Hours after the National Weather Service downgraded Sandy from a hurricane to a tropical storm, a Hurricane Hunter aircraft recorded sustained winds at 75 mph, which passes the threshold of a Category 1 hurricane.
Regardless of its official category, Sandy is expected to be a monstrous storm that poses a serious threat for the entire Eastern Seaboard.
Forecasters say Sandy is a massive cyclone, with hurricane-force winds recorded as far as 100 miles away from the eye of the storm.
Tropical storm conditions could be felt in the Carolinas by Saturday evening.
Tropical storm warnings were issued for parts of Florida's East Coast, along with parts of coastal North and South Carolina and the Bahamas. Tropical storm watches were issued for coastal Georgia and parts of South Carolina, along with parts of Florida and Bermuda.
In North Carolina's Outer Banks, light rain was falling Saturday and winds were building up to a predicted 30 to 50 mph. Gov. Beverly Purdue declared a state of emergency for some coastal areas, and a steady stream of campers and other vehicles hauling boats left the low-lying islands for the mainland. Residents feared a temporary bridge built after Irene last year poked a new inlet through the island could be washed out again, severing the only road off Hatteras Island.
Experts said the storm could be wider and stronger than Irene, which caused more than $15 billion in damage, and could rival the worst East Coast storm on record.
As it spun away from the Bahamas late Friday, Sandy was blamed for more than 43 deaths across the Caribbean. The 18th named storm of the Atlantic hurricane season hit the Bahamas after cutting across Cuba, where it tore roofs off homes and damaged fragile coffee and tomato crops.
Up and down the coast, people were cautioned to be prepared for days without electricity. Several governors, including Connecticut's Dannel Malloy and New Jersey's Chris Christie, declared states of emergency. And airlines said to expect cancellations and waived change fees for passengers who want to reschedule.
Mandatory evacuations were under way in southern New Jersey's barrier islands, which people were ordered to leave by Sunday afternoon, and Christie ordered the evacuations of all Atlantic City casinos and said state parks would close.
"We should not underestimate the impact of this storm and not assume the predictions will be wrong," Christie said during a storm briefing Saturday in North Midletown, near the coast. "We have to be prepared for the worst."
"Be forewarned," Malloy said. "Assume that you will be in the midst of flooding conditions, the likes of which you may not have seen at any of the major storms that have occurred over the last 30 years."
At a Home Depot in Freeport, on New York's Long Island, Bob Notheis bought sawhorses to put his furniture on inside his home.
"I'm just worried about how bad it's going to be with the tidal surge," he said. "Irene was kind of rough on me and I'm just trying to prepare."
After Irene left millions without power, utilities were taking no chances and were lining up extra crews and tree-trimmers. Wind threatened to topple power lines, and trees that still have leaves could be weighed down by snow and fall over if the weight becomes too much.
New York City began precautions for an ominous but still uncertain forecast. No decision had been made on whether any of the city's public transportation outlets would be shut, despite predictions that a sudden shift of the storm's path could cause a surge of 3 to 6 feet in the subways.
The subway system was completely shuttered during Irene, the first such shutdown ever for weather-related reasons. Irene largely missed the city, but struck other areas hard.
In upstate New York, Richard Ball was plucking carrots, potatoes, beets and other crops from the ground as quickly as possible Friday. Ball was still shaky from Irene, which scoured away soil, ruined crops and killed livestock.
Farmers were moving tractors and other equipment to high ground, and some families pondered moving furniture to upper stories in their homes.
"The fear we have a similar recipe to Irene has really intensified anxieties in town," Ball said.
Sandy was projected to hit the Atlantic Coast early Tuesday. As it turns back to the north and northwest and merges with colder air from a winter system, West Virginia and further west into eastern Ohio and southern Pennsylvania are expected to get snow. Forecasters were looking at the Delaware shore as the spot the storm will turn inland, bringing 10 inches of rain and extreme storm surges, said Louis Uccellini, environmental prediction director for the National Oceanic and Atmospheric Administration.
Up to 2 feet of snow was predicted to fall on West Virginia, with lighter snow in parts of Ohio and Pennsylvania.
Jeff Masters, meteorology director of the forecasting service Weather Underground, said this could be as big, perhaps bigger, than the worst East Coast storm on record, a 1938 New England hurricane that is sometimes known as the Long Island Express, which killed nearly 800 people.
The storm loomed a little more than a week before Election Day, while several states were heavily involved in campaigning, canvassing and get-out-the-vote efforts. Republican presidential nominee Mitt Romney and Vice President Joe Biden both canceled weekend campaign events in coastal Virginia Beach, Va., though their events in other parts of the states were going on as planned. In Rhode Island, politicians asked supporters to take down yard signs for fear they might turn into projectiles in the storm.
The Associated Press contributed to this report.