MIAMI - The first tropical storm of the 2006 Atlantic hurricane season, Alberto, formed off Cuba on Sunday and appeared headed toward Florida, the US National Hurricane Centre said.
The storm, located during late afternoon near latitude 24.5 north and longitude 87.8 west in the Gulf of Mexico, was about 605km west of Key West, Florida, according to the centre's website.
Alberto was a wake-up call for a new hurricane season for US coastal residents battered by eight hurricanes in the last two years, including Hurricane Katrina - the most costly and one of the deadliest natural disasters in America's history.
Alberto's maximum sustained winds rose to nearly 75km/h, but the winds, which reached as far as 370km east of the storm's centre, were expected to change little during the next day, the forecasters in Miami said.
Forecasters described Alberto as "disorganised" and said the storm, which was headed northwest at 11km/h, would turn gradually toward the northeast during the next 24 hours.
Alberto has dumped heavy rain on Cuba and was predicted to make landfall in heavily populated Florida on Tuesday, cross the northern part of the state, and then enter the Atlantic.
The US hurricane forecasters issued a warning for Florida's west coast from Bonita Beach to Steinhatchee, cautioning residents that tropical storm conditions were possible during the next 36 hours.
"Rainfall totals of 125 millimetres to 250 millimetres are possible over the Florida Keys and the Florida peninsula through Tuesday," the hurricane centre said in a late-afternoon bulletin.
Florida emergency management officials have put responders on heightened alert by activating the state's emergency operations center to monitor the storm.
Civil defence officials in Cuba reported Alberto had forced 26,000 people to evacuate low-lying areas in the Caribbean island's western-most province of Pinar del Rio, where 400mm to 500mm of rain fell in 24 hours.
Some minor flooding was seen but no deaths, injuries or significant damage to housing or agriculture were reported, according to the Cuban officials.
Tropical storms, while they do not present a significant threat to developed nations, can cause deadly floods in low-lying areas and destroy ramshackle buildings.