WEATHERAmerica Newsletter, Sunday, December 21, 2025; EXTENDED PERIOD FORECAST

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

Uncertainty And Chaos And The Numerical Models, But Leaning Toward A Stormy Return To The Early December Cold

CIMSS (2)

NOHRSC (2)

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

NOAA/PMEL

NOAA/CPC

IRI/Columbia University

HPRCC/University Of Nebraska (2)

Environment Canada

WeatherBell (8)

I suggest that all of you should review the complete spectrum of weather forecast data related to the extended range (particularly just before New Year's Eve and mid-January). It seems to be a difficult prediction, if only because we have a set temperature and 500MB pattern that seems to go for super-mild conditions nationally, almost always having that one adverse  outlook that wants to enhance the +PNA alignment. It seems a safe bet that the southern tier states, and to some degree the Midwest, will have an extremely warm period through the Christmas holiday period. But there could be a transition to more widespread cold air from Canada around or just after December 28. There is a wide amount of difference in public travel and energy if the New Year is welcomed by very mild readings vs, an icebox that surprises as a shortwave in the polar westerlies dives further south and east than an impulse that only introduces cAk values to New York and New England.

The moderate La Nina episode would favor the cold Canada and Northeast vs. warm across the rest of the lower 48 states. Analogs, including the 2007 warm December vs. cold January have been very sharp because they include the Thaw that concentrates the harshest cold and widespread snow/ice at the start of next month as well as the last week of January acknowledge expansion of snow cover, which is as of now quite incredible and reaching through the northern third of the USA. The Madden-Julian Oscillation leans toward incoherent, with both northern and southern pulses that might allow for an important storm affecting Texas and the Dixie states, moving along the Appalachian Mountains in Piedmont Cyclone fashion. The upper level outlines favor this storm scenario, which if it verifies will flip the nation to a warm West vs. cold Central/East configuration.

A caveat here: the -ENSO will head into a neutral signature as we progress through JFM, which would point toward lower latitude reaches of snow and cold. But an El Nino is not likely to assert its presence until the summer. So if we do see the January Thaw in Weeks 2 to 3, there is a strong risk of Arctic air with a southern/eastern major precipitation and wind event between January 23 and 31.

And Merry/Happy Holidays everyone!

 

Prepared by Meteorologist LARRY COSGROVE on 
Sunday, December 21, 2025 at 12:40 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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