*******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.*********
...SUNDAY JUNE 23 2024 1:19 AM EDT...
See area of interest #6 section below for an update on the small tropical low currently heading for inland areas of the Carolinas after traversing southeastern coastal Georgia. See area of interest #7 section below for an update on the broad tropical low pressure in the Bay of Campeche and southwestern Gulf of Mexico currently heading toward the Tamaulipas and northern Veracruz region of Mexico.
Noting a band of upper vorticity is forecast to settle across the Gulf of Mexico in the days ahead... more information on that is also in the area of interest #7 section. In the days ahead southern fractures of the current upper trough traversing the US/Canada border region (the same upper trough supporting the current frontal low now heading for the Great Lakes region of North America) and a second similar upper trough that follows behind will re-enforce the Gulf upper vorticity. Then by day 7 the upper vorticity begins to decay from prolonged isolation from high-latitude cold air which would allow tropical upper ridging and outflow over the Caribbean to expand. Models are beginning to converge on a scenario where the tropical wave of low pressure currently at 37.5W longitude takes advantage of the expanding Caribbean upper ridge... resulting in a new area of disturbed weather in the region of Central America in the days ahead. Yet another disturbance in this region would be a concern for rainfall flooding for western Central America and southeastern Mexico as Alberto and area of interest #7 have already saturated the grounds in this region. If current model trends continue... will be upgrading the aforementioned tropical wave to a new area of interest in my next update.
Elsewhere... upper winds in the eastern and central tropical Atlantic (between Africa and the Lesser Antilles) will remain favorable for tropical activity over the next few days due to low shear and outflow provided by the tropical upper ridge axis in the region. However the tropical waves of low pressure passing through the region are not developing... and are not forecast to develop through day 7... due to ongoing outbreaks of dry Saharan air kicked up by the waves when they depart Africa (only exception is this past 1200Z CMC model run which suggests one of the waves evolves into a compact central Atlantic tropical low by day 7... however one model run is not enough of a consensus for this to be a concern at this time).
AREA OF INTEREST #6... The small southeast Georgia tropical low that has been drifting northward inland… but parallel to and near the Georgia coast... continued to be mentioned in the NHC tropical weather outlook for much of Saturday perhaps due to its close proximity to offshore warm Atlantic waters. The small pockets of showers and thunderstorms remain south of center due to ongoing northerly shear… which resulted in locally heavy rain for northeast Florida and southeast Georgia for today. This system will curve north-northeast across the Carolinas over the next 24 hours in the flow ahead of the surface frontal system now working its way into the Great Lakes region of North America from the central US... where it is expected to lose its identity within the low pressure field of the expansive frontal system. The forecast trajectory will keep this system further away from offshore warm Atlantic waters and tropical cyclone formation is no longer possible. It is possible the small pockets of heavy rain from northeast Florida and southeast Georgia pivot into southern South Carolina… with any rainfall across the Carolinas by tomorrow (Sunday) evening associated with the absorbing surface frontal system rather than this area of interest.
This serves as a final update on this area of interest as it continued to be mentioned in the NHC official outlook... and was only recently removed from the NHC outlook at 8 PM EDT
AREA OF INTEREST #7... For the broad tropical low pressure currently covering the southwestern Gulf of Mexico and Bay of Campeche… the NHC issued as a special tropical weather outlook at 5 PM EDT indicating aircraft recon did not spot a well-defined surface center to declare a tropical cyclone. Based on the curvature or recent thunderstorm bands that have rotated into the Mexican province of Tamaulipas my best guess at a center is 23N-96.5W as of this writing… while the NHC TAFB surface analyses and CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) suggest a maximum spin that is further south or southeast. This system has slowed its westward progress as the steering surface ridge to the north has weakened due to the surface frontal system now moving into the Great Lakes region from the central US. However the frontal system will also pass too far north to recurve this area of interest northward... instead the convergent back side of the frontal system’s upper trough will produce a surface ridge that moves across the north-central US and into the Ohio Valley during the forecast period. As a result the forecast track continues slowly to the west thru landfall... with some northward bend in the track after landfall while rounding the southwest side of the Ohio Valley surface ridge. Regarding odds of tropical cyclone formation… the NHC has recently lowered odds to 40% and I have lowered odds to 50% as this system is not producing a thunderstorm core in its central region that would help it acquire a well-defined surface center… and time is running out for this to happen as land interaction with Mexico and unfavorable upper winds spreading in from the northeast (associated with the currently approaching NE Gulf of Mexico upper vorticity band) will begin to hamper development potential in 24+ hours.
Regardless of tropical cyclone formation or not... the main takeaway for this area of interest is that it could produce heavy rainfall with flash flooding potential across Tamaulipas... northern Veracruz... and interior areas of east-central Mexico (provinces just west of the Tamaulipas/northern Veracruz region). Also note thunderstorms and heavy rainfall have recently erupted in the southeast periphery of the circulation… over the Yucatan peninsula of southeastern Mexico. The flooding risk across all of these land areas is enhanced as Tropical Storm Alberto recently saturated the grounds in this region. Gusty winds and coastal surf are also possible for northern Veracruz and Tamaulipas.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Jun 24)... 50% chance of tropical cyclone formation (southern Tamaulipas coast near 23N-98W)
IOH 48 Hr Outlook (0000Z Jun 25)... 0% chance of tropical cyclone formation (northeastern Mexico near 24.5N-99W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT**************************
Formation chance through 48 hours... 40%
Formation chance through 7 days... 40%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Jun 22) CMC Model Run...
**For area of interest #6... through 30 hours while drifting north into the Carolinas becomes absorbed by frontal low moving across Great Lakes region of North America
**For area of interest #7... develops into a tropical depression offshore of the Tamaulipas/Veracruz border at 24 hours... landfall and inland dissipation forecast for 36+ hours
**Tropical wave currently at 37.5W longitude crosses the Atlantic tropical belt and Caribbean… evolves into broad tropical low across Bay of Campeche and northwestern Central America through 168 hours
**Tropical wave enters Atlantic while emerging from Western Africa over next 24 hours… evolves into compact tropical low near 11N-41W at 102 hours... tropical low reaches 12.5N-51W at 168 hours
1200Z (Jun 22) ECMWF Model Run...
**For area of interest #6... Dissipates inland over next 12 hours while drifting north into Georgia/South Carolina border.
**For area of interest #7... tropical low makes landfall at Tamaulipas/Veracruz border at 36 hours without tropical cyclone formation beforehand... with inland dissipation shortly thereafter
1800Z (Jun 22) GFS Model Run...
**For area of interest #6... through 21 hours while drifting north into the Carolinas becomes absorbed by frontal low moving across Great Lakes region of North America
**For area of interest #7... through 18 hours tropical low drifts west-northwest offshore of southern Tamaulipas with possible tropical cyclone formation... from 21 to 36 hours approaches landfall with southern Tamaulipas while weakening... dissipates inland shortly thereafter
**Tropical wave currently at 37.5W longitude crosses the Atlantic tropical belt and Caribbean... evolves into broad tropical low centered over eastern Honduras by 144 hours... broad tropical low continues west-northwest into coastal Belize through 168 hours
1200Z (Jun 22) NAVGEM Model Run...
**For area of interest #6... through 24 hours while drifting north into the Georgia/South Carolina border becomes absorbed by frontal low moving across Great Lakes region of North America
**For area of interest #7... through 42 hours tropical low gradually weakens while making landfall just north of the Tamaulipas/Veracruz border... inland dissipation shortly thereafter
**Tropical wave currently at 37.5W longitude crosses the Atlantic tropical belt and Caribbean... evolves into broad tropical low east of northeastern Nicaragua by 138 hours... through 168 hours continues west-northwest across the north coast of Honduras and toward southern Belize
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