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 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.

If they meet on 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.

“What we are doing is we are taking the kind of precautions you should expect us to do, and I don’t think anyone should panic,” New York Mayor Michael Bloomberg said Thursday.

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.”

More In: International | News