Scattered to numerous showers and thunderstorms will continue into the overnight hours across the Big Country into western North Texas. Focal points for development tonight will be residual boundaries generated by thunderstorms this afternoon. A low level jet will also increase tonight helping to pump moisture in from South Texas and the Gulf of Mexico. That LLJ will act as fuel to keep the heavy rains going tonight. What we will likely see happen tonight is a rather potent band of heavy rain oriented from north to south. The band won’t make much progress west or east but will simply sit over the same area for hours at a time. Meanwhile as the low level jet pumps fuel (moisture) in the heavy rains will continue to fall. This type of convection is called ‘training’ and helps produce some of our more prolific flash flood events.
Flooding has already been a major issue in the Concho Valley and Big Country today. Abilene set a all-time record for most rain in one day at 11 AM. With new development expected this evening and tonight its likely Abilene will see more rain. Short-term high resolution weather models indicate the band of heaviest rain could push a bit further east towards I-35/I-35W tonight. For that possibility the National Weather Service in Fort Worth has extended the Flash Flood Watch further east to include locations just west of the D/FW Metroplex. A flash flood watch means conditions will support the possibility of flash flooding.
I’m fairly confident we will see that band of heavier rain set up in western North Texas this evening and tonight. Not only will western North Texas be under the gun for potential flooding – so will Northwest Texas and our neighbors in Southern Oklahoma. Remember that with copious amounts of moisture in place we could easily see one to three inch rainfall totals an hour out of the heaviest convection. We do have some leeway because of drier weather over the past few weeks – but with that kind of rain it won’t take long to start having issues with flooding.
Based on the current data we should see the heaviest rain and flooding risk remain just west of D/FW. However any shift east would result in an increased flooding risk for the D/FW Metroplex. Many low-lying areas and construction zones have issues with even a typical summer downpour anyway. Remember that when you drive up on water crossing a road to turn around. Not only could you down but you could flood your vehicle out and be in for one hefty bill.