Severe Storms Tonight

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It’s December in Central Alabama, so when you step outside this morning you will get the feeling that this is not the typical weather for the days approaching Christmas. In fact, temperatures will be warm enough today to potentially tie or set new record highs. The record high for today in Birmingham is 73 degrees, so with the afternoon highs expected to reach the middle 70s, we could see a new record. You’ll also notice a stiff south to southeast wind which is helping to feed moisture and warmth into the approaching weather system.

Aloft a deep trough it kicking out of northern Mexico while at the surface a nearly stationary front stretches from the Ohio River Valley into Northeast Texas. Along that front there are numerous flash flood watches plus just to the northwest of the front are numerous winter weather watches, warnings, and advisories, so this storm system will be creating some travel problems for those headed out for Christmas travel this weekend. As the upper trough comes out of the Southwest, surface lows will ripple along the frontal boundary. Over the Southeast US and Lower Mississippi River Valley, low level moisture is in place with dew points in the middle to upper 60s with near 70 degree values along the Gulf Coast. This all sets the stage for an outbreak of severe weather across the Lower Mississippi Valley where a moderate risk area extends from just north of Nashville southwestward to near Lake Charles. See the Weather Xtreme Video for the detailed graphics.

The system kicks out later today while the bulk of the trough hangs back to our west. This will create a positive environment for severe weather with damaging wind and tornadoes possible. Low level wind profiles suggest the potential for some tornadoes to be strong. But as James suggests in the post below, we don’t need to be comparing this to April 27, 2011, which was a generational event. And we need to remember that we are in the secondary severe weather season for much of the Southeast US. So this afternoon and evening, we’ll need to watch for the development of super cells ahead of the main frontal boundary, but as the hi-res NAM suggests, the system should evolve into more of a linear event with a squall line moving across much of the northern two-thirds of Alabama tonight and into the morning hours of Sunday. The primary threat with the squall line will be damaging wind but isolated tornadoes will be possible with the line.

Today is the time to do some advance preparedness and make sure that you have a way to get warnings while you are asleep. A NOAA Weather Radio is the baseline, but smart folks will have more than one way to get warnings. Smart phone apps like MyWarn and iMap Weather Radio fit that bill because you set them and forget them, but they are looking out for you.

Because the major trough axis lags behind the active weather, we don’t turn appreciably colder until Monday and Tuesday as the colder air finally arrives with the trough passage. So it means that Christmas will be cold but dry for us. Christmas Day will start out in the middle 20s, but with good cold air advection reaching 50 degrees for the high may be a struggle.

For the Southeast US, the pattern remains somewhat flat while additional disturbances move through the northern tier of the US. With a dry air mass in place, the days after Christmas will be dry with a slow warming trend.

Looking into Week 2, the GFS suggests the start of 2014 could be warm for us with a substantial trough over the western US pumping up the ridge along the East Coast. But this flow, while warm, will also be wet with a nice tap into Pacific moisture.

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Be sure to stay with the Alabama Weather Blog for additional updates as the current weather system unfolds tonight and Sunday. I know that everyone is thinking about the Christmas holiday, but please stay alert to the weather. The timing of the main weather threat will be while folks are sleeping. I expect to post the next Weather Xtreme Video on Sunday morning, though the exact time may be problematic as we staff the Weather Center at ABC 3340. Godspeed.

-Brian-

Category: Alabama's Weather