A tornado touched down near Interstate 10 in northwestern San Antonio on Wednesday as slow-moving storms kept drenching South Texas; no injuries were immediately reported.
10 to 20 inches of rain could fall in some areas through Thursday evening, with Uvalde County already seeing up to 16 inches and flash-flood warnings posted near the Mexico border and west of San Antonio.
Dozens of high-water rescues followed Tuesday's flooding: Uvalde officials reported at least two dozen water rescues, while Texas game wardens said they pulled nine people to safety.
Gov. Greg Abbott declared disasters in dozens of counties as shelters opened in Uvalde and Sabinal and Kerr County alerted camps and retreat centers along rivers vulnerable to flooding.
Meteorologists said a stagnant low-pressure pattern fed by Gulf and Pacific tropical moisture is driving a mid-summer setup that can recur in Texas about once every five years.