Earlier this week, it was thought that heavy rainfall could begin in San Antonio by Wednesday night. But forecast models since then have shown that the incoming cold front will be delayed by around 12 to 18 hours, meaning that the highest chances for rain are now expected to arrive midday Thursday.
The flood watch issued for South-Central Texas will still go into effect at 7 p.m. Wednesday. However, mostly dry weather is expected throughout the region until midnight, especially over the Interstate 35 corridor. An isolated shower or storm remains possible, but rain chances on Wednesday will only be around 20%.
After a few scattered storms become possible overnight, a strong line of thunderstorms is likely to start pushing into the Hill Country by sunrise on Thursday. This line will continue southeast, likely moving close to the San Antonio by the late morning and early afternoon.
The exact timing for the onset for heavy rainfall is still uncertain, but San Antonio’s greatest chance of storms will occur between 10 a.m. and 4 p.m., as the slow-moving line of storms moves across Interstate 35.
A brief break in the rainfall is possible by Thursday evening, especially between 6 p.m. and 10 p.m. However, many weather models do show the potential of storm redevelopment late Thursday night and into early Friday, which could trigger a flooding risk during the Friday morning commute.
For most of the region, the rainfall expected over the next 48 hours will be beneficial. However, flooding could become a major concern in the isolated pockets across the region that pick up 5 to 8 inches of rainfall.
The storms Thursday morning may also bring a risk of damaging wind gusts of up to 60 mph, as well as small hail and frequent lightning. This activity could result in power outages through San Antonio and the surrounding area.
Scattered rainfall will stay possible in the region over the weekend, with about a 50% chance of rain Saturday, followed by a 20% to 30% chance on Sunday. The flood threat, though, will decrease significantly, as most rainfall will be light.