*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.*********
...UPDATE...WEDNESDAY AUGUST 7 2024 8:00 AM EDT...
The surface and upper air charts... which were not previously included in the initial release of this update... are now included.
...TUESDAY AUGUST 6 2024 5:25 PM EDT...

See Tropical Storm Debby section below for more information on its forecast and expected impacts across the eastern United States from Georgia to Maine in the days ahead. See area of interest #16 section below for information on the the tropical wave currently accelerating west across the eastern Caribbean Sea... interests across Nicaragua... Honduras... Belize... the Yucatan peninsula of southeastern Mexico... and the Isthmus of Tehuantepec region of southeastern Mexico should be watching this wave as it potentially encounters upper winds more conducive for its development.
Further east... the recent northeast Atlantic surface frontal cyclone and associated upper trough has helped to push a portion of the regional tropical upper ridge to the south... which in turn has pushed the western part of the African Easterly Jet on the south side of the ridge and the associated surface tropical waves of low pressure further south and away from the dry Saharan air over northern Africa. For now the dry Saharan air outbreak extends into the eastern Atlantic and none of the models develop tropical waves that emerge from Africa in the days ahead... however will become increasingly cautious regarding this region in the days ahead given the shift of the African Easterly Jet to a more south position which may lessen the bursts of dry Saharan air kicked into the Atlantic by the surface waves.
TROPICAL STORM DEBBY... Debby has been lumbering erratically over southern Georgia over the last 24 hours while it was previously trapped between the Atlantic surface ridge to the east and a short-lived surface ridge that was to its north... with the nearby upper trough to the west trying to push the storm east in between the two surface ridges. At first the storm was tracking south of previous forecasts while making a hard-right turn toward the southern Georgia coast... however more recently the track banked more northward with the center now arriving on the southeastern United States coast at the Georgia/South Carolina border. I previously expected the divergence zone of the local upper trough to the west to slow Debby's weakening rate over land... instead Debby has weakened to a minimal tropical storm while losing its core of thunderstorms as water vapor satellite imagery shows the south side of its circulation ingesting dry air... the source of the dry air is likely the western convergence zone of the local upper trough.
Over the next 24 hours Debby's track is expected to bend east into offshore waters as the local upper trough and surface circulation of Debby are pushed by the current shortwave upper trough and surface frontal low that will soon be passing to the north from their current positions over the Ohio Valley region of the United States. I previously anticipated that Debby's thunderstorm latent heat release would amplify warm core upper ridging to the east which would help the local upper trough amplify into an upper vortex... however with Debby's core of thunderstorms gone I now anticipate the upper trough to not close off into a vortex. Therefore the upper-level steering has less of a northward tug in the next 24 hours... however given that Debby is already a bit north of my previous forecast track my 24-hour forecast point ends up being the same as previous with the center offshore but close to the South Carolina coast. I have also lowered my intensity forecast for 24 hours given the low initial strength of the storm and no signs that the storm is re-developing a thunderstorm core as of this writing. Through 48 hours the track changes to a north-northwest angle into inland areas of the Carolinas under the combined influences of the local upper trough to the west... surface ridge that flares up to the north in the western convergence zone of the departing Ohio Valley shortwave upper trough... and attraction toward the ridge weakness associated with a developing Great Lakes frontal low. My updated track during this timeframe is more north and less west as I no longer expect Debby to generate enough thunderstorm latent heat release in time to punch out the local upper trough. Through 72 and 96 hours a re-curvature and acceleration to the north then northeast across inland areas of the mid-Atlantic and northeastern United States is expected as Debby transitions into a remnant frontal low supported by the divergence zone of the US/Canada border region upper trough tied to the Great Lakes frontal low.
The primary impact from Debby in the short-term will be long-lasting bands of heavy rainfall across the Carolinas over the next two and half days... resulting in excess rainfall accumulation and flooding potential... review safety rules for rainfall flooding including not driving vehicles into water-covered roadways to avoid drowning. Gusty winds with isolated damage potential cannot be ruled out over South Carolina and southeastern North Carolina... with surf on the Carolina coast another hazard. Interests in northeastern South Carolina and southeastern North Carolina (coastal and inland) should be preparing for possible tropical storm conditions in the event Debby somehow redevelops a thunderstorm core and re-strengthens more than I indicated in the forecast below... which could result in more widespread wind damage in this region. For the late this week and into the weekend... what is expected to be the remnant frontal low of Debby may re-gain some strength over land while boosted by the divergence zone of the upper trough supporting it... therefore watching for a stretch of possible heavy rainfall... gusty winds... and coastal surf that could develop across the mid-Atlantic and northeastern United States (from Virginia all the way to Maine).
The following are the strongest winds (in mph) at each of the following National Weather Service stations (weather.gov) recorded so far:
**Valdosta (south-central GA)... sustained 30... gust 55... 11:55 AM EDT August 5
**Waycross (southeastern GA)... sustained 24... gust 35... 12:55 PM EDT August 5
**Vidalia (east-central GA)... sustained 23... gust 40... 12:15 AM EDT Today
**Hinesville (east-central GA toward coast)... sustained 21... gust 32... 10:55 PM EDT August 5
**Savannah (northern coastal GA)... sustained 26... gust 35... 12:55 AM EDT Today
**Brunswick (southern coastal GA)... sustained 31... gust 43... 1:35 PM EDT August 5
**Hilton Head (southern tip of SC)... sustained 25... gust 44... 7:50 PM EDT August 5
**Charleston (central SC coast)... sustained 13... gust 24... 10:35 AM EDT Today
**Allendale (inland southern SC)... sustained 18... gust 33... 1:15 AM EDT Today
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Aug 6)... 40 mph maximum sustained wind tropical storm centered on the southeastern United States coast at the Georgia/South Carolina border at 32N-80.9W
IOH 24 Hr Forecast (1800Z Aug 7)... 45 mph maximum sustained wind tropical storm centered just offshore of South Carolina at 32N-79W
IOH 48 Hr Forecast (1800Z Aug 8)... 40 mph maximum sustained wind tropical storm centered over northeastern South Carolina at 33.8N-80W
IOH 72 Hr Forecast (1800Z Aug 9)... 35 mph maximum sustained wind tropical depression transitioning into remnant frontal low over the western North Carolina/Virginia border at 36.2N-80W
IOH 96 Hr Forecast (1800Z Aug 10)... Remnant frontal low centered over eastern New York/Pennsylvania border at 41.8N-75.2W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT************************
Landfall (0000Z Aug 8)... 60 mph maximum sustained wind tropical storm making landfall on the central South Carolina coast at 32.6N-79.3W
5-Day Position (1200Z Aug 11)... 35 mph maximum sustained remnant frontal low centered over Maine at 45N-69W
AREA OF INTEREST #16... The tropical wave of low pressure that recently entered the eastern Caribbean Sea has accelerated westward while also losing thunderstorm activity due to a combination of outflow suppression to the north induced by the nearby western Atlantic upper vortex... and the dominance of the surface inflow toward a developing low pressure gyre of thunderstorms in the southern Caribbean Sea. The tropical wave's acceleration toward the west is due to the tug of the developing southern Caribbean gyre... which itself is developing due to the outflow of a local upper anticyclone that formed in the wake of the weakening upper vorticity that was in the region. This is why models over the last couple of days have shifted possible shorter term development of this area of interest toward the southern Caribbean and Central America... and I have followed suit while now forecasting the surface wave we have been using to track this area of interest to accelerate west-southwest and merge with the gyre over the next 48 hours. Beyond that time... a west-northwest track is shown as a combination of this system initially feeling the surface ridge weakness of Debby... followed by this system rounding the southwest side of the North America surface ridge expected to build behind what will be ex-Debby. The upper wind outlook has shifted in a more favorable direction as Debby is also forecast to be weaker... therefore the disrupting western Atlantic upper vortex spends less time suppressed south by Debby's outflow and toward this area of interest. This gives an opportunity for broad upper anticyclonic flow... featuring favorable low shear and outflow... to stay aligned with this system as the current southern Caribbean anticyclone merges with the ongoing anticycone in the Gulf of Mexico. However I have not raised odds of tropical cyclone formation above 20% due to increased land interaction with the updated forecast track. Even though this system enters the Bay of Campeche waters in 5+ days... I keep odds of development even lower... toward 10%... as their is a possibility that some of the upper vorticity currently over the southeastern US... or some upper vorticity left behind by the upper trough that ultimately supports ex-Debby... gets pushed south into the Gulf of Mexico/Bay of Campeche region... and toward this area of interest... by the ongoing southwestern US upper ridge which could make upper winds less favorable for development via outflow suppression.
Given the latest outlook... interests in Nicaragua... Honduras... Belize... the Yucatan peninsula of southeastern Mexico... and the Isthmus of Tehuantepec region of southeastern Mexico should continue monitoring the progress of this area of interest in the days ahead.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 7)... 0% chance of tropical cyclone formation (central Caribbean Sea near 14N-75W)
IOH 48 Hr Outlook (1800Z Aug 8)... 20% chance of tropical cyclone formation (southern Caribbean east of northern Nicaragua near 13.5N-80.2W)
IOH 72 Hr Outlook (1800Z Aug 9)... 15% chance of tropical cyclone formation (northeastern Nicaragua near 14.5N-84W)
IOH 96 Hr Outlook (1800Z Aug 10)... 20% chance of tropical cyclone formation (just offshore of southern Belize near 16N-88W)
IOH 120 Hr Outlook (1800Z Aug 11)... 10% chance of tropical cyclone formation (southeastern Bay of Campeche coast of Mexico near 19N-92W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT**************************
Formation chance through 48 hours... 10%
Formation chance through 7 days... 30%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Aug 6) CMC Model Run...
**For Tropical Storm Debby... upper trough/vortex over SE US and Debby shift east in next 24 hours toward waters just offshore of southern South Carolina through 24 hours while tugged by passing shortwave upper trough to the north... subsequently the tropical storm whirls northwestward into northwestern South Carolina through 48 hours... turns north across western North Carolina and transitions into a remnant frontal low over central Virginia at 72 hours... remnant frontal low continues north-northeast into southwestern Quebec through northeastern New York through 90 hours... while turning east into tail end of surface front driven by upper vortex/surface low approaching from NE Canada/Greenland the remnant frontal low loses its identity shortly after 90 hours.
**For area of interest #16... organizes into a broad tropical low just east of southern Nicaragua at 42 hours... subsequently turns northwest across northern Nicaragua and eastern Honduras and into northern Belize through 90 hours and enters the southwestern Gulf of Mexico from the Yucatan as a surface trough by 114 hours... trough makes landfall just south of the Texas/Mexico border at 150 hours which dissipates shortly thereafter
0600Z (Aug 6) ECMWF Model Run...
**0600Z and 1800Z ECMWF run data beyond 90 hours not publicly available... today's prior 0000Z run with data through 168+ hours not available at above-mentioned source... therefore ECMWF information on Debby and AOI #16 below ends at 90 hours
**For Tropical Storm Debby... upper trough/vortex over SE US and Debby shift east in the next 24 hours into waters offshore of Georgia through 30 hours while tugged by passing shortwave upper trough to the north... the tropical storm whirls north-northwest around east side of upper vortex through 54 hours and into the northeastern South Carolina coast and transitions into a remnant frontal cyclone while moving into western North Carolina at 78 hours... remnant frontal low/cyclone moves into northern Virginia through 90 hours.
**For area of interest #16... organizes into a broad tropical low just east of southern Nicaragua at 54 hours... weakens back to a wave over Central America shortly thereafter with no development shown thorugh 90 hours
1200Z (Aug 6) GFS Model Run...
**For Tropical Storm Debby... upper trough/vortex over SE US and Debby shift east in next 24 hours toward waters just offshore of southern South Carolina through 30 hours while tugged by passing shortwave upper trough to the north... tropical storm retrogrades back over land at the Georgia/South Carolina border region by 54 hours while moving toward Great Lakes frontal low... while merging with cold front driven by Great Lakes frontal low Debby turns north across the western Carolinas through 78 hours while transitioning into a remnant frontal low... remnant frontal low slides north-northeast across the remainder of the northeastern US (Virginia to Maine) through 108 hours... remnant frontal low arcs north across Quebec through 147 hours which dissipates shortly thereafter under a lack of divergence beneath regional upper trough associated with the surface front.
**For area of interest #16... briefly organizes into a tropical low east of Nicaragua near 12N-81W at 42 hours with no development shown thereafter
0600Z (Aug 6) NAVGEM Model Run...
**For Tropical Storm Debby... upper vortex over SE US and Debby shift east in next 24 hours toward waters just offshore of southern South Carolina through 24 hours while tugged by passing shortwave upper trough to the north... quickly intensifies into a hurricane while curving north into northeastern South Carolina through 54 hours and weakens into an inland tropical storm over central North Carolina at 72 hours... transitions into a remnant frontal cyclone that slides north-northeast across the remainder of the northeastern US (Virginia to Maine) through 114 hours... frontal cyclone weakens to frontal low while arcing more east across New Brunswick and Newfoundland through 132 hours... through 168 hours subsequently loses identity to upper vortex and frontal cyclone diving southeast from Greenland/NE Canada into the northeast Atlantic.
**For area of interest #16... organizes into a broad tropical low east of northern Nicaragua at 54 hours which then makes landfall over the eastern Nicaragua/Honduras border through 78 hours... subsequently weakens to back to a tropical wave with no development shown thereafter
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