The weather monster that forecasters call 'Frankenstorm' is looking more ominous by the hour for the US East Coast.
Meteorologists expect high wind, heavy rain, extreme tides and maybe snow beginning early tomorrow, peaking with the arrival of Hurricane Sandy on Tuesday.
"It's looking like a very serious storm that could be historic," said Jeff Masters, of the forecasting service Weather Underground.
With a rare mix of three big weather systems over a densely populated region, experts predict at least $1bn in damage.
Hurricane Sandy, having blown through Haiti and Cuba and leaving nearly 30 dead, continues to barrel north as the lowest category hurricane. A wintry storm is moving across the US from the west. And frigid air is streaming south.
If they meet on Tuesday morning around New York, as forecasters predict, they could create a big, wet mess that settles over the nation's most heavily populated corridor.
Government forecasters said there is a 90pc chance -- up from 60pc two days ago -- that the East Coast will get pounded.
"What we are doing is 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.
Some have compared the tempest to the so-called Perfect Storm that struck off the coast of New England in 1991.
"The Perfect Storm only did $200m of damage and I'm thinking a billion" this time, Masters said. "Yeah, it will be worse."
Yesterday morning, Hurricane Sandy's centre was about 25 miles north-northeast of Great Abaco Island in the Bahamas and 460 miles south-southeast of Charleston, South Carolina. It was moving north at 6mph, with maximum sustained winds near 80mph.
Sandy left 29 people dead across the Caribbean. The hurricane, which weakened to a category 1 last night, caused havoc in Cuba, killing 11 people as its howling winds and rain toppled houses and ripped off roofs.
Authorities said it was Cuba's deadliest storm since July 2005, when Hurricane Dennis killed 16 people and caused $2.4bn (¤1.8bn) in damage.
Sandy also killed one person while battering Jamaica on Wednesday and 16 in Haiti, where heavy rains from the storm's outer bands caused flooding in the impoverished and deforested country.
Police in the Bahamas said a 66-year-old man died after falling from his roof late yesterday while trying to repair a window shutter. Government officials said the storm seemed to have inflicted the greatest damage on Exuma, where there were reports of downed trees, power lines and damage to homes.
A new tropical storm watch was issued early yesterday for a section of the US East Coast extending from Savannah, Georgia, northward to North Carolina's Outer Banks.