WASHINGTON – Tourists flocked to the monuments in the nation’s capital Sunday to enjoy 50-degree temperatures before yet another winter storm was expected to dump up to a foot of snow on parts of the East Coast.

In the latest blast of a harsh winter, forecasters said a layer of ice and 8 to 12 inches of snow were possible by the end of Monday in Washington and the Mid-Atlantic region, while 6 to 8 inches of snow were predicted across parts of southern Pennsylvania. Nearly a foot of snow was expected in parts of New Jersey.

“I’m over it,” said Yasmon Hanks, 24, of Hampton, Va., echoing thoughts of many who’ve been cooped up inside this winter.

Hanks visited the Martin Luther King Jr. Memorial on the National Mall with her husband, Lynwood, and two young children. She was happy to be able to get outside, she said, because “I thought it was going to be way worse.”

Elsewhere on the Mall, joggers were out in shorts and T-shirts, families flew kites and tour guides led groups around landmarks such as the Washington Monument and Lincoln Memorial. Cherry blossom trees were growing new buds for the spring.

But, oh how so much can change in a matter of hours.

More snow and ice, perhaps as much as 2 inches falling every hour, were on the way ahead of Monday’s morning commute. By late Sunday afternoon, rain had moved into the Washington area, temperatures dropped and the city had declared a snow emergency beginning early Monday.

A round of wintry precipitation moved across much of the nation Sunday, bringing a mix of freezing rain and heavy snow to central and eastern states. Authorities warned of possible power outages and flight disruptions from weather that could affect millions.

In Pittsburgh, snow began falling about dawn and was expected to taper off before another band of snow hits early Monday. Forecasters were expecting 3 to 6 inches total.

Philadelphia was expected to get 4 to 8 inches through Monday. More than 6 inches would make it the city’s second snowiest winter, surpassing 65.5 inches that fell in 1995-96.

Nearly 1,600 flights in the United States were canceled and another 1,515 delayed Sunday afternoon, according to flight tracking site FlightAware.com. The bulk of the problems were in Dallas, Chicago and Newark, N.J. Another 1,115 flights for Monday were also already canceled. There are more than 30,000 U.S. flights on a typical day.

The same weather system inundated California with rain. Four hikers were rescued overnight after they became trapped by rising floodwaters in Malibu Creek State Park.