The National Hurricane Center says it is monitoring Tropical Depression Nine in the Gulf of Mexico.
"A Tropical Storm Warning has been issued for portions of south Texas," the NHC advised.
Forecasters say expect the depression could become Tropical Storm Harold before it makes landfall Tuesday.
"The depression is moving fairly quickly to the west," the hurricane center said. "A continued quick west or west-northwest motion is expected, taking the system over southern Texas by midday Tuesday."
"Heavy rainfall from the depression is expected across South Texas on Tuesday and Wednesday," the Hurricane Center warned. "Tropical storm conditions are expected in the warning area and are possible in the watch area beginning early Tuesday."
