MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #35

*******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.*********

...FRIDAY JULY 11 2025 4:30 PM EDT...

Note the satellite imagery... surface analysis... and upper air analysis in the above chart was completed early today. However since then the overall pattern across the Atlantic basin has not changed.

For the tropical latitudes of the Atlantic basin... tropical development between Africa and the Lesser Antilles continues to be precluded by surges of dry Saharan air. Further west across the Caribbean... where dry Saharan air tends to be in lower concentrations... upper winds are hostile for tropical development as a solidifying band of upper vorticity is producing westerly wind shear. Watching for possible tropical development in the northern Gulf of America in the days ahead in association with a mid-latitude surface trough near the US east coast that retrogrades southwest into the Gulf... see the latter part of the next paragraph for more information.

For the mid-latitudes of the Atlantic basin... the surface trough of low pressure that was over the northwest Bahamas has drifted west into the Florida peninsula... and will soon be merging with a surface trough now advancing toward offshore northwest Atlantic waters from the mid-Atlantic United States. The surface trough is being supported by the eastern divergence zone of a band of upper vorticity currently over the eastern US that has been pinched off from the current eastern Canada upper trough under the force of broad warm core upper ridging to the west being induced by the northward transport of warm air ahead of the current central Canada and central US surface fronts. In the long range the surface trough undergoes a northeast and southwest split:

(1) Regarding the northeast part of the surface trough which will move into offshore northwest Atlantic waters... over next 48 hours tropical development appears less likely as recent model data shows the band of current eastern US cool core upper vorticity may not weaken fast enough within the aforementioned warming environment ahead of the approaching central North American fronts... in which case the lingering remains of the upper vorticity band also slide offshore over the northwestern Atlantic and suppress upper outflow needed for tropical activity. Moreover... after 48 hours the western convergence zone of the upper trough departing eastern Canada produces a surface ridge due south of Nova Scotia and Newfoundland... the west side of the surface ridge will push the surface trough away from the north wall of the warm Gulf stream and into cooler waters.

(2) Regarding the southwest part of the surface trough... which initially hangs around the Carolina coast through 48 hours then retrogrades southwest into the northeastern Gulf of America through 120 hours... the southwest retrogression is to be induced by a surface ridge that builds over the eastern US after 48 hours. The steering eastern US surface ridge then erodes after day 5 (after 120 hours) in the southeast divergence zone of a polar upper vortex that slides southeast into Canada... which causes the surface trough to stall in the northern Gulf followed by a north drift into the US Gulf coast and beyond while attracted toward the surface low pressure field of a surface front to be delivered by the polar upper vortex. Sprawling warm core anticyclonic upper ridging... associated with a warm air mass to the southeast of the Canada polar upper vortex and its surface front... will be in the forecast path of the surface trough. It is possible that some of the slowly decaying eastern US upper vorticity band is pushed south along the path of the surface trough by the anticyclonic upper ridging... however by the time the surface trough is in the northern Gulf any nearby cool core upper vorticity should have collapsed in the sustained warm air regime. This makes for a recipe of possible northern Gulf tropical development of the surface trough thanks to high potential of overhead upper anticyclonic outflow... as such will be on the lookout for possible tropical development in the northern Gulf in the day 4 to 6 window (before the surface trough moves north into the US Gulf coast) even though none of the models are explicitly showing development as of this writing.

...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).

1200Z (Jul 11) CMC Model Run...

**No tropical development shown in the Atlantic basin over the next 168 hours (7 days)

0000Z (Jul 11) ECMWF Model Run...

**No tropical development shown in the Atlantic basin over the next 168 hours (7 days)

1200Z (Jul 11) GFS Model Run...

**No tropical development shown in the Atlantic basin over the next 168 hours (7 days)

1200Z (Jul 11) NAVGEM Model Run...

**No tropical development shown in the Atlantic basin over the next 168 hours (7 days)