Flash flood warnings were issued Wednesday for sections of coastal southeast Texas hit by Hurricane Harvey last summer.
Heavy rain was falling in Victoria, Corpus Christi and McAllen, where hundreds of migrants seeking entry into the United States await processing at a detention center. There were no immediate reports of problems at the center because of the rain.
Flash flood warnings were issued for southeast Hidalgo and northwest Cameron counties, along the Mexican border, the weather service said.
"This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!" the weather service said. "Turn around, don`t drown when encountering flooded roads. Most flood deaths occur in vehicles."
Flash flooding was reported in Hidalgo County, already saturated with 4 to 6 inches of rain. Meteorologists predict another 2 to 4 inches of rain Wednesday across southeastern coastal Texas.
The warnings expired at 2:45 p.m. Central Time, as the rainfall weakened.
"Things are looking better over the next few days," CNN's weather team said.
A 91-year-old woman had to be rescued when water rose in her home, the City of McAllen tweeted. Video from San Juan showed water almost covering vehicles and motorists being rescued in kayaks. Many law enforcement agencies warned motorists not to drive into water-filled streets.
McAllen officials also posted a photo showing a large section of sunken pavement where floodwater had receded, noting, "There are several sinkholes in the area."
Rain to continue Thursday
Flash flood watches are also in effect for areas south of Houston to Brownsville, at the Mexican border, with flash flood warnings popping up as storms flare, CNN meteorologists said.
The Corpus Christi office of the weather service tweeted that 12.89 inches of rain had fallen between 7 a.m. Monday and 7 a.m. Wednesday in the city's northwest section.
Showers and thunderstorms are forecast to continue through Thursday, the National Weather Service tweeted.
The system producing the rainfall is not a tropical system, CNN meteorologist Brandon Miller said, but it does contain ample amounts of tropical moisture and is dumping it at rates normally found in a tropical storm.
'Nervous about losing their stuff again'
Rain also continued to fall near Houston, causing more misery for places still reeling from the impact of Hurricane Harvey last summer. Flash flood watches issued Wednesday just southwest of Houston could be "extended eastward during the day," the weather service's local office said.
North of Houston the city of Port Arthur, which along with Beaumont was devastated in August by Harvey's floods, was swamped again Tuesday by the weather system now pummeling points south.
Video from Port Arthur showed streets turned into raging rivers as cars slowly made their way through them.
The storms conjured memories of last summer's flooding, said Damion Robertson.
"It's concerning. A lot of people just lost a lot of houses ... over Harvey," Robertson told CNN affiliate KBTV. "So, a lot of people are probably nervous about losing their stuff again."
Larry Wolf, also of Port Arthur, said his home has flooded twice.
"I'm to the point where I'm 75 years old," he told KBTV. "I can't do it anymore."
The Beaumont Port Arthur airport "broke daily rainfall record (Tuesday), where 5.89 inches of rain fell in a 24-hour period, causing flash flooding in the area," CNN meteorologist Michael Guy said Wednesday.
"While rainfall totals will not even come close to the amount that Harvey left in its wake, the region could still suffer damage from flash flooding, downed trees and travel disruptions," he said.
Harvey dumped record rainfall of more than 60 inches over just a few days after it hit southeast Texas as a Category 4 storm. Dozens of people died and millions were affected in and around Houston, the nation's fourth-largest city, and along the Gulf Coast.
Following Harvey, federal officials began controlled releases of water from dams and reservoirs. But the move backfired, as there were homes and businesses in the water's path. The plan was designed in the 1930s when the city was much less populated.
CNN affiliate KTRK reported that Lake Houston will be lowered 1.5 feet to prevent any additional runoff from the reservoir.
"We did it a time before and it mitigates the risks and it works," Houston Mayor Sylvester Turner told KTRK.