WEATHERAmerica Newsletter, EXTENDED PERIOD FORECAST, Saturday, August 23, 2025

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

Summer Is Far From Over, And Hurricane Season Is Not Done. Got It?

CIMSS (3)

GRAPES/WMO Beijing

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

NOAA/PMEL

NOAA/CPC

Columbia University/IRI

HPRCC/University Of Nebraska (2)

Environment Canada

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

WeatherBell (4)

NOAA/PSL (2)

NOAA/CPC

One cold front does not mean the heat is gone for good. And the fact that the only major hurricane so far stayed offshore does not mean that the tropical cyclone season is over.

The strengthening La Nina episode is one clue why it is inadvisable to "cancel summer" . Another thing I look at is the network of heat ridges, which looks quite strong and in position to deliver hot air to storms deepening in the mid/high latitudes. The ITCZ in Africa, which has had some of its waves erased by intrusions of dry/hot/dusty air from the Sahara Desert, has produced two viable systems in August and likely will provide two more before Labor Day. A key issue is that we are entering the fragmentation phase for subtropical highs, which will enable some of the disturbances to avoid the cTw realm while also enabling recurvature that could a) take a circulation over very warm water and b) allow for recurvature and interaction with cold-core weaknesses. The latter scenario is what the ECMWF panels are suggesting as we move into September, and might involve a landfall on the Gulf Coast and a track into the Ohio Valley. This set-up is not to be taken lightly, as climatology in a growing (likely moderate range) -ENSO environment and all of the numerical model and analog predictions are illustratiing next month.

Monsoonal moisture that is cooling the West in the remaining days of August will allow for the Sonoran heat ridge to rebuild, which I suspect will translate to a hot West + Canada vs. changeable Central/East alignment after the medium range cool intrusion breaks up. There are sound arguments for heat events in California and the Desert Regions into the lower High Plains, as well as the Northeast. But the storm threat is the looming issue here, as the analog presentation practically screams for a Texas to western New York path. The marginal cool patch shown by the analogs and CanSIPS makes great sense when you place it in the vicinity of the trough>weakness at 500MB that the ECMWF series keeps showing.

Now I wonder if we can keep that trough over the Great Lakes and Mississippi Valley for the coming winter?

 

Prepared by Meteorologist LARRY COSGROVE on 
Saturday, August 23, 2025 at 10:50 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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