Precipitation is already moving into the area early this morning. While temperatures are in the mid-30s across the region, I suspect the majority of this precipitation is falling as rain. With ground temperatures above freezing, we would need colder air just above the surface for any type of winter precipitation to occur. A weather balloon launch from the National Weather Service in Lake Charles shows temperatures steadily above freezing going up a few thousand feet into the atmosphere. For this reason, mostly rain showers will be possible through the morning, although it wouldn’t surprise me to get a few sleet reports, especially across central parts of the state.
Another round of precipitation will come into the area later on tonight. This will occur as a surface low develops across the west-central Gulf of Mexico, moving east-northeastward across the northern Gulf. Meanwhile, a shallow layer of colder air will be marching southeastward into southeastern Texas and Louisiana. For winter precipitation to occur, temperatures have to be at or near freezing at the surface (32-35F), but more importantly, temperatures aloft have to be below freezing through a deep enough layer of the atmosphere. You also need good atmospheric lift in the “snow growth” zone in the mid-levels of the atmosphere.
Analyzing models, these factors will all come together across central and northern portions of the state later tonight. A WINTER STORM WARNING is in effect for northern portions of Louisiana, closer to I-20, while a WINTER WEATHER ADVISORY is in effect for central portions of the state, including Vernon, Rapides, and Avoyelles parishes.
A wintry mix could be possible further south, namely northern portions of Beauregard, Allen, Evangeline, and St. Landry–however, ground temperatures will be well too warm for any type of accumulation in these areas. Further south, closer to I-10, an all-rain event is expected as temperatures will be too warm at the surface, and aloft, for any type of winter precipitation to reach the ground. In the winter storm warning region, snow accumulations of 2-4 inches will be likely with isolated higher amounts!
At the very least, we’ll get to see some cool pictures from northern Louisiana on Monday. Speaking of Monday, expect a cold day with highs only in the mid-40s. A light freeze likely Monday night/Tuesday morning.