The National Weather Service has posted a high wind warning and flood watch for Western Pennsylvania, including Pittsburgh.
The flood watch is in effect from Monday morning through Tuesday evening. The high wind warning runs from Monday afternoon to Tuesday evening. The weather service is forecasting sustained winds of 25 to 35 mph during that time, with gusts of up to 60 mph possible.
The warnings are triggered by the expected convergence of Hurricane Sandy with a stalled cold front. Rain is expected to continue well into the week, with several inches possible.
While Pittsburgh is unlikely to get more than a few flakes of snow mixed in with the heavy rain, AccuWeather is reporting that plowable snowfalls are possible Monday night and Tuesday from the Laurel Highlands southward over West Virginia into western Virginia.
Higher ridges of West Virginia, above 2,500 feet of elevation, could see falls of 1 to 2 feet by Wednesday. Travel on Interstates 64, 68, 77 and 81 may become difficult. Some counties in West Virginia and Maryland are under a blizzard warning.
In briefing material released today, the weather service said the heaviest rain and strongest wind in Western Pennsylvania will occur Monday night and through the day Tuesday.
Creeks, streams and poor-drainage areas are likely to flood, and river flooding is possible later in the week.
The Edison Electric Institute, an association of U.S. power companies, said utilities in the Northeast are bringing in crews and equipment from as far away as New Mexico, Texas and Oklahoma in anticipation of widespread service disruptions from what is increasingly appearing to be a storm of unprecedented size and strength.
"We strongly urge customers to prepare for the possibility of extended outages due to the enormity of Hurricane Sandy, which forecasters predict may become the worst storm to hit the Northeast in 100 years," said Brian Wolff, institute senior vice president.
"Member companies have been pre-mobilizing thousands of storm and field personnel, calling on extra workers and resources from across the country in anticipation of this extended, slow-moving major weather event that is expected to devastate the electric system for days," he said.
Across the Northeast, the yet-to-arrive storm already was tossing around everything from school schedules to air and ground transportation.
President Barack Obama was monitoring the storm and working with state and local governments to make sure they get the resources needed to prepare, administration officials said.
Governors in several states, including Pennsylvania, have declared states of emergency.
Philadelphia city schools are closed Monday and the city's public transit system was to shut down shortly after midnight.
In New York City, the subway system was to shut down at 7 p.m. and buses at 9 p.m. today, and Mayor Michael Bloomberg ordered about 375,000 people living in low-lying areas to evacuate by this evening.
And more than 5,000 flights scheduled for Sunday and Monday were scrubbed.
Megabus.com has announced several route cancelations today through Tuesday, including the New York/State College/Pittsburgh runs on Monday. The company said customers booked on these routes will receive an email with further information.
Residents in several states have been warned to prepare for several days of lost power.
Sandy weakened briefly to a tropical storm Saturday but was soon back up to Category 1 strength, packing 75 mph winds. It was about 275 miles south-southeast of Cape Hatteras, N.C., and moving northeast at 14 mph as of 2 a.m. Sunday. Forecasters said the storm was spreading tropical storm conditions across the coastline of North Carolina, and they were expected to move up the mid-Atlantic coastline late Sunday.
Experts said the storm was most likely to hit the southern New Jersey coastline by late Monday or early Tuesday.
Delaware ordered mandatory evacuations for coastal communities by 8 p.m. Sunday.
The storm forced the presidential campaign to juggle schedules. Former Gov. Mitt Romney scrapped plans to campaign Sunday in the swing state of Virginia and switched his schedule for the day to Ohio. First lady Michelle Obama canceled an appearance in New Hampshire for Tuesday, and Mr. Obama moved a planned Monday departure for Florida to Sunday night to beat the storm. He canceled appearances in Northern Virginia on Monday and Colorado on Tuesday.
What makes the storm so dangerous and unusual is that it is coming at the tail end of hurricane season and the beginning of winter storm season, "so it's kind of taking something from both," said Jeff Masters, director of the private service Weather Underground.
Mr. Masters said the storm could be bigger than the worst East Coast storm on record -- the 1938 New England hurricane known as the Long Island Express, which killed nearly 800 people.
The storm is so big, and the convergence of the three storms so rare, that "we just can't pinpoint who is going to get the worst of it," said Rick Knabb, director of the National Hurricane Center in Miami.
New York Gov. Andrew Cuomo announced plans this morning to shut down the subways in New York City. The city closed the subways before last year's Hurricane Irene, and a Columbia University study predicted that an Irene surge just 1 foot higher would have paralyzed lower Manhattan.
On Saturday evening, Amtrak began canceling train service to parts of the East Coast, including between Washington, D.C., and New York. Airlines started moving planes out of East Coast airports to avoid damage and adding flights out of New York and Washington on Sunday in preparation for flight cancellations on Monday.
Utility officials warned rains could saturate the ground, causing trees to topple into power lines, and told residents to prepare for several days at home without power. "We're facing a very real possibility of widespread, prolonged power outages," said Ruth Miller, spokeswoman for the Pennsylvania Emergency Management Agency.
The Associated Press contributed. Jon Schmitz: email@example.com or at 412-263-1868. First Published October 28, 2012 1:00 PM