Compared to the forecast update we posted early this afternoon there have not been many changes with our upcoming severe weather threat. An Enhanced Risk of Severe Weather (Category 3) is in place across the eastern Texas Panhandle, Northwest Texas, Big Country, and much of North Texas. Surrounding it is a Category 2 severe weather risk that includes the South Plains, Concho Valley, Hill Country, Central Texas, Southeast Texas, East Texas, and Northeast Texas. The difference in risks mainly applies to how widespread we expect the severe weather threat to be. The same kind of severe weather is possible in either risk zones.
The first arriving model this evening continues to show thunderstorm initiation in the eastern Texas Panhandle and West Texas around 5 to 6 PM Monday. Those inital storms will likely be supercellular with a risk for large hail and a few tornadoes. As the upper level storm system continues to move east we’ll see a line of storms quickly fire up by mid Monday evening. The threat for damaging straight line wind gusts will be enhanced with the line of storms. Embedded tornadoes could occur in stronger cells in the line or where we see mesoscale factors come into play. The line of storms will quickly move east and by about 2 AM Tuesday should be approaching Interstate 35 from the Red River south to Central Texas. I expect the line to still be severe at this point with damaging wind gusts and brief tornadoes. Once east of Interstate 35 the line will impact Northeast Texas, East Texas, and Southeast Texas into the morning hours on Tuesday.
We’ll have to closely watch for any cells that can develop ahead of the squall line tomorrow night. Wind shear values will be about as high as you’ll see in a severe weather setup. The overall linear mode of the squall line will partially limit the tornado threat. However if we get one or two discrete cells ahead of the line they could have an enhanced tornado threat. The good news is those cells wouldn’t last long because the line will catch up and ingest them. The fast movement of the line will prevent more than a limited flooding threat – but heavy rain will fall in a short period of time. It could be a dicey morning commute on Tuesday morning for folks along Interstate 35 and points east.
That’s all for now! The Storm Prediction Center will issue a new severe weather outlook around Midnight. We’ll post it shortly thereafter. I’ll leave you with a few resources that contain further information on the upcoming storm system and what you can do to prepare.
— NWS San Antonio (@NWSSanAntonio) November 15, 2015