WEATHERAmerica Newsletter, Sunday, March 15, 2026; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

 

Early Season Sonoran Heat Ridge Favors Warm West/Central Vs. Lingering Chill Eastern Seaboard

METEOBLUE

TrueWx.Com (4)

ECMWF (4)

College Of DuPage Weather Laboratory (3)

One of the reasons I advise many of you to follow synoptic climatology (storm tracks, anticyclone types and blocking situations, among others...) is that a persistent placement of a 500MB feature can give you insights on how a forecast will turn out not only in the m,medium and longer ranges, but also in seasonal predictions. A case in point is that all of the numerical models build up a strong Sonoran heat ridge, deflating the system only around March 24 or so. Subtropical highs in this position over the Southwest almost always produce record dryness and hot air. If a storm passes along the U.S./Canada border, the warmth will be advected across most of the lower 48 states, with the possible exception of the Pacific Northeast and the Eastern Seaboard. The disturbance may arc across the Great Lakes to the Atlantic shoreline, thus preventing a full surge of higher temperatures from becoming established to the right of the Mississippi River. This is the scenario that seems to fit the upcoming medium range.

With a developing El Nino likely underway, climatology favors a repeated case of a strengthening heat ridge over the southwestern states. After early May (the likely period of MCS formation in the western and central Gulf Coast cities), that ridge should both expand, intensify and marginally regress as we move into and through the JJAS time frame. This is why we need to watch fire and drought/heat threats in a bracket from California to Texas, with some percolation of hot weather into the Deep South and Heartland.