WEATHERAmerica Newsletter, Saturday, March 9, 2024; EXTENDED PERIOD FORECAST

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

Transition From El Nino To La Nina Has Begun; Some Cold Intrusions, Likely Not Long-Lasting

CIMSS (2)

NOHRSC (2)

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

NOAA/PMEL

NOAA/CPC

ECMWF

HPRCC/University Of Nebraska (2)

Environment Canada

ECMWF (4)

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

Forecasting winter to spring transitions is hard enough. But when you add a fairly steep change from an El Nino to a La Nina, things can get really difficult. Note that the sea surface temperature anomalies in ENSO 1.2 and 3 are already rapidly dropping, which tells us that we should be in a negative neutral anomaly further west in the Pacific Basin by August 1. Since hydrothermal patterns are forecast to concurrently warm greatly in the Atlantic Basin, the incentive for heat ridge formation will soon be evident. The southern branch jet stream will then have to gain in latitude (see the AMJ 2m Temperature Anomaly from ECMWF), taking communities in the south central and Dixie states from normal/cool to hot. The transition could set off a staggering amount of severe thunderstorms, with the "Panhandle Hooker "B" favored track in the near term and medium range going over to the Colorado/Limon and Trinidad A/B during April and May. Before we get there, however, the chance for absolutely miserable weather will exist along the Interstate 10, 20 and 40 corridors.

I note that the European panels want the chill to hang on in the Midwest and Eastern Seaboard longer than the outlooks of the GFS and GGEM members. Blocking signatures tend to fragment more quickly the later you go in March, and there are few cases where an entrenched cold can set up. The exceptions, like 1993, 2015 and 2017 are not in the analog list for this year, however, so I see a progressive 500MB pattern with perhaps two or three transient cPk (not cAk) intrusions. We will have to watch for severe weather potential, as return of both hot/dry air from Mexico and warm/moist values out of the western Atlantic Basin is very likely to appear. The dryness over the High Plains and Corn Belt only adds to the drama, so to speak, as its continued presence may point to a rapid turn to heat ridging as we move closer to summer.

Prepared by Meteorologist LARRY COSGROVE on 
Saturday, March 9, 2022 at 10:30 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 2024 by Larry Cosgrove

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