WEATHERAmerica Newsletter, Monday, March 17, 2025

[Larry Cosgrove]

Two Concerns: Near-Term Storms And Long-Term Heat/Drought

If you looked carefully at the weather this past weekend, you saw a rather interesting outcome. There was a high wind event that affected Texas and the Great Plains, while the eastern half of the nation had lots of precipitation and reports of tornadoes.

These two occurrences were from different systems, and actually may foretell the course of weather during the next month or two. View of satellite and water vapor imagery show another full-latitude trough and storm along the West Coast. That system is part of a sequence stretching all the way to China. But consider that these impulses are not only strong, but they are in line to get deep tropical moisture and forcing. Evidence the southern branch jet stream coming into Hawaii, which is linked to the otherwise incoherent Madden-Julian Oscillation. The procession of disturbances is mostly lateral (west to east), which implies that while the  Intermountain Region would get copious amounts of moisture, downslope flow into the middle chamber of the continent would be dry. And mostly warm (earning the ImP tag on the air mass after using a dry adiabatic rate in the bowl shaped geography of the Great Plains).

The first low pressure and trough in the series will migrate from California to near Burlington CO on Tuesday night, then rapidly progress to the "Soo Locks" of Ontario and Michigan by Thursday morning. While it is possibole that a thin stripe of heavy snow could impact the western Corn Belt, the strong winds accompanying the tight pressure gradient (978MB at core) are going to raise dust and fire hazards west of the Interstate 35 corridor once more from Texas through Oklahoma and Kansas. Colder air will briefly be drawn south, but just like the past two days quickly be replaced by the warming/drying air mass out of Mexico. It is possible that the low center may redevelop off of the New Jersey shoreline on March 20/21, so an expansion of snow via squalls is possible through the interior Northeast before the impulse moves out of the picture.

If these other strong systems do -not- link with the subtropical jet stream, an area of very dry and increasingly warm or hot air will build from the Desert Regions and Mexico into Texas and the Great Plains during the next two months. The analog forecasts have strong drought and heat signals over the Heartland through the south central U.S. between now and June 1. On the idea that an occasional phase with the southern branch occurs, then those living over and east of the Mississippi Valley are in for a very turbulent spring with cases of intense convection and sudden, usually temporary, temperature changes from warm to cold and back again.