Severe Weather Later Today/Tonight

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Merry Christmas, but as I said on ABC 3340 last night, I feel like the Grinch with the weather pattern that is unfolding on what should be one of the nicest and most peaceful days of the year!

The trough that we have been showing coming out of the southern Rockies is doing just that this morning as it generates a surface low over Southeast Texas that will move quickly across Northeast Mississippi this evening reaching Nashville, TN, on Wednesday morning. Parameters continue to come together for a significant weather across the South Central and Southeast US today and tonight. SPC has outlooked a major chunk of the the Southeast US from East Texas to western South Carolina for severe weather today with a moderate risk from about Houston to Tuscaloosa to Mobile. It is in the moderate risk area that potentially long track tornadoes may occur. But for all of the risk area, we anticipate seeing all modes of severe weather including large hail, damaging wind, and tornadoes.

The environment across Central Alabama is somewhat chilly this morning as we dipped into the middle 40s with fog an issue across the eastern half of the state. But just about all computer guidance suggest that the surface low will deepen and move rapidly from Southeast Texas today into Middle Tennessee by Wednesday morning. This will put much of that slight risk area into the warm sector with a two-fold weather threat with potential for discrete supercell thunderstorms as well as a squall line. A severe thunderstorm watch is in effect for portions of Southwest Louisiana and East Texas, and I would expect to see tornado watches issued later this morning continuing into the early morning hours of Wednesday. Note, as I was writing this I see that SPC issued a tornado watch, the first of the day, for sections along the coast of South Central and Southeast Louisiana.

This continues to be a low CAPE, high shear situation, so the severe weather threat is significant. You can read James Spann’s discussion below this one. Significant Tornado Parameter or STP brings 4 to 6 values into Southwest and Central Alabama this evening, and an STP of 1 or higher is significant, so these projections are way up there.

Another big problem especially for travelers will be the winter weather caused by this storm system from Oklahoma across Arkansas and the Mid-South area all the way into New England. This is likely to cause a lot of travel issues both for automobiles and airplanes, so any travelers need to consider these elements as you make plans to travel late today and Wednesday.

As the surface low moves into Tennessee and Kentucky on Wednesday, cold air will surge into Central Alabama bringing a raw day to the area for Wednesday. I expect temperatures to hold steady or fall through the 40s with the high occurring around midnight or 1 am Wednesday and the low occurring around 11:59 pm Wednesday night. This presents us with the age old problem of cold air arriving as the moisture is leaving, but I think there is enough evidence that the precip will briefly include some light wintery precip in the form of rain/snow mix or flurries especially for the areas north of Birmingham. 850 millibar temperatures are certainly supportive of that IF there is enough moisture.

We dry out Thursday and Friday, but the next system is poised late Friday to bring rain to the area on Saturday, maybe beginning late Friday night. This looks a lot like our current pattern with the exception of being much weaker. So I don’t think we’ll see a severe weather threat for next Saturday based on what I see right now.

While we stay seasonal in our temperatures with values at or slightly below 30-year averages for this time of year, the upper flow goes southwesterly which will allow Pacific moisture to come into our area. This could present us with a wet looking start to 2013.

The big message from looking into voodoo country is that the weather systems will be coming at us about every 2 to 3 days for the foreseeable future. There does not appear to be any extremely cold air coming our way yet.

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Please have a way to hear weather warnings today. The ABC 3340 Weather Team has made plans to cover this event, so you can tune into the Blog or the television station for the latest information. Merry Christmas and Godspeed.

-Brian-

Category: Alabama's Weather