(CNN) -- Rainstorms spun off by Tropical Storm Erin hit the Texas coast Wednesday evening as the storm churned through the Gulf.
Satellite imagery shows Tropical Storm Erin intensifying Wednesday evening in the Gulf of Mexico.
The Texas National Guard deployed water rescue teams along the coast to prepare for Erin's landfall, expected Thursday morning north of Corpus Christi, Texas.
Erin, with 40 mph winds, is not expected to achieve hurricane strength before reaching the shore, but up to 8 inches of rain and a storm surge of up to 3 feet are forecast for coastal areas of Texas.
As of 10 p.m. in Texas (11 p.m. ET), the center of Erin was about 140 miles southeast of Corpus Christi and 200 miles south-southwest of Galveston. A tropical storm warning was in effect for most of the state's coast, from Brownsville to San Luis Pass, near Galveston. See where the storm appears to be headed »
A tropical storm warning means tropical storm conditions, including winds of at least 39 mph, are expected within 24 hours.
Authorities in Mexico dropped an earlier tropical storm watch for its northeast coast.
Texas Gov. Rick Perry urged state residents to take "all possible precautions to stay out of dangerous situations." Watch why some Texans say they aren't worried »
"Because storms have saturated much of our state this summer, many communities in this storm's projected path are at high risk of dangerous flash flooding," Perry said in a written statement.
Three helicopters are being readied in San Antonio, the statement said, each with a two-person water rescue team, and six other swift-water rescue teams will be on standby.
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Meanwhile, Tropical Storm Dean intensified as it moved toward the Leeward Islands in the Atlantic. It was expected to become a hurricane by the time it reached them Friday, the National Hurricane Center in Miami said.
The latest long-range forecast had the storm reaching Category 4 status -- with winds of at least 131 mph -- by Monday in the western Caribbean between Cuba and Mexico's Yucatan peninsula.
The latest forecasts don't show Dean as a threat to the United States, although it could reach the Gulf of Mexico early next week. No hurricane has made landfall in the mainland United States since Wilma struck Florida in late October 2005.
The storm's most immediate threat is to the Lesser Antilles, where people were urged to monitor the storm's progress. The National Hurricane Center said a hurricane watch could be posted for the islands late Wednesday or early Thursday. A watch means hurricane conditions, including sustained winds of at least 74 mph, are expected within 36 hours.
At 11 p.m. Wednesday, the center of Dean was about 625 miles east of Barbados, moving west at about 23 mph. The storm's maximum sustained winds were about 70 mph, and forecasters said it could reach the 74 mph threshold needed to become a hurricane either Wednesday night or Thursday morning.
Dean is forecast to cross the Lesser Antilles Friday, then strengthen as it moves westward across the Caribbean to the south of Puerto Rico, the Dominican Republic, Haiti and Cuba. On that track, both Jamaica and the Cayman Islands would be directly in line for a major hurricane.
However, because the movement of a hurricane can be unpredictable, the actual path a storm takes often varies from the long-range forecast. Almost the entire Caribbean -- the Bahamas to Venezuela -- could be affected by Dean, according to the hurricane center.
Hawaii avoided a potential hurricane overnight as Flossie weakened to a tropical storm Wednesday. It left the area after buffeting the state's Big Island with strong winds and heavy rains.
The storm is expected to weaken further over the next 24 hours.
CNN meteorologist Reynolds Wolf, reporting from Hawaii, said Wednesday the winds there had died down considerably in the past few hours and rainfall was only sporadic.
A tropical storm warning remains in effect for Hawaii, but conditions will continue to improve throughout the day, Wolf said.
