Rain Wrapped Tornado
A severe weather event may be taking shape across the southern United States late tonight and tomorrow. The bulk of the severe weather will run in the ArkLaTex eastward toward the Mississippi Delta. Strong storms are possible here in Acadiana with damaging winds and isolated tornadoes possible. Heavy rains will accompany these storms, so rain wrapped tornadoes during the darkness hours can be a recipe for disaster. Many of the deadly tornado outbreaks we see during the winter months occur overnight, in areas not accustomed to tornado activity this time of year.
Several things are coming together for this weather scenario:
The moisture source will be the Gulf of Mexico. Already this morning we’re seeing the moisture riding northward on strong southerly winds near the surface. Dew Points today have risen a good 10 degrees over the last 24 hours across southern Louisiana and southeast Texas. 66 degree dew points are noted as far north as Dallas, and 70+ degree dew points are seen across the Gulf to the Texas coastline, and just offshore of Louisiana. Air temperatures are expected to push into the low to mid 70s across the region by this afternoon.
A strong upper level low is noted over the four corners states heading east. Another spin is noted near the Montana/Canada border heading southeast forcing a surface low pressure area to develop over the Texas panhandle. That surface low (along with the Canadian deal) will pull cold air at the surface down through the plains, generating a strong cold front. That cold air will collide with warm moist air that will be in place over Texas, and eventually Louisiana. At the same time the upper level system over the desert southwest will reach maturity around midnight over eastern Texas. A squall line that will form ahead of the front this afternoon over central Texas will strengthen as it moves eastward peaking out at the Texas/Louisiana state line very early Thursday. As the upper low from the west matures, it will swing toward the northeast bringing the severe storms through the ArkLaTex. The lower end of this line of storms has the potential to be strong to severe as strong winds in the lower levels will persist over Acadiana. Right now damaging winds are possible here in Acadiana, while the main tornado threat will remain farther north. There are some indications though, that isolated storms well ahead of the squall line could have the potential for rotation, so there’s your isolated tornado threat for Acadiana. Keep in mind these storms are possible several hours before the main line of storms blasts through.
Here’s the timing. Scattered showers will develop during the midday hours. Some thunderstorms are possible as we head toward the evening. Rain chances will increase after midnight. Midnight to sunrise will be the time frame for the “isolated rotating thunderstorms”. I find these situations more dangerous because they have a mind of their own, develop quickly, and are well ahead of the main line. The cold front will force the squall line into western sections of Acadiana just before daybreak. That line will progress through the area and should move out by early afternoon. The rains will end, the front will follow, and temperatures will drop. Expect the temp to climb into the mid 60s early in the day with temperatures falling into the upper 40s by sunset. Rainfall totals are expected to be in the 1-2 inch range.
Skies will clear Christmas Eve night and Santa will have a brisk northerly wind to ride in on from the North Pole. Christmas morning will be clear and chilly with temperatures starting in the mid to upper 30s. Sunshine Christmas Day should bump the temps to the mid 50s, but cold air advection (movement of air) will continue over the weekend. That cold air will be going over a large area of snow pack that will blanket most of the plains and Midwest tonight and tomorrow, so the air will stay refrigerated. Below normal temperatures are expected to last into next week with a few areas touching the freezing point this weekend and early next week. Rain chances will be slim to none Saturday through Tuesday.
Chris and I will be watching the radars closely. It looks like we’ll be meeting during the overnight hours if severe weather coverage is needed. Stay tuned.
StormTeam3 Meteorologist Dave Baker
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