Hurricane Wilma gathered strength at lightning speed today, turning into the most intense Atlantic storm ever recorded.

Forecasters had originally predicted that the Category 5 hurricane was headed toward Florida's west coast over the next few days, but late this afternoon said that computer models were shifting and it was extremely difficult to know for sure where the storm was headed.

"This is one of the more perplexing storms," Max Mayfield, director of the National Hurricane Center in Miami, said at a news conference late this afternoon as he detailed three forecasts that are being studied. "But the good news is that this buys us more time."

Mayfield said the three competing models show Wilma hitting Florida, racing up the Atlantic and crashing into New England; or hitting Florida this weekend but moving much slower up the Atlantic; or staying in the Caribbean and not reaching the Gulf of Mexico. He said forecasters had much lower confidence than usual because the storm continues to wobble and because the models cannot reach agreement on how far south a weather system currently over the western United States will extend when it reaches the Midwest. The position of that system would affect Wilma's course, he said.

Mayfield said the hurricane center will send a jet to the storm tomorrow to get more readings and that may help determine Wilma's course.

The latest advisory from the hurricane center in Miami called Wilma a "potentially catastrophic" hurricane, now located about 285 miles southeast of the Mexican beach resort of Cozumel.

In the 5 p.m. EDT advisory, the center said the hurricane had weakened slightly from the morning although it still remained a Category 5 storm.

The director of the center warned, however, that even if it weakens, Wilma remains a very dangerous hurricane and he said residents of southern Florida "can't let your guard down."

Officials in south Florida ordered tourists and people living on boats out of the Florida Keys, the first U.S. evacuations caused by the storm, according to Greg Artman, public information officer for Florida's Monroe County.

The hurricane center said Wilma set a record for hurricane intensity in the Atlantic, as the minimum atmospheric pressure of the monster storm dropped to 882 millibars. In the latest advisory, the hurricane center said atmospheric pressure had risen to 900 millibars. It said "an Air Force aircraft will be in the center of Wilma shortly to provide a direct measure of the central pressure."

The hurricane also set a record as the most rapidly strengthening hurricane on record.

"The bottom really did drop out during the night," Mayfield said in a briefing earlier in the day. "It went from a tropical storm to a Category 5 hurricane in a very short period of time."

Generally, the lower the pressure in the storm, the more intense the hurricane, as the low-pressure area becomes a giant vacuum device, sucking in ever-more heat and energy, the fuel of the storm. Lower pressure means higher wind speed.

Hurricane Katrina, which devastated the Gulf Coast, was measured at 902 millibars at its peak strength.

Wilma, which grew into a powerhouse Category 5 hurricane in less than 24 hours, is churning winds at nearly 165 mph with higher gusts, the hurricane center said.

Hurricane force winds extend outward from its eye up to 50 miles and tropical storm force winds extend out to 160 miles. Category 5 is the highest ranking on the Saffir-Simpson scale of hurricane intensity.

Forecasters issued a hurricane watch for Cuba and Mexico's Yucatan Peninsula. A tropical storm warning is in effect for Belize and Honduras. Mayfield predicted the hurricane will have "a big impact on the western portion of Cuba."

A hurricane warning means that hurricane conditions are expected. "Preparations to protect life and property should be rushed to completion," the center's advisory said.

The hurricane center said Wilma was moving slowly west-northwest at about 7 mph. During the next few days, the hurricane is expected to veer toward Florida's west coast, forecasters said.

Wilma is the 12th hurricane of the Atlantic Ocean season and the 21st named storm. Wilma exhausts this year's list of storm names, and any additional storms and hurricanes that form this season will be named using the Greek alphabet, starting with Alpha.

The hurricane season lasts until Nov. 30. Hurricane specialist Stacy Stewart from the hurricane center said the Atlantic Ocean is currently in an active 30-year hurricane period, which started in 1995. He said the recent stepped-up activity is not unusual for an active period.

Staff writer Lexie Verdon contributed to this story.