A statement from the National Weather Service extended the flash flood watch for Austin County through Saturday afternoon.
"A slow-moving, upper-level low-pressure system over Central Texas will pull extremely moist air from the Gulf of Mexico in Southeast Texas tonight," the release says. "As the system nears the area, a line of showers and thunderstorms will develop and race eastward across the area. The line of storms will cross the area between 3 a.m. and 9 a.m. early Saturday morning."
The release said the rainfall rates could exceed two inches an hour, averaging an additional one to three inches in Southeast Texas and about five inches in areas with isolated storms.
Counties affected included Austin, Brazosira Islands, Chambers, Coastal Brazoria, Coastal Galveston, Coastal Harris, Coastal Matagorda, Colorado, Fort Bend, Galveston Island and Bolivar Peninsula, Montgomery, Northern Liberty, Polk, San Jacinto, Southern Liberty, Waller and Wharton, among others.
"A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation," the release says. "You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued."