A new tropical storm has formed in the Caribbean -- matching a 72-year-old record for the highest number of Atlantic storms in a single season.

Tropical Storm Wilma is the 21st named storm of the 2005 season and is expected to become a hurricane before heading to Mexico's Yucatan peninsula and possibly the battered U.S. Gulf coast by the end of the week.

The last time this many storms formed since record-keeping began 154 years ago was in 1933.

If Wilma does turn into the season's 12th hurricane it would also tie a 1969 record of the most hurricanes in one term.

"I think the message is that the season is certainly not over. People in the Gulf Coast are going to have to watch Wilma," National Hurricane Center director Max Mayfield told The Associated Press on Monday.

At 8 p.m. ET Monday, Wilma had sustained winds nearing 85 km/h and was centered about 425 km southeast of Grand Cayman, according to the Hurricane Center.

Forecasters expect the storm to bring 4 to 6 inches of rain to the Cayman Islands and Jamaica, with as much as 12 inches possible in some areas.

Reeling from the devastating effects of Katrina, Rita, and Dennis, the residents of the Gulf Coast are hoping Wilma stays away.

"There's no scenario now that takes it toward Louisiana or Mississipppi, but that could change," Mayfield said.

Hurricane Katrina, which hit on August 29, killed more than 1,240 people and is expected to cause more than $34 billion in insured losses.

Since 1995, the Atlantic has been in a period of higher hurricane activity. Scientists say the cause of the increase is a rise in ocean temperatures and a decrease in the amount of disruptive vertical wind shear that rips hurricanes apart.

Some researchers argue that global warming fueled by man's generation of greenhouse gases is the culprit.

Forecasters at the National Hurricane Center say the busy seasons are part of a natural cycle that can last for at least 20 years, and sometimes up to 40 or 50. They say the conditions are similar to those when the Atlantic was last in a period of high activity in the 1950s and 60s.

It's also difficult to know whether the Atlantic was even busier at any time before record keeping began in 1851. And satellites have only been tracking tropical weather since the 1960s, so some storms that just stayed at sea before then could have escaped notice.

The six-month hurricane season ends November 30.