Several periods of rain and thunderstorms are forecast across the region starting this afternoon, continuing through the middle of next week. Some of the thunderstorms over the next couple of days could be severe, producing large hail and damaging winds.
A warm, humid and slightly unstable air mass is currently in place across Central and South Texas. Morning observations indicate a fairly strong inversion, or stable layer, is in place in the lower to middle atmosphere. This stable layer will likely limit the development of showers and thunderstorms for most areas to the east of Interstate 35. However, areas to the west of Interstate 35 could see the development of scattered thunderstorms late this afternoon and evening, where the stable layer is much weaker. The focus for thunderstorm development is expected to be the dry line. As of late this morning, the dry line stretched from near Lubbock to Midland to Fort Stockton. It is predicted to push east to the Concho Valley region later this afternoon. Conditions appear favorable for scattered thunderstorms to develop along the dry line, with the storms tracking to the east-northeast. Some of these storms may move over parts of the Hill Country late this afternoon and evening. The northern Hill Country, between San Saba and San Angelo, looks to have the highest probability for rain and thunderstorms. Should thunderstorms develop, they may quickly become severe, producing large hail , damaging winds and isolated tornadoes. The Storm Prediction Center has placed the area west of I-35 under a Slight Risk for severe thunderstorms this afternoon and tonight. The potential for thunderstorms is forecast to decrease after midnight tonight. For areas that do see thunderstorm activity, most totals should average around a half inch, with isolated heavier totals. Today's sky is expected to remain mostly cloudy. Expect a high temperature near 90 degrees.
At 2 pm, the Storm Prediction Center issued a tornado watch for parts of western and northern Texas until 10 pm Thursday evening. The watch extends south into the northern Hill Country and includes San Saba, Lampasas, Mills, McCulloch, Brown and Coleman Counties. The Austin area and the rest of the Hill Country are not included in this tornado watch.
A very similar weather situation is forecast across the region Friday. The focus for thunderstorm development will primarily be across the Hill Country, close to the position of dry line. Some of these thunderstorms will again have the potential to become severe. The most favorable time period for thunderstorms looks to be in the late afternoon and evening. For locations that do see rain, totals should average around a half inch. Meanwhile, most areas to the east of Interstate 35 will generally stay mostly cloudy and dry. High temperatures will be near 88-90 degrees.
A more widespread coverage of rain showers and thunderstorms is forecast to occur across the region Saturday into Sunday when a weak cold front slowly sags southeast out of North Texas. Conditions appears favorable for the development of rain showers and scattered thunderstorms out ahead of the cold front beginning Saturday morning. Additional rain showers and thunderstorms look to continue Saturday night and Sunday behind the cold front. The threat for severe thunderstorms during this period will not be all that high. But due to the slow movement of the cold front and the presence of a very moist atmosphere, significant totals of rain will be possible Saturday into Sunday. Rainfall forecasts suggest widespread totals of 1-2 inches will be possible across the region, with isolated heavier totals. Do note that if the cold front moves slower than currently forecast, these totals could go higher. The rain is forecast to decrease in coverage across the Hill Country and Central Texas regions Sunday afternoon but continue across the coastal plains region. A 20-30 percent chance for mainly light rain showers is forecast Sunday night.
Another chance for rain and thunderstorms is forecast to develop Monday as a trough of low pressure moves east out of Mexico. This system is expected to quickly pull moisture north from the Gulf of Mexico, resulting in the development of rain showers and thunderstorms. The most favorable period for rain is expected to occur Monday night and Tuesday, with the rain tapering off Tuesday night. Rainfall from this system is forecast to generally average between 0.5 and 1 inch. This will be followed by sunny and dry weather next Wednesday through Friday.
Pasted below is the National Weather Service's rainfall forecast for the next 7 days. In general, the forecast calls for totals of 3-4 inches across the northern and western Hill Country, with totals of 2-3 inches at most other Hill County locations. Totals for areas along and east of I-35 should average between 1 and 3 inches.NWS rainfall forecast for the period 7 am Thursday through 7 am next Thursday: