Irene a storm no more, but flooding a danger

David Lutz of Red Hook wades through water over two feet deep as he enters the Brooklyn Cruise Terminal in the aftermath of Hurricane Irene on August 28, 2011 in the Brooklyn borough of New York City. The hurricane hit New York as a Category 1 storm before being downgraded to a tropical storm. Getty Images/Jemal Countess

Updated 11:07 p.m. EST

NEW YORK - Stripped of hurricane rank earlier Sunday, Irene has now been downgraded from Tropical storm strength as well. The storm spent the last of its fury Sunday, leaving treacherous flooding and millions without power -- but an unfazed New York and relief that it was nothing like the nightmare authorities feared.

Storm warnings for the East Coast were lifted late Sunday night, although the system was still capable of producing winds greater than 50 mph. It is officially categorized as a post-tropical cyclone now.

Slowly, the East Coast surveyed the damage, up to $7 billion by one private estimate, and worried of danger still lurking: the possibility of rivers and streams swelling with rainwater and overflowing over the next few days.

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"This is not over," President Barack Obama said from the Rose Garden.

Meanwhile, the nation's most populous region looked to a new week and the arduous process of getting back to normal.

New York lifted its evacuation order for 370,000 people and said it hoped to have its subway, shut down for the first time by a natural disaster, rolling again Monday, though maybe not in time for the morning commute. Philadelphia restarted its trains and buses.

Nearly all the East Coast airports shut down by the storm expect full service to be restored by noon on Monday. Amtrak said Sunday it is working to end cancellations on many of its East Coast lines.

"All in all," New York Mayor Michael Bloomberg said, "we are in pretty good shape."

At least 21 people died in the storm, most of them when trees crashed through roofs or onto cars.

The main New York power company, Consolidated Edison, didn't have to go through with a plan to cut electricity to lower Manhattan to protect its equipment. Engineers had worried that salty seawater would damage the wiring.

And two pillars of the neighborhood came through the storm just fine: The New York Stock Exchange said it would be open for business on Monday, and the Sept. 11 memorial at the World Trade Center site didn't lose a single tree.

The center of Irene passed over Central Park at midmorning with the storm packing 65 mph winds. By evening, with its giant figure-six shape brushing over New England and drifting east, it was down to 50 mph. It was expected to drift into Canada later Sunday or early Monday.

"Just another storm," said Scott Beller, who was at a Lowe's hardware store in the Long Island hamlet of Centereach, looking for a generator because his power was out.

But in the low-lying community of Long Beach, Long Island, Irene arrived at the worst possible time -- high tide. That led to several feet of flooding in some areas, though the waters quickly receded after Irene moved past, reports CBS News correspondent Elaine Quijano.

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The Northeast was spared the urban nightmare some had worried about -- crippled infrastructure, stranded people and windows blown out of skyscrapers. Early assessments showed "it wasn't as bad as we thought it would be," New Jersey Gov. Chris Christie said.

For most of the morning, coastal Connecticut fell under several feet of water, as high winds dropped hundreds of trees and an unknown number of power lines. But high tide was the worst of it. The storm surge disappeared as the tide receded, reports CBS News correspondent Wyatt Andrews.

Later in the day, the extent of the damage became clearer. Twenty homes on Long Island Sound in Connecticut were destroyed by churning surf.

The torrential rain chased hundreds of people in upstate New York from their homes and washed out 137 miles of the state's main highway.

Rivers roared in New Jersey and Pennsylvania. And in Rhode Island, which has a geography thick with bays, inlets and shoreline, authorities were worried about coastal flooding at evening high tide.

In Scotch Plains, N.J., flood waters nearly swallowed cars, according to CBS News correspondent Bigad Shaban.

The entire Northeast has been drenched this summer with what has seemed like relentless rain, saturating the ground and raising the risk of flooding, even after the storm passes altogether.