WEATHERAmerica Newsletter; Sunday, May 10, 2026; EXTENDED PERIOD FORECAST

[Larry Cosgrove]

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

 

A Cool Canada Vs. Warm/Hot USA Solution?

CIMSS (2)

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

NOAA/PMEL

NOAA/CPC

ECMWF

HPRCC/University Of Nebraska (2)

Environment Canada

WeatherBELL (9)

It would appear that the various numerical models are not seeing the impacts of the El Nino episode now taking shape over the equatorial Pacific Basin.

If you review the various longer term forecast schemes and ensemble platforms, there is still a great deal of chaos with respect to development and placement of heat ridges. Although now weak, I expect a well-organized high-end moderate intensity at the 3.4 benchmark by August 1. On the argument that a stronger +ENSO signature is now likely, then heat ridges should be targeting both the West and the eastern third of the lower 48 states, with a gap or weakness between the two along and over the Mississippi Valley and Great Lakes. ButI am still seeing cold lows with the subtropical jet stream swing through California into Texas, this despite the fact that a) the Madden-Julian Oscillation has shifted to the eastern Indian Ocean and b) a new southern branch is growing below Hawaii with an eventual aim at the Gulf of Alaska. The GFS and CFS series, while not perfect, are the best fit for climatology and more extensive heat for late May and much of June. Thunderstorm impacts seem to be shifting into the Midwest and Great Lakes, which is where I would expect as we move out of Spring.

The NAEFS projection has a more likely placement with a cool Canada vs. warm/hot lower 48 states in Week 2, which I believe will remain if not expand during the month of June. Two things to keep your eye on for possible heatwaves: Ignore climatic indices (which are all the rage now in the weather community) and focus on 500MB structures. If heights are at 588dcm or higher, then that area and its immediate west and north will have extreme surface heating, especially when a core is well-defined (closed circulation present). Look also at water temperatures in the Pacific and Atlantic Basins, which if excessively warm will be supportive of intense Sonoran and Bermudan heat ridges. The gap between the two subtropical highs represents possible paths for disturbances (mesoscale or synoptic, tropical or baroclinic). A key element in temperature prediction, after all, is where rain is present, heat may be diminished. Dryness equates to potential heat, a lesson learned in such major torched summers such as 2011, 2012, 2016 and 2023. I think that heat chances will diminish over the eastern states after July 4, while the West and Central theaters (including Texas) will be hot from late June through the middle of September.

 

Prepared by Meteorologist LARRY COSGROVE on 
Sunday, May 10, 2026 at 2:10 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 2026 by Larry Cosgrove

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