WEATHERAmerica Newsletter, EXTENDED PERIOD FORECAST, Saturday, August 9, 2025

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

Google Deepmind Tropical Cyclone Potential

Atlantic Basin Hurricane Threats And The Ongoing Sonoran Vs. Bermudan Heat Ridge Placement Problem

CIMSS (3)

GRAPES/WMO (Beijing)

TropicalTidbits.Com (Dr. Levi Cowan) (3)

NOAA/PMEL

NOAA/CPC

HPRCC/University Of Nebraska (2)

Environment Canada

TropicalTidbits.Com (Dr. Levi Cowan) (5)

WeatherBELL (4)

A good rule of thumb in tropical cyclone forecasting is to keep predictions for track and intensity of storms to out to ten days, and to use definition in outlooks only after the 8 day mark. Because while some equations may hit the mark with certain storms from as much as two weeks away (you remember Sandy in 2012, right?), the most accuracy is found in the medium range, if not the near term. Because warm-core systems are so dependent on mesoscale forces (weaknesses, competitive vortices, and sea surface temperature anomalies, etc.), last minute deviations can occur. I make this remark because it seems obvious that an important hurricane will develop from the ITCZ,with an event about 9 days away. But the (if any) landfall spectrum is still too far-flung to make a reasonable outline. Another clue for a potential impact zone is cooler temperature deviations. That could mean central Texas (which worked for the major rainfall target in early July) or New England (about half of the model ensemble runs are near or over Massachusetts). We should know in another 72 hours if any populated area is involved in the August 16-20 time frame.

Perhaps the more vexing issue is the risk for another major heatwave. Coming off a relatively cool first week of August, I get the impression that many are taking a very bearish, "can't happen here" stance. This is troubling because the ominous heat ridge predictions suggest that anyone living east of the Rocky Mountains and south of 50 N Latitude will have multiple high cooling degree days through the end of this month and the first week of September. Many of the schemes have a trans-ridge gap in (you guessed it) Texas, so the Gulf of Mexico moisture source will be open to provide that "humid" aspect to the "Dog Days Of Summer" forecast. There may be other cases of warm-core cyclogenesis that could impact either the Gulf Coast or Atlantic shoreline, and MCC cases of general thunderstorm activity close to the Canadian border. But the predictive odds point toward the heat getting out of control  from the Great Plains through much of Dixie, with occasional intrusions into the Eastern Seaboard. The last phase of the monsoon should suppress heat in the Desert/Intermountain Regions and the West Coast.

Prepared by Meteorologist LARRY COSGROVE on 
Saturday, August 9, 2025 at 11:40 P.M. CT

Disclaimer: 
The previous statements are my opinions only, and should not be construed as definitive fact. Links provided on this newsletter are not affiliated with WEATHERAmerica and the publisher is not responsible for content posted or associated with those sites.

Copyright 2025 by Larry Cosgrove

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