MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #46

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

...SUNDAY JULY 27 2025 4:50 PM EDT...

For the mid-latitudes of the Atlantic basin... the potential for another northern Gulf of America disturbance appears to have diminished. Recently the western convergence zone of a shortwave upper trough passing through the Great Lakes and eastern Canada has increased surface ridging over the lakes... pushing the tail of the surface warm front originally generated by the divergence zone of the shortwave south into a surface trough that was over North Carolina and Virginia. While the surface front/ trough is forecast to turn southwest under the force of the current US Gulf coast surface ridge... followed by a sprawling surface ridge to descend from the US/Canada border while induced by the back convergence zone of the current western Canada upper trough when that trough later shifts southeast... the models have converged on the surface front/ trough tracking over the southeastern United States through day 4 rather than into the northern Gulf.

For the tropical latitudes of the Atlantic basin:

(1) Upper winds in the eastern tropical Atlantic are returning to a mode more conducive for thunderstorm activity while a wave of suppressing upper vorticity is retreating northwest and away while gravitating toward the upper trough west-southwest of the Azores and additional upper trough that has entered the northwest Atlantic from eastern Canada this weekend. However tropical development between the Lesser Antilles and Africa continues to be suppressed by surges of dry Saharan air... and the models are not in agreement in showing tropical development in this region in the days ahead.

(2) Further west in the Caribbean Sea where dry Saharan air concentrations tend to be lower... upper vorticity suppressing thunderstorm activity has arrived from the northeast while pushed by the ongoing southeastern US upper ridge. This upper vorticity has pushed the upper anticyclone that was over the Caribbean westward into Central America and southeastern Mexico... and the CIMSS 850 mb vorticity product shows the northern Honduras mid-level low pressure spin produced by the outflow of the upper anticyclone has also migrated into southeastern Mexico (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). Over the next 4 days the suppressing cool core Caribbean upper vorticity is forecast to weaken and break up due to prolonged isolation from high-latitude cold air... which will return upper winds to a mode favoring thunderstorm activity. However by day 7 upper winds in the Caribbean switch back to a suppressive mode as the current shortwave upper trough currently moving into the north-central US is shown to eventually revolve south around the east side of the ongoing southeastern US upper ridge and toward the Caribbean... translating to another round of suppressing upper vorticity in the region. The models do not show agreement on any Caribbean tropical development in the days ahead.

...COMPUTER MODEL SUMMARY...

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

1200Z (Jul 26) CMC Model Run...

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

1200Z (Jul 27) CMC Model Run...

**Through 96 hours the tropical wave currently at 35W longitude becomes a tropical low near 11N-41.5W... tropical low continues west-northwest and reaches position just north of the Virgin Islands by 168 hours

1200Z (Jul 26) ECMWF Model Run...

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

0000Z (Jul 27) ECWMF Model Run...

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

0000Z (Jul 27) GFS Model Run...

**Current SW/NE tilted western Canada upper trough reaches eastern Canada through 135 hours with the surface front produced by its southeastern divergence zone draped across the northwestern Atlantic by that time... rapid tropical cyclone formation along the front shown near 35.5N-70W at 150 hours... the tropical cyclone is able to intensify through 168 hours as it moves fast enough to the east-northeast to take advantage of the divergence ahead of the upper trough and mitigate the effect of westerly shear imparted by the upper trough and reaches 36N-64.8W

1200Z (Jul 27) GFS Model Run...

**Current SW/NE tilted western Canada upper trough reaches eastern Canada through 126 hours with the surface front produced by its southeastern divergence zone draped across the northwestern Atlantic by that time... rapid tropical cyclone formation along the front shown near 35.5N-70W at 141 hours... the tropical cyclone persists while moving east-northeast at a sufficient speed to mitigate the effect of westerly shear imparted by the upper trough and reaches 36.5N-58.5W by 168 hours

**Additional tropical cyclone develops along decaying northwestern Atlantic front and near 33N-71.5W at 153 hours... the tropical cyclone drifts east to 33N-69W through 168 hours

0000Z (Jul 27) NAVGEM Model Run...

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

1200Z (Jul 27) NAVGEM Model Run...

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