...HEADLINE...Isolated Flash Flooding concerns tonight for the northern half of South Central Texas...
...AREA OF CONCERN...Northern half of South Central Texas...mainly north of a line from Rocksprings...to San Antonio...to Hallettsville. See the attached graphic.
...IMPACTS...Isolated rainfall totals that could exceed 4 inches. Widespread rains of 1-2 inches are possible across portions of the Hill Country and northern sections of South Central Texas. Can't rule out an isolated strong thunderstorm gust in excess of 50 mph especially in the Hill Country.
...TIMING...Overall threat time will be from 6pm through 6am.
...DISCUSSION...A stalled out front over north Texas has been producing heavy rains over the northern part of the state for the past few days. An upper level disturbance over the TX/OK panhandles will be moving across North Texas today and tonight, helping to trigger additional thunderstorms. A cluster of storms that formed over West Central Texas last night has weakened significantly and is moving across South Central Texas right now. The mostly cloudy conditions and scattered rain showers will last most of the morning for us. We are expecting a repeat tonight, with a cluster of storms likely forming west or northwest of South Central Texas, and then pushing E/SE through our area. Could be as early as the evening hours...could be as late as 3 am. The models have been consistent in forming these storms...but has been inconsistent on the timing. So unfortunately at this point in the forecast I can't give better timing to when the possible locally heavy rain could move in.
Most areas remain very dry, but a few lucky residents have picked up some higher totals the past week. So widespread rains are very welcome, but at the same time, quick downpours, high rain rates, and totals exceeding more than 2 inches could lead to some isolated flash flooding, both in the urban areas and also a few spots in the northern Hill Country. In a few areas that could exceed 4 inch rain totals, the chances of seeing some isolated flash flooding will increase. The atmosphere right now has a lot of moisture in it, we measure that moisture content with the weather balloons. Because of that, you can expect tropical like downpours and excessive rain rates, could be as high as 3-4 inches per hour in some spots. Even if that occurs over 15 min...you are still going to see a lot of quick runoff and minor flooding.
Overall the system should be exiting the area Friday morning, but can't rule out some lingering rain activity on Friday. The majority of the threat however should have already passed. Stay vigilant during the day today and tonight in watching the weather forecast and radar to keep a good situational awareness in case we have to issue any Watches/Warning/Advisories. Remember...Turn Around...Don't Drown.