Tropical Storm Fay may reach hurricane strength, cross western Cuba early this morning and hit Florida later today, U.S. weather officials said.

The system, with maximum sustained winds of about 50 miles (80 kilometers) per hour, was about 235 miles south-southeast of Key West, Florida, and 170 miles southeast of Havana at 11 p.m. Miami time yesterday, according to the U.S. National Hurricane Center`s Web site. Fay, which left four people dead in Haiti and the Dominican Republic, may cause severe flash floods and mudslides in Cuba before reaching Florida.

A hurricane watch was issued by the center for the Florida Keys, a 150-mile chain of islands stretching from the state`s southern tip, as well as along the west coast of the mainland to Tarpon Springs, about 30 miles north of Tampa. Isolated tornadoes may occur in the Keys and the southern Florida peninsula, the center said.

``If people are calling, we`re telling them there is a mandatory evacuation,`` Joyce Smatts, general manager of the Pier House Resort in Key West, said in a telephone interview. The waterside hotel and conference complex is at the foot of Duval Street, the city`s main tourist thoroughfare. ``We had a lot of checkouts,`` she said.

The National Hurricane Center said Monroe County, which includes Key West, began evacuating visitors from the Keys from 8 a.m. yesterday.

Airport to Close

Key West International Airport will close at about midmorning today, its manager, Peter Horton, said. The airport handles 30 inbound and 30 outbound flights daily, down from a peak of 100 per day during the winter season, he said.

Cruise ships operating out of the Port of Miami were docked on Aug. 16 for passenger disembarkation. The ships normally leave on Sundays for destinations in the Caribbean and Gulf of Mexico. Royal Caribbean Cruises Ltd. and Carnival Corp. haven`t changed cruise schedules, officials said.

Transocean Inc., the world`s largest offshore oil driller, evacuated 130 workers at four rigs in the Gulf of Mexico as a precaution, Guy Cantwell, a spokesman for the Houston-based company, said in a telephone interview yesterday.

Royal Dutch Shell Plc, which evacuated about 160 offshore workers on Aug. 16, said yesterday it plans to evacuate about 200 people from its oil and natural-gas platforms in the eastern Gulf of Mexico because of Fay.

The company, Europe`s largest oil company by market value, hasn`t reduced production, it said in an e-mailed statement.

Operating as Normal

``I have not been notified of any evacuations yet,`` said Danny Holder, director of helicopter operator Air Logistics Inc. in New Iberia, Louisiana, in a telephone interview. ``It will depend if it takes a northerly turn here the next few hours.``

Air Logistics is a unit of Bristow Group Inc., the second- biggest helicopter operator in the Gulf.

ConocoPhillips spokesman Rich Johnson said in an e-mailed statement that there hadn`t been any effect on its operations because of the storm.

In Cuba, the government issued a hurricane watch from the provinces of La Habana and Ciudad La Habana to Sancti Spiritus, as the storm is forecast to cross western central Cuba early this morning, the center said.

Fay is moving to the northwest at about 10 mph and is forecast to turn north during the next two days, the U.S. hurricane center said. The storm may produce as much as 12 inches of rain in parts of Cuba and 10 inches for the Florida Keys and south Florida.

One man died Aug. 16 in Haiti while trying to cross a river in Leogane, south of the capital of Port-au-Prince, the Associated Press reported, citing the head of the country`s civil protection department.

A 34-year-old woman and her niece and nephew drowned while trying to cross a rain-swollen river in a car in the Dominican Republic, AP said, citing civil defense agency director Luis Luna Paulino.

Tropical storms have winds of at least 39 mph. A hurricane has minimum sustained winds of 74 mph.