The weekend's relentless, paralyzing snowstorm ended about noon Saturday and entered the record books as the fourth worst in the region's history, but its effects will linger for some time.

With an official accumulation of 21.1 inches at Pittsburgh International Airport, but higher in some areas, the storm that pummeled the mid-Atlantic states for nearly 24 hours continued to bedevil the region overnight and into today as state, county and municipal emergency declarations remained in effect.

Many roads remained slick and dangerous, and about 130,000 customers in southwestern Pennsylvania remained without electricity after heavy, moisture-laden snow felled trees and limbs, snapping electrical wires.

That situation was exacerbated by an overnight low expected to dip to 7 degrees. Nowhere in the foreseeable future is the temperature expected to rise above freezing, meaning the nearly 2 feet of snow won't be melting anytime soon.

And it's supposed to snow again Tuesday into Wednesday -- but only a few inches or so.

The only upside of such a weather downer is that things could have been much worse given the storm's power, punch and potential danger.

The snowfall averaged nearly an inch an hour, according to the National Weather Service. The most intense periods were from 7 p.m. to midnight Friday, when 7 inches fell, and from 3 to 6 a.m. Saturday, when another 5.3 inches bombed the area. It was worse in areas of higher elevation -- Somerset County saw 30 inches of snow.

Weather service meteorologist Brad Rehak said that, from a scientific standpoint, the storm was one of the most interesting he had seen in his 21 years in the business.

"When you get over an inch an hour, it's a very heavy snow," Mr. Rehak said. "It's very unusual for that extended period of time. Usually you'll get a burst for only an hour or two."

He said forecasts had underestimated the snowfall by 7 inches or more because the storm tracked farther north than had been anticipated.

PennDOT District 11 spokesman Jim Struzzi said Saturday night that he expected roadways to be open and clear today, with the exception of those with downed power lines.

"Hopefully things will be quiet [Sunday]," he said.

In addition to clearing roads, county and municipal government officials responded by opening "warming centers" to shelter those without electricity and prioritizing emergency calls so that the most urgent were answered first.

"Generally we're pleased on how far we've progressed, but we've got a long way to go," said Bob Full, Allegheny County's emergency services chief. "We're very fortunate we have not had any attributable deaths or major injuries so far.

"This was forecast to be much less snow than we actually got, but we're satisfied with how the emergency management personnel at the local level have operated over the past 24 hours."

Still, it was a heck of a storm, bested by only three in the region's history since the National Weather Service began keeping records in 1884. The only accumulation in recent history that compares was the 25.3 inches that doused the area between March 12-14, 1993, known hereabouts as the St. Patrick's Day Parade Storm.

The most recent storm was unlike that event because the snow was full of moisture and heavy, which is why it caused more damage to trees and power lines. The 1993 storm was characterized by drier snow and heavy winds, which caused large drifts.

This storm shattered century-old records for Feb. 5 and 6. The previous record for Feb. 5 was 4.7 inches in 1899; Friday's snowfall was 11.4 inches. The previous Feb. 6 record was 4.3 inches in 1911, which was more than doubled by the 9.7 inches dumped by this storm.

Unlike the 1993 storm, the weekend snowfall shut down virtually everything Saturday. The Pittsburgh airport ceased flight operations until around 8 p.m. The Port Authority shut down most transit service and said it would assess the situation early this morning.

Among many cancellations and postponements was the Pittsburgh Fraternal Order of Police vote on a new contract with the City of Pittsburgh, which was rescheduled for Saturday. Roman Catholics in the Pittsburgh and Greensburg dioceses received dispensation from their obligation to attend Mass today. Businesses either didn't open or did little business.

But remarkably, some events went on as scheduled, such as the University of Pittsburgh's men's basketball game with Seton Hall at the Petersen Events Center in Oakland.

Authorities said widespread power outages persisted last night. Driving conditions continued to be dangerous, and many secondary roads remained impassable.

Power outages were compounded by road conditions, which slowed electric company crews from reaching some areas to restore service. Electrical companies could not estimate when all customers would have service restored.

Across the state, tens of thousands Allegheny Power customers remained without power Saturday night -- most of them in southwestern counties.By 10 p.m., Duquesne Light estimated that 26,000 customers in Allegheny and Beaver counties remained without service-- down from a high of 57,000 customers in the morning.

Duquesne Light spokesman Joseph H. Vallarian said there had been 1,100 cases of downed wires, 250 cases of downed trees or tree limbs on wires and 51 damaged poles.

In Fayette County, warming centers opened to help the 18,000 people who were without power. By 3 p.m. Saturday, the county 911 center had received more than 1,400 calls in less than 24 hours, most of them for fallen power lines and power outages that resulted.

But residents apparently listened when advised by officials to stay safe by staying put.

"We really don't have any accidents because people are taking heed to the fact that they can't get out," said Susan Griffith, spokeswoman for the county's Emergency Management Agency. "And nothing's open anyway."

Road crews in Westmoreland County struggled to dig out of snow that on average was 18 inches in the western part of the county and nearly 3 feet atop Laurel Ridge to the east, said Daniel Stevens, a county spokesman. Jackknifed tractor-trailer trucks also shut down traffic on the Pennsylvania Turnpike.

Snow cleared from roads had to be piled high against utility poles, he said. With evening approaching, those piles were complicating efforts by utility crews to get close enough to those poles to make repairs.

"There was a period of time [Saturday] morning when we had fire trucks, snow plow trucks, ambulances and everything else stuck," Mr. Stevens said of the road conditions. "It was bad."

At Pittsburgh International Airport, stranded travelers ended up in the terminal or at the airport Hyatt hotel. The airport fire department made rounds inside the terminal to see if travelers had medical or other needs, said JoAnn Jenny, spokeswoman for the county airport authority.

Earlier, officials hoped to have the ramps and runways operational by noon, but it became clear as the morning progressed that such a timetable was unrealistic given the rate of snow accumulation, she said.

Snow depth at the airport had already reached 19 inches by then, she said.

In Washington County, warming shelters were serving some of the 51,000 Allegheny Power customers without service as of mid-afternoon, said Jared Jenkins, shift supervisor with the county's 911 center.

"I'm trying to think of a nice way to say this," he said. "There are outages all over the place. It hasn't gotten any better. It's only gotten worse."

As in other counties, crews in Washington were dealing with both the impact of the snow's weight on power lines and the implications for those in the dark as nighttime temperatures were due to reach single digits by morning.

Mr. Jenkins asked that callers inquiring about power outages refrain from calling 911, so as not to overwhelm emergency dispatchers.

In North Strabane, The Meadows Racetrack & Casino closed at 5 p.m. Saturday due to storm and state of emergency. It planned to reopen at 9 a.m. today.

In Beaver County, the American Red Cross was dispatched to check on motorists stranded for hours on the eastbound Pennsylvania Turnpike after two tractor trailers crashed and spilled diesel fuel.

Emergency crews Saturday night were still at the scene of the 1:30 p.m. crash in North Sewickley, said Eric Brewer, crew chief with the Beaver County Emergency Services dispatch center.

One injury was reported, though the patient's condition was not available.

Roads in the county "are passable" but "we're telling people to stay off them and let road crews do their jobs."

Earlier Saturday, crews slogged over snow-caked roads to respond to two house fires -- one on Allola Drive in New Sewickley and another on Martin Road in Hanover. No injuries were reported.

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