Let me start out by saying we haven’t had too many overnight severe weather threats in Texas over the past couple of years. Combine that with the notion that we don’t get severe storms in the fall and there is the potential for folks to be caught off guard Monday Night and Tuesday. Fall is our secondary severe weather season in Texas and we have had significant severe weather outbreaks in the overnight hours back in the 2000s. I’m not saying this is going to be a major event for Texas but we are going to have the ingredients coming together for a very busy period starting Monday evening continuing into Tuesday. This means severe weather will be occuring when most folks are asleep and we really need to stress that concern. Have a severe weather safety plan ready and especially have a way to receive severe weather warnings Monday Night and on Tuesday.

eveningoutlook

The current severe weather outlook places the eastern two-thirds of Texas in a risk beginning Monday evening. We’ll initially have discrete supercell thunderstorms develop in the Texas Panhandle and West Texas. These initial storms will be capable of producing large hail, damaging wind gusts, and tornadoes. After a few hours we’ll see those discrete/first storms and new storms congeal into a squall line. This squall line will move east into Northwest Texas, the Concho Valley, and Big Country by late Monday evening. The line of storms will have a slightly lower hail threat but an increased damaging wind threat. Isolated tornadoes will remain possible especially in enhanced cells of the squall line. Any sustained cells that develop ahead (or east) of the squall line will have to be watched for tornado potential. CUrrent timing has the squall line approaching the Interstate 35 corridor from the Red River south through North and CEntral Texas during the 3 to 6 AM timeframe Tuesday. Damaging wind gusts, pockets of hail, and isolated tornadoes will continue even in the overnight hours. The line of storms will continue to move east on Tuesday bringing a severe weather threat to Northeast Texas, East Texas, and Southeast Texas. We may see localized flooding in Northeast Texas.

Winds at 500 millibars at 12 AM Tuesday from the 0Z NAM. Speed is in knots.

Winds at 500 millibars at 12 AM Tuesday from the 0Z NAM. Speed is in knots.

Winds at 850 millibars 12 AM Tuesday. This is around 5000 feet above sea level. Also from the 0Z NAM.

Winds at 850 millibars 12 AM Tuesday. This is around 5000 feet above sea level. Also from the 0Z NAM.

Surface based instablity values at midnight Tuesday from the 0Z NAM. The instablity axis is moving east with the line of storms.

Surface based instablity values at midnight Tuesday from the 0Z NAM. The instablity axis is moving east with the line of storms.

These three images are off the just out 0Z North American Model (NAM). The first two impacts show wind fields at midnight on Tuesday while the third image is of surface based instablity at the same time. What I think is most noteworthy are the last two images. You can see a ‘virtual’ squall line depicted by the model across Northwest Texas and the Big Country. Winds ahead (east) of the squall line are blazing with a low level jet of 65-75 MPH! Those winds veer to the southwest with height providing an insane amount of wind shear for Monday Night and Tuesday Morning. That kind of wind shear isn’t all that unusual with dynamic storm systems in the fall and winter months. WHat makes this setup concerning is that we’re going to have a sizable amount of instablity in place at the same time. More than enough instablity with a extraordinary amount of wind shear and moisture all spells the potential for severe weather Monday Night into Tuesday morning. Low-level wind shear will be very strong and that’s why we’re talking about a tornado threat. A linear mode (squall line) will reduce some of the tornado threat Monday night but definitely not eliminate it. The strong thunderstorms will also have the potential to ‘mix down’ the strong winds aloft and thus we’ll also be dealing with a fairly substantial damaging wind threat. Nothing is written in stone and I’d expect spatial and timing changes as we get closer to Monday.

This does have the potential for be one of our more significant overnight severe weather risks we’ve seen in some time in Texas. I encourage you and your family to have and practice your severe weather safety plan. Plan on having a way to receive warnings Monday Night into Tuesday morning. Most smartphones will alert you to tornado warnings via the Wireless Emergency Alert System – the same way you get flash flood warnings and amber alerts. NOAA Weather Radios and other smartphone apps are also great ways to get warnings. Don’t count on getting your warning off social media in real-time as algorithms may display them several hours later in your newsfeed!