The National Weather Service in Brownsville has issued a tornado watch for the entire Rio Grande Valley.
The watch will remain in effect until 10 p.m. this evening.
A tornado reportedly touched down near the Brownsville-South Padre Island International Airport.
A flash flood warning remains in effect until 11 a.m. for west central Cameron County and southeastern Hidalgo and southwest Willacy County.
The NWS reports Doppler radar indicated heavy rain across the warned area. Flash flooding is ongoing or expected to begin shortly.
A flash flood watch remains in effect for the entire Rio Grande Valley until this evening.
Heavy showers and thunderstorms associated with Tropical Storm Hanna will produce 6 to 12 inches of rainfall, with up to isolated 18 inches of rain possible.
Low-lying and poorly-draining areas as well as urban locations will experience flooding. Heavy rainfall in a short period of time will cause creeks and arroyos to overflow. Driving will be difficult, and motorists are urged to find alternative routes if flooded roadways are encountered.