that changes to the forecast will likely be made withint he next 4-5 days.

July 04 2004 - 00:00

An explosion of convection has developed directly over the surface circulation of Tropical Depression Three within the last two hours. TPC Reconnaissance Aircraft had found 35mph sustained winds earlier this afternoon, and this recent burst may be enough to warrant an upgrade to tropical storm status just prior to landfall over the Yucatan. The bottom line for the Yucatan is that a 35-45mph tropical cyclone will be making landfall within 36 hours. Strong winds will not be a significant risk; heavy rainfall is the primary threat.

The low level circulation center is drifting west-northwest. Once over the Yucatan, a more northerly track may begin. The mid-level circulation, which has been around for several days, is still apparent northeast of the circulation. While the surface circulation has become more intense over the past couple hours, the mid level circulation may still affect the steering of the system. The center is barely passing north of Belize this evening, but a surface trough extends as far north as the northern Yucatan coast. The circulation may easily slide further north along the surface trough, and that would cause for a more interesting situation. If the LLC and MLC become vertically stacked, with upper ridging centered over the entire system, then more development than forecast could occur. Today's 12Z and 18Z model guidance had a very difficult time initializing the tropical cyclone. The model initialization is so bad that the data is not even considered "guidance" for this forecast. A 40-45mph exiting the coast is very possible, and a couple noteworthly systems have developed slightly while over the Yucatan in the past, so it can happen. Once in the Gulf of Mexico, further strengthening should occur. The Decay Statistical Hurricane Intensity Prediction Scheme (DSHP) suggests a 50 knot tropical storm landfall within 72-96 hours, and that is the main reasoning behind the TPC's 4PM intensity forecast. The Caribbean anticylone will move northwest into the Gulf of Mexico in tandem with the depression. Upper winds should remain favorable, especially in the eastern and southern semicircles. The only potential inhibitor is weak upper troughing in the western Gulf. Unfortunately, if the developing cyclone moves more northerly and parallels the trough, then the poleward outflow jet could also be enhanced. Put it this way, if the models were more bullish, the TPC would easily be calling for at least a minimal hurricane by US Gulf Coast landfall. The pattern is ominous, and all residents of the central and western US Gulf Coast are urged to monitor the system closely during the 4th of July Holiday. Rapid development is not forecast, but the main point is that it is becoming a possibility. A strong tropical storm or minimal Category 1 hurricane is most likely at this time, but the forecast may be bumped up tomorrow.

The general area of landfall is fairly obvious at this point, somewhere along the Texas or Louisiana coast. The longer the depression takes to develop, the more westerly it will travel. If the system were to rapidly intensify in the Gulf, then a Louisiana landfall is clearly favored. One will notice that the subtropical high over the Bahamas and southerly flow in the central Gulf along its westerly periphery is much stronger in the mid to upper levels. To sum things up, it is quite possible that coastal Louisiana will face the brunt of this system regardless of how much it intensifies. If the cyclone remains a tropical storm or less, then the southwest shear responsible for limiting development will keep the bulk of moisture and convective activity east of the surface center. On the other hand, a more intense hurricane would be steered by the southerly flow, which means straight into Louisiana. But lets not jump to conclusions, Galveston and Houston is still faced with a serious threat mid-week, and there is still a lot of time to watch the progress of the system.

Unfortunately, the tropical wave moving into the Lesser Antilles will bear just as much or more watching over the next week or so. The realization that a secondary development in the western Caribbean came to light yesterday evening. The wave, which was located near 50斡 at the time, began to show on infrared imagery with several clusters of disorganized convection. At 00Z, the CMC and ECMWF both began to depict tropical cyclogenesis near the Yucatan Peninsula in 144-168hrs. In addition, yesterday's 00Z and 12Z runs of the NOGAPS depicted a tropical depression developing from the same wave, but in the Bahamas rather than the Caribbean. Today, the ECMWF has backed off some (that can be expected this early), but the Canadian has become slightly more bullish on development once in the southern Gulf. Furthermore, the NOGAPS has shifted its track into the southeast Gulf at 144hrs as of 18Z. The upper level environment ahead of this wave is expected to be conducive for tropical cyclone formation. It looks like if the wave remains south of Cuba, then development will be nearly certain. The wave is coming into the Caribbean at a fairly low latitude, which leads to more reasoning as to why there will not be recurvature prior to 80斡, if ever. Tropical development is fairly likely in the NW Caribbean or southern Gulf of Mexico in 5-7 days.

July 03 2005 - 02:00 UTC

The tropical wave located over the western Caribbean Sea is the main area of interest this evening. While convection has persisted an additional 24 hours, there are no signs of a low level surface circulation center. Surface observations also indicate that we are dealing with nothing more than an inverted surface trough at this time. If a surface circulation were to form over the next 36 hours, it would likely spin up north of Honduras and just east of the Yucatan Peninsula. The two inhibitors of development in the short term are the upper low near the Isle of Youth, Cuba, and another upper low over the Yucatan. The two upper level features are making for a decent upper trough to the north and west of the system of interest. To the south of this upper trough, an upper level ridge is trying to develop along the southern half of the wave axis. In fact, a fairly decent outflow channel has developed in the southeast quadrant.

The upper low near Cuba is beginning to move northward and that general movement is expected to continue. Within 1-2 days, the low will no longer be considered a major inhibitor of development. By 72 hours, the upper feature will be inland over the Florida panhandle. Meanwhile, the upper low near the Yucatan will move northwest in tandem with the wave. Within 24-36 hours, the wave will be moving into the Yucatan Peninsula, and into the central Gulf of Mexico in around 48 hours. Some development prior to Yucatan landfall is possible since the upper low near Cuba will be lifting northward and the ridge continues to build. A TPC Reconnaissance Aircraft will investigate the wave to make sure a LLCC has not formed. It is unlikely that the Yucatan would face anything stronger than a 40mph tropical storm. Once in the central Gulf, additional slow development is possible. The Yucatan upper low will move northwest towards the Texas coast over the next 3 days. As a result, some southwest shear will always be present over the tropical low. However, the southwest winds will enhance upper level diffluence in the northern quadrant while the anticylone over the southern half of the system enhances the southeast quadrant. None of the global models develop a tropical cyclone, but it is conceivable given the atmospheric conditions. If a tropical cyclone does form in the central Gulf of Mexico, then it would likely be one-sided, with the bulk of activity remaining near and east of the center. The 18Z GFS, 12Z CMC, and 12Z UKMET do show a 950MB vorticy center moving towards the Louisiana coast. in around 3 days. The NOGAPS and ECMWF should probably be discounted since they do not appear to be picking up the true extent of the energy currently in the western Caribbean Sea. It is possible that even the GFS, CMC, and UKMET could be downplaying development a bit. DSHP has a 50 knot tropical storm progged to hit the gulf Coast by 72-96 hours..

In conclusion, it is too early to determine whether development will or will not occur. Tomorrow's recon will give all forecasters a much better handle on what kind of system we are dealing with. If the hurricane hunters do find a developing low level circulation, then we could easily be talking about a moderate or strong tropical storm for the Gulf Coast early to mid week. The system will not weaken much over the northern Yucatan; it does not have much to lose and it will spend very little time over land. Heavy rainfall should be expected over much of the Gulf Coast to say the least.

A tropical wave in the central Atlantic near 50斡 has flared over the last 6 hours this evening. This convection is primarily shear induced, but the wave axis does have to be monitored. The wave is forecast to travel west-northwest along the southern half of the Greater Antilles once in the Caribbean Sea. By 144 hours, the 18Z NOGAPS takes this wave northward into the Bahamas, where it attempts to develop a weak tropical depression just east of southern Florida. This is the only model that shows such a solution. for instance, the 12Z ECMWF appears to be taking the wave into the eastern Gulf of Mexico by Day 7. The GFS loses the wave by 144 hours near Cuba. Tropical development is not expected, but the NOGAPS scenario will continue to be investigated.

In 120 hours, the 18Z GFS and 12Z UKMET show yet another tropical wave passing over the Lesser Antilles. This wave is currently located near 35斡. Much of its convection is ITCZ related. Tropical development is not forecast, but it will continue to be monitored.

In the eastern Pacific, a tropical depression may be trying to form along 100斡. The broad low's spiral brands will produce occassionally heavy rainfall along the Mexican coast over the next 36-48 hours, but the core of the developing system will likely remain well offshore.

An highly disorganized area of thunderstorm activity is located just east of the Philippines. Yesterday, several global models began to develop a tropical depression or strom just prior to making landfall near Luzon. However, all of these models have backed off on development over the last 12-24 hours. With the overall satellite presention of the system under investigation, it now looks as if tropical development will not occur.

July 01 2005 - 23:30 UTC

The tropical wave being monitored in the eastern Atlantic is now located near 40斡 and is continuing to move westward. Conditions in this area are still too unfavorable for significant short term development. Satellite imagery shows no signs of organization, and there are no signs of a a surface circulation this evening. The majority of model runs apparently developed this wave too fast. There was some speculation that the aggressive models would have too much of a northerly track bias, since a stronger tropical cyclone would be more susceptible to recurvature given the pattern. Since the wave has not intensified over the last few days, the majority of the global models have backed off on development and now show a track through the northern Caribbean. The GFS and ECMWF have been in the most agreement over the last 24 hours; both models show the wave approaching eastern Cuba by 168 hours. Development, if any, would not occur until the wave passes 70斡, and even that seems unlikely.

Convection in the central and western Caribbean Sea remains isolated and disorganized. Upper level winds are light to moderate, but significant development will not occur without consolidation. None of the global models show any tropical development in the Gulf or Caribbean through day 7, but the aforementioned activity is progged to move into the central and west Gulf states at the end of the period. Regardless of TC formation, rain chances will likely be average to above average over portions of Texas and Louisiana during the middle of next week. Tropical development is not expected, but it will be monitored for any signs of organization.

In the eastern Pacific, there are no signs of tropical cyclone formation over th e next few days. As noted in the TPC's outlook, the remnants of Calvin will soon move over cool waters and dissipate. The tropical wave located near 100斡 remains disorganized. Tropical development, if any, would be very slow to occur.

In the western Pacific, 95W INVEST is being monitored for signs of tropical cyclone development. The Joint Typhoon Warning Center has not mentioned the system, but the 12Z runs of the NOGAPS, GFS, and ECMWF are all hinting at TC formation just east of the Phillippines in a few days. It is uncertain if the low will pass just east of the Philippines.

Independent Wx, 2005. All rights reserved.