EF1 tornado in Union Parish, Louisiana

NWS Storm Survey Team concluded that the damage outside of Downsville, Louisiana on December 21st was consistent with that of an EF1 tornado. Damage consisted of damage to several trees and a barn. The tornado had a path length of just under a mile with a path width of 75 yards. Winds were estimated to be near 90 mph during the height of the storm.

A vigorous upper level trough moved out of old Mexico and ejected out in the Oklahoma and Texas Panhandle during the late morning hours of Saturday, December 21st. As the trough began to fill and lift out, it took on a negative tilt which helped to increase lift across the region during the afternoon. Meanwhile, closer to the surface, the leading edge of a very shallow but cold airmass, in the form of a cold front, was moving across Northeast Texas into Southwest Arkansas. This put nearly all of Northern Louisiana and South Central Arkansas in a very strongly sheared warm sector. Low level shear was maximized just ahead of the cold front as it slowly moved east during the afternoon hours. Deep layer shear was in the order 60kts from the southwest and this resulted in a broken squall line that moved quickly through the region during the afternoon of the 21st. A tornado also developed along the leading edge of the squall line in Northeast Louisiana with some wind damage reported. Otherwise, widespread wind damage was observed with mostly straight line winds across much of Northern Louisiana and South Central Arkansas as well as the southern two thirds of Northeast Texas.