SAN PEDRO SULA, Honduras -- The fringes of Hurricane Wilma lashed Caribbean nations yesterday, forcing schools to close and thousands to evacuate as it churned toward Mexico's Cancun resort and Florida after killing at least 12 people and becoming the most intense storm ever to form in the Atlantic.
The National Hurricane Center in Miami warned that Wilma would be a ''significant threat" to Florida by the weekend in a season that has already seen devastation from Hurricanes Katrina and Rita. Officials ordered tourists out of the Florida Keys.
''We had well over 1,000 lives lost in Katrina. If Wilma, you know, comes into the US, to the Florida coast as a Category 3 or 4 hurricane, that potential for large loss of life is with us," said hurricane center director Max Mayfield.
The White House, stung by criticism that it had not responded quickly enough to Katrina, promised to stay on top of the situation. ''We are closely monitoring what is an extremely dangerous storm," said White House spokesman Scott McClellan. ''People should take this hurricane very seriously."
Tourists packed Cancun's airport in hopes of catching flights out and MTV postponed its Video Music Awards Latin America ceremony, originally scheduled for today at a seaside park south of the resort town.
Floridians braced for the storm by boarding up windows and stocking up on supplies, although forecasters at the hurricane center said the forward motion of the Category 5 storm appeared to be slowing, which could cause it to eventually weaken.
Mayfield said Wilma may not reach the Florida Keys until Saturday, possibly toward the evening. It had earlier been expected to reach the Florida mainland Saturday. It was still a Category 5 storm with 160 mph winds, down from 175 mph earlier in the day.
Heavy rain from Wilma's outer bands also forced evacuations in Honduras, Cuba, Jamaica, and Haiti -- even as much of Central America and southern Mexico was still recovering from Hurricane Stan, which left more than 1,500 people dead or missing.
Wilma was on a curving course that would carry it through the narrow channel between Cuba and Mexico on Friday, possibly within a few miles of Cancun and Cozumel.
Wilma's confirmed pressure readings early yesterday dropped to 882 millibars, the lowest minimum pressure ever measured in a hurricane in the Americas, but it later lost power and rose to 900 millibars, according to the hurricane center. Lower pressure translates into higher wind speed.
The strongest Atlantic storm on record, based on pressure readings, had been Hurricane Gilbert in 1988, which registered 888 millibars.
With heavy rain, high winds, and rough seas already pounding coastal areas, flood-prone Honduras warned that Wilma posed ''an imminent threat to life and property." The country closed two Caribbean ports.
The head of Haiti's civil protection agency, Maria Alta Jean-Baptiste, said rains associated with Wilma caused floods and landslides that killed at least 11 people since Monday
Wilma is the record-tying 12th hurricane of the Atlantic season, the same number reached in 1969. Records have been kept since 1851. On Monday, Wilma became the Atlantic hurricane season's 21st named storm, tying the record set in 1933 and exhausting the list of names for this year.
The six-month hurricane season ends Nov. 30. Any new storms would be named with letters from the Greek alphabet, starting with Alpha.