At least four people died Thursday and another three were missing because of Erin's thunderstorms.
The storms dropped up to 10 inches of rain in parts of San Antonio and Houston. Officials throughout central and south Texas expected more rain Friday, with forecasts of 7 inches in West Texas.
"The ground's already saturated, then with the amount of rain we got today it's just running off and causing flash flooding, so if we get additional rain it will be a major concern for us," said Orlando Hernandez, emergency management coordinator for Bexar County, where San Antonio is located.
In the eastern Caribbean islands of St. Lucia and Martinique, Hurricane Dean tore roofs off buildings and knocked out power. Airports were closed, hotels evacuated and tourists sent to shelters as 100 mph winds swept over the islands. But Dean, the first hurricane of the Atlantic season, appeared days away from the Gulf Coast. Now a Category 2 storm, Dean could strengthen to Category 4 by the time it reaches Mexico's Yucatan Peninsula next week.
"It's so far out, but it's not too early to start preparing," said Katherine Cesinger, a spokeswoman for Texas Gov. Rick Perry. "We have more notice than with Erin. We're glad for that especially since (Dean) is projected to bring some strength."
Overnight rain prompted the evacuation early Friday of three areas along the Medina River and Medina Lake in Bandera County, said Barbara Kincaid, a county dispatcher. About 50 people were evacuated from the Lake Hills subdivision on Medina Lake, she said. Most of the river evacuations were RVs parked along the river. There were no reports of injuries.
The storms in Houston killed three people: two died when a roof over a grocery store's storage unit collapsed. One of those was identified Friday as store employee Daniel Whitt, 29. The other man, a Coca-Cola delivery man, was not identified.
The third Houston victim was a trucker who drowned when his 18-wheeler went into a deep retention pond.
In San Antonio, a 19-year-old man was swept away by floodwaters after he got out of his car. His body was found about three miles downstream.
Authorities were still searching for a woman who was caught in high water near a mall. Two people, believed to be a father and son, were missing in Kendall County after their pickup truck was washed over a bridge and into a creek just as rescuers tried to pull them out, said the sheriff's office chief deputy, Matt King.
Summer storms have poured record rainfall across Texas and parts of Oklahoma and Kansas, with floods killing 22 people since mid-June. One July storm dropped 17 inches of rain in 24 hours and brought Texas out of a more than decade-long drought.
In Mississippi, Gov. Haley Barbour and Federal Emergency Management Agency officials warned 13,000 families living in FEMA trailers since Katrina that they must evacuate in the event Dean hits the Gulf Coast.
"Today people in Mississippi don't need to panic, but they need to think," Barbour said Friday.
Barbour said people should think about where they will go if an evacuation is ordered and how they'll travel. He said people should make sure they have fuel, water, and a source of communication if electricity is lost.
"No government is big enough to do everything for everybody," Barbour said.
The dangers of a slow-moving storm system are well known in Houston, where Tropical Storm Allison stalled for several days in 2001, soaking the flat, low-lying city. After passing Houston, it returned, dumping about 20 inches of rain in eight hours. About two dozen people died, most of the city was without power and entire neighborhoods were destroyed.
Still, state and local officials said Erin was a relatively calm rehearsal for the hurricane season.
"It was a good dry run. I hope it stays dry," Corpus Christi Mayor Henry Garrett said after Erin had moved ashore as a tropical depression and largely spared the Gulf Coast city.
Houston-based Transocean Inc. said it was taking precautions to deal with the storms. The operator of the largest deepwater drilling rig fleet in U.S. waters in the Gulf of Mexico said it had evacuated 11 nonessential workers as a precaution. About 125 people remain on board the moored, semisubmersible rig about 160 miles southeast of New Orleans.
Shell Oil Co. evacuated 188 people this week from offshore facilities in Erin's path and said it was already monitoring Dean.
Hurricane specialists expect this year's Atlantic hurricane season — June 1 to Nov. 30 — to be busier than average, with as many as 16 tropical storms, nine of them strengthening into hurricanes. Ten tropical storms developed in the Atlantic last year, but only two made landfall in the United States.