The folks up at the Storm Prediction Center in Norman have indicated a severe thunderstorm watch will be needed shortly for portions of the Concho Valley, Central Texas, North Texas, and perhaps Northeast Texas. Thunderstorm initiation is expected to occur within the next two hours near a slow-moving cold front located from near San Angelo northeast to Gainesville. The strongest of these storms will likely be severe with a risk of hail up to the size of golfballs and localized damaging wind gusts. These individual storms will generally move off to the the northeast, while the ‘line’ itself slowly moves south. By late afternoon the line may start to pick up southward momentum with a squall line developing. The risk of damaging winds would increase with any organized squall line that develops, in addition to large hail.
Mesoscale Discussion 0476
NWS Storm Prediction Center Norman OK
1217 PM CDT Mon Apr 10 2017
Areas affected…Parts of central through northeast Texas and
adjacent southeast Oklahoma
Concerning…Severe potential…Watch likely
Valid 101717Z – 101945Z
Probability of Watch Issuance…95 percent
SUMMARY…Thunderstorm development, accompanied by the risk for
severe hail and locally strong surface gusts, is expected to
increase across parts of central through northeast Texas (and
adjacent areas of southeast Oklahoma), including much of the
Dallas-Fort Worth Metroplex, through 2-4 pm CDT. A watch will
likely be needed.
In addition to the severe weather potential, we’re going to see a threat of flash flooding develop this evening and tonight in parts of Central Texas. Storms that develop this afternoon will eventually congeal into a squall line. This squall line will likely lose most of its momentum by this evening in portions of Central/South-Central Texas. Where that line stalls out we’ll start seeing training storms. Think of training storms as storms that just keep moving along a train track, dumping heavy rain. This is the kind of setup where we could see 5 to 7 inches of rain in a very short period – like two or three hours. If that occurs, we’re going to see dangerous flash flooding develop over a localized area. We can’t say for sure where that will be just yet, but we are likely going to see problems with flooding develop rapidly tonight in portions of Central and South-Central Texas. Flooding kills more folks than all modes of severe weather combined, and we have a very bad flood history in this part of the state.
I’ll leave you with a simulated radar output from one of this morning’s high resolution rapid refresh (HRRR) model runs. The radar probably won’t play out exactly as depicted, but it gives you a general idea on timing for your area. You can also see the line stall out over portions of South-Central Texas this evening – a big concern for flooding.