Winter Weather in Upper St. Martin, Louisiana

A powerful and deep upper level trough of low pressure moved quickly across Texas and Louisiana on Friday, December 4, 2009. At the same time, a strong area of surface low pressure developed in the western Gulf of Mexico. Meanwhile, a cold Arctic airmass filtered southward through the southern United States. All of these factors combined to produce a large area of rain along the Texas coast during the morning hours, which then spread northeastward across southwest Louisiana during the late morning and afternoon hours. As temperatures gradually cooled both at the surface and aloft, the rain began to mix with and eventually change over to snow from west to east across the area from the afternoon through the evening. Snow fell for many hours across central Louisiana along and north of the Highway 190 corridor, but only for a few hours south of Highway 190.

Total snow accumulations across southwest Louisiana ranged from just a dusting near the coast up to 3 inches across central Louisiana. The heaviest amounts occurred in three separate mesoscale bands that stretched from southwest to northeast, with one band stretching from northwest Beauregard Parish into Vernon Parish; the second along a line from southeastern Beauregard Parish into southern Rapides Parish; and the third from southern Jefferson Davis Parish into southeastern Avoyelles Parish and on into Mississippi.

Snowfall totals included 3.0 at Eunice, 2.5 at Fort Polk, 2.5 at Rosepine, 2.0 at Anacoco, 2.0 about 5 miles ENE of Dequincy, 2.0 at Elmer, 2.0 at Leesville, 2.0 at Ville Platte, 1.5 at Lacassine, 1.5 at Welsh, 1.0 at Alexandria 911 Center, 1.0 at Bell City, 1.0 at Carencro, 1.0 at Plaisance, 0.8 at Jennings, 0.5 at Lake Arthur, 0.3 about 5 miles SSE of Dequincy, 0.3 about 7 miles southwest of Boyce, 0.3 at Lafayette, 0.2 at Alexandria Int'l Airport, 0.2 at Lake Charles, and 0.2 at Moss Bluff.

This became the earliest measurable snowfall on record at both Lake Charles (0.2) and Lafayette (0.3). The previous record was set just one year prior on December 11, 2008.