AUSTIN, Texas — Heavy rainfall will bring a serious flash flooding threat across a broad corridor from Texas eastward into Alabama through Thursday and Friday, and the danger it carries is not limited to the rain itself. More than 50 percent of all flood fatalities are vehicle-related, and the message from forecasters heading into this event is direct: you never know how deep the water is or whether the road beneath the surface has been washed away or compromised. Turn Around, Don’t Drown.
The Excessive Rainfall Outlook — Thursday and Friday
The NOAA Excessive Rainfall Outlook for Thursday and Friday shows two overlapping risk zones that track the flash flood threat from west to east across the southern tier:
Thursday — Central Texas Flash Flood Risk: The Thursday risk zone is centered over central Texas, covering the Austin and San Antonio corridor and extending westward toward the Hill Country and eastward toward Houston. This zone carries a 15% risk of rainfall exceeding flash flood guidance within 25 miles of any point — a meaningful probability for a region where the terrain, soil type and urban drainage infrastructure create flash flooding conditions rapidly when heavy rainfall rates exceed one inch per hour.
The Texas Hill Country west of Austin and San Antonio deserves specific attention. This region is one of the most flash-flood-prone landscapes in the United States, where shallow soils over limestone bedrock cannot absorb heavy rainfall and runoff channels into creeks and rivers with extreme speed. Flash flooding in the Hill Country can go from dry creek to raging torrent in minutes, with flood waters traveling far downstream into populated areas before any warning can be issued upstream…