Forecasters say they expect Irene to further strengthen over the next 24 hours.
Irene "got very well organized as she passed farther away from the big island of Hispaniola," says Bill Read, who heads the National Oceanic and Atmospheric Administration's National Hurricane Center in Miami.
Looking ahead to its effects on the US East Coast, the storm "will be a very large circulation as it moves north of the Carolinas" on Saturday, Dr. Read explained during a briefing on Wednesday. "The effects of the hurricane in the form of tropical-storm, maybe even hurricane-force winds, rain, beach erosion, and tidal surge will be in play from the mid-Atlantic all the way up through New England as the storm progresses."
At 11 a.m. EDT, Irene packed maximum sustained winds of 115 miles an hour with gusts to 130 miles an hour. Hurricane-force winds extended as far as 50 miles from the storm's eye, while tropical-storm force winds – between 33 and 73 miles an hour – extended as far as 205 miles from the storm's center.
Overnight, forecasters continued to nudge Irene's weekend track eastward.
The storm's center currently is projected to deliver a glancing blow Saturday to North Carolina's Outer Banks, with tropical-storm-force winds arriving as early as Saturday morning.
From there, Irene is currently projected to drive northeastward close to the coast but over open water. It is projected to cross the eastern tip of Long Island and make landfall near the Connecticut-Rhode Island border overnight Sunday to Monday. The track forecast then sends Irene spiraling up eastern Massachusetts and into central Maine Monday, where it is expected to retain its hurricane status.
Forecasters caution, however, that track forecasts so far in advanced of landfall can be as much as 250 miles off. Likewise, intensity projections can be off by as much as 23 miles an hour per additional day in advance of a storm's arrival.
But they add that the sheer size of the expanding storm suggests that heavy rain and high winds, in addition to dangerous surf and tide conditions along the coast, will affect areas far removed from the storm center's track.
Already, North Carolina officials have ordered evacuations for the Outer Banks, a major draw for vacationers in the summer. There, storm surge and the powerful waves that ride atop the surge from a passing Irene is the major concern.
The Federal Emergency Management Agency is using Ft. Bragg as a staging ground for supplies of tarps, generators, potable water, food, even baby formula. The supplies there will be available as needs arise up and down the mid-Atlantic region, says Craig Fugate, who heads FEMA.
In addition, concerns center on flooding.
The National Hurricane Center's Read notes that recent storms have dumped from five to 10 inches of rain along the mid-Atlantic region, with New England picking up from around one to five inches.
Read cautions that winds and torrential rains from Irene could topple trees clinging to soils already weakened by rainfall from previous storms, snapping power lines or damaging structures as they fall.
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