MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #38

*******Note that forecasts 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 JULY 16 2025 7:30 AM EDT...

Was attempting to publish this update at 6:30 AM this morning which was blocked due to loss of internet at my location. Now back online... and this post is now published.

...WEDNESDAY JULY 16 2025 6:30 AM EDT...

See area of interest #9 section below for an update on the tropical low which has moved across northern Florida after being previously offshore of the southeastern United States... currently monitoring for possible reformation of the tropical low into offshore north-central Gulf of America waters which may give it a last chance to develop before later turning north into the southeastern United States. Elsewhere the remainder of the Atlantic tropics are calm due to surges of dry Saharan air currently blanketing from Africa to the eastern Caribbean where wind shear that would otherwise favor tropical development is currently low. Further west across the remainder of the Caribbean and Bay of Campeche... westerly wind shear is elevated due to westerly flow on the south side of an ongoing upper vorticity band in the region.

AREA OF INTEREST #9... Satellite sequence of tropical low pressure offshore of the southeastern United States making landfall across northern Florida from 1630Z Monday July 14 to 0930Z Wednesday July 16. The central position of the tropical low in each image is marked with an "L" based on NHC TAFB surface analyses and satellite observations... same with the black-dashed line which marks the position of a surface trough that the tropical low has been interacting with:

Continuing to monitor the progress of a surface tropical low pressure that has moved across northern Florida after previously being over waters offshore of the southeastern United States while it was pushed by the surface ridge that was over the eastern Great Lakes:

Recent history over last 36 hours... since my previous update Monday evening the core of the tropical low as it approached northern Florida lost thunderstorms while thunderstorms erupted in a band spanning the Florida peninsula... southeastern Georgia... and the central Carolinas. National Weather Service forecast discussions from the Melbourne and Miami offices in Florida confirmed the thunderstorms across the peninsula were driven by increasing instability caused by daytime heating of the landmass and surface sea breeze winds from the coastline converging over the peninsula (reference the Melbourne forecast discussion from 6:48 PM EDT July 14 and Miami forecast discussion from 7:36 PM EDT July 14 by visiting weather.gov... entering Melbourne or Miami in the search box... and using the forecast discussion archives from each office). The position of the thunderstorm band over Georgia and the Carolinas Monday evening also coincided with a surface trough of low pressure consistently analyzed in NHC TAFB surface analyses at the time... this new surface trough was probably generated by split flow upper divergence between the southwesterlies ahead of the upper trough pivoting northward across eastern Canada at the time and northerlies arcing around the east side of the southeastern United States upper anticyclonic ridge and as with any surface low pressure field provided a focal point for surface convergence of daytime-heat induced thunderstorms. The surface inflow of the impressive Monday evening Florida-to-Carolinas band of thunderstorms appears to have taken away from the surface inflow at the core of the tropical low... which allowed the core thunderstorms and associated latent heat release to dissipate which in turn allowed the cool core inverted upper trough incoming from the northeast to slide over the core of the tropical low and suppress its upper outflow... thus it failed to become a tropical cyclone before landfall with northern Florida. By Tuesday the surface trough that was over Georgia/ the Carolinas appeared to have expanded southward toward the tropical low due to the pressure drops induced by the outflow of the thunderstorms that were from the Florida peninsula... then the surface trough appeared to become pulled southwest into the west side of the tropical low where it became increasingly cyclonically curled and as of this writing is now attached to the southwest side of the tropical low. Also note the surface trough also helped to lift the core of the tropical low onto a northward angle keeping it over the Florida panhandle instead of over northeastern Gulf waters... another way the surface trough has precluded development of the tropical low so far. Note the combo of the cyclonically curled surface trough and tropical low center over the Florida panhandle (which provided a focal point for surface convergence)... and instability produced by daytime land heating... produced a cyclonically curved thunderstorm band across the central and western panhandle... southeastern Alabama... northwestern Georgia... and North Carolina for Tuesday evening. In the overnight through early today the previous daytime-heat thunderstorms faded and the surface trough now attached to the southwest side of the tropical low is producing thunderstorms just offshore of the central United States Gulf coast.

Future outlook... the inverted upper trough mentioned in the prior paragraph is now losing identity to the western Atlantic upper vorticity band to the east. The southern nose of the current southeastern US upper anticyclonic ridge sticks out over the north-central Gulf of America in relatively higher upper air pressures between the western Atlantic upper vorticity band and western Gulf of America upper vortex. The anticyclonic outflow of this nose is helping the surface trough produce the aforementioned thunderstorms offshore of the central United States Gulf coast... thus waiting to see if the trough evolves into a new tropical low pressure center as many recent model runs suggest will happen. So far the CIMSS 850 mb vorticity product suggests the old center over the Florida panhandle is still rather dominant (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=)... therefore my 24-hour forecast is a compromise between the models and current observations and has the tropical low only go through a smaller re-positioning which would place it on the US Gulf coast at the Alabama/ Mississippi border where only half the circulation is over water instead of all of it. Therefore my odds of tropical cyclone formation are below the NHC guidance as of this writing. Between 24 and 48 hours the potential for tropical cyclone formation should be over as whatever is left of the surface low pressure field becomes gravitated further north and inland toward the surface front being induced by the southeastern divergence zone of the current Canadian polar upper vortex.

Primary impact to land areas going forward is expected to be periods of heavy rainfall with flash flooding potential across southern Alabama... southern Mississippi... western Florida panhandle... and southeastern Louisiana within the next 48 hours.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (0600Z Jul 17)... 20% chance of tropical cyclone formation (United States Gulf coast in vicinity of the Alabama/ Mississippi border near 30.1N-88.5W)

IOH 48 Hr Outlook (0600Z Jul 18)... 0% chance of tropical cyclone formation (east-central Mississippi near 32.5N-89W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 2 AM 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/).

0000Z (Jul 16) CMC Model Run...

**For area of interest #9... tropical low through 24 hours moves west-northwest from the Florida panhandle to southern Mississippi after which time it dissipates... the surface trough attached to southwest side of the tropical low moves west-northwest for a landfall on the southeast Louisiana coast at 36 hours... evolves into a tropical low while moving into south-central Louisiana at 60 hours... shorty thereafter weakens back to a surface trough that takes an east-west orientation while lifting north... while over NW Arkansas the trough finally loses identity to surface front to the north just after 102 hours

1200Z (Jul 15) ECMWF Model Run...

**For area of interest #9... the original tropical low pressure center over the Florida panhandle dissipates while the surface trough attached to the southwest side of the original center develops into another tropical low as it makes landfall on the southeast Louisiana coast at 48 hours... shorty thereafter weakens back to a surface trough that takes an east-west orientation while lifting north... while over central Arkansas the trough finally loses identity to surface front to the north at 96 hours

0000Z (Jul 16) GFS Model Run...

**For area of interest #9... no development shown

0000Z (Jul 16) NAVGEM Model Run...

**For area of interest #9... over next 12 hours tropical low re-generates to the southwest in waters just offshore of the central Florida panhandle... tropical low makes landfall on the southeast Louisiana coast at 42 hours... while drifting north to inland section of LA/ MS border weakens to a surface trough with east-west orientation by 54 hours... remnant trough dissipates shortly thereafter