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NEW YORK (AP) — Hurricane Sandy is gaining strength and has taken a left turn toward the East Coast and its date with two other weather systems. An official with the National Oceanic and Atmospheric Administration is calling it "the worst-case scenario."

The storm, with tropical storm-force winds extending almost 500 miles from its center, is expected to blow ashore along the New Jersey coast tonight or early tomorrow. Combined with high tides and a full moon, it brings the fear of a huge surge of seawater.

The combined storm is expected to affect everyone from the East Coast to the Great Lakes, with up to 3 feet of snow forecast for the West Virginia mountains.

Airlines have canceled thousands of flights in the Northeast and air travel could come to a halt for at least two days. That has caused a ripple effect across the globe.