WEATHERAmerica Newsletter, EXTENDED PERIOD FORECAST, Sunday, July 27, 2025

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

Monsoon (Cool) West Vs. Heat Ridge (Hot) Central, East With A Colder Canada? And What About Tropical Cyclones?

CIMSS (3)

GRAPES/WMO Beijing

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

NOAA/PMEL

NOAA/CPC

HPRCC/University Of Nebraska (2)

Environment Canada

WeatherBELL (4)

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

The percolating ITCZ in equatorial Africa is about to join the various features that influence weather in North America. But other extant systems will have a deeper impact, such as the vast ridge complex covering much of the USA. After a period of weakening in the medium range, the conjoined Sonoran + Bermudan superridge will reemerge. Follow the 588dcm contour at 500MB as the rim of the subtropical high. Seeing that the ECMWF and GGEM series handle monsoonal events far better than the GFS model suites, it is fairly obvious that much, if not all, of the Desert and Intermountain Regions will have cooler profiles with cases of diurnal+orographic convection. The first two weeks of August should be the peak of the season, with even the Central Valley of California losing cooling demand. It should take until the second week of September before ridging and drying returns in strength over the West.

We have seen a shifting weakness in New Mexico and Texas in the first part of this month. If the European version is correct in turning that trans-ridge gap into Louisiana, then Kansas, Oklahoma, and Texas will be in line for extreme heat. The impulse passing through the Lesser Antilles could reach the Gulf of Mexico next weekend or shortly thereafter. Passing through very warm waters and getting into light shear in the weakness, you can make a case for a named storm of some kind impacting TX or LA. And if one of the systems further upstream "catches the wave", so to speak, with the Saharan Air Layer not getting involved, we could see a serious wind and precipitation event in either Week 2 or 3 in the major islands and/or along the U.S. shoreline.

The ENSO 3.4 signature is now a weak La Nina. This episode may attain moderate status briefly into the Fall and Winter before  weakening to neutral levels in the coming Spring. Chances for more and stronger tropical cyclones usually increase when the 3.4 sector reaches -1.0 deg C deviation, which is a reason to approach the forecast with a more bullish approach. My outlook remains for22 named storms, 12 hurricanes and 6 major cyclones before the tropical season ends on November 30.

 

Prepared by Meteorologist LARRY COSGROVE on 
Sunday, July 27, 2025 at 1:55 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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