The weather monster that U.S. forecasters call "Frankenstorm" was looking more ominous by the hour for the East Coast on Friday.

Meteorologists expect a natural horror show of high wind, heavy rain, extreme tides and maybe snow for several days beginning early Sunday, peaking with the arrival of Hurricane Sandy on Tuesday.

"It's looking like a very serious storm that could be historic," said Jeff Masters, meteorology director of the forecasting service Weather Underground.

With a rare mix of three big merging weather systems over a densely populated region, experts predict at least $1 billion in damage.

Hurricane Sandy, having blown through Haiti and Cuba and leaving at least 40 dead across the Caribbean, continues to barrel north as the lowest category hurricane. A wintry storm is moving across the U.S. from the west. And frigid air is streaming south from Canada.

If they meet Tuesday morning around New York or New Jersey, as forecasters predict, they could create a big, wet mess that settles over the nation's most heavily populated corridor and reaches as far west as Ohio.

Government forecasters said there is a 90 percent chance _ up from 60 percent two days earlier _ that the East Coast will get pounded.

The National Oceanic and Atmospheric Administration said Friday that wherever the storm comes ashore, there will be 10 inches (254 millimeters) of rain and extreme storm surges. Up to 2 feet (0.6 meters) of snow should fall on West Virginia, with lighter snow in parts of Ohio and Pennsylvania.

"It's going to be a long-lasting event, two to three days of impact for a lot of people," said James Franklin, forecast chief for the National Hurricane Center.

Some have compared the tempest to the so-called Perfect Storm that struck off the coast of New England in 1991, but that one hit a less populated area.

"The Perfect Storm only did $200 million of damage and I'm thinking a billion" this time, Masters said. "Yeah, it will be worse."

On Friday afternoon, the hurricane's center was about 30 miles (50 kilometers) north-northeast of Great Abaco Island in the Bahamas and 430 miles (695 kilometers) south-southeast of Charleston, South Carolina. Sandy was moving north at 7 mph (11 kph) with maximum sustained winds near 75 mph (120 kph).

___

Associated Press writers Tony Winton in Miami, Fernando Gonzalez in Cuba, Ken Thomas on Air Force One, Michael Rubinkam in Harrisburg, Pennsylvania, and Karen Matthews in New York contributed to this report.

___

Seth Borenstein can be followed at http://twitter.com/borenbears