Here comes the melt; watch those hubcaps

A prodigious snow removal project will get underway in earnest this weekend, and neither the New Jersey nor the Pennsylvania Department of Transportation will have to lower a plow.

As if to prove itself worthy of the onset of daylight saving time - which arrives at 2 a.m. Sunday - the March sun will show off its might and go to town on the estimated 2.5 billion pounds of snow layered across the region.

Never mind that near-record low expected Saturday morning, around 15 degrees, or that temperatures still will be six to 12 degrees below normal during the day.

Given that PennDot's Philadelphia region has set a two-winter record for salt use, with more than 310,000 tons - more than 150,000 of that this season - one would think that an impending melt would warm the agency's collective heart.

Not quite.

"It's going to be tough for us," said PennDot spokesman Charles Metzger.

The combination of daytime melting and overnight freezing is right from the how-to-make potholes manual. A flying hubcap advisory might be in the offing.

"There's a doozy [pothole] on the 611 bridge in Willow Grove," Metzger said.

Assuming the forecasts hold and temperatures reach the mid-40s from Sunday through Tuesday and the mid-50s on Wednesday, road-patching crews soon will be spelling the snow fighters.

Potholes start with moisture seeping into soil below the road surface. When that moisture freezes, the ground expands, pushing up the pavement. When it warms up, the pavement remains raised, but the ground goes back to where it was. This creates a gap. When tires go over the surface, it crumbles into the hollow space, and a pothole is born.

As of Friday, the region had a copious supply of moisture for seepage, with locked-up snow and ice equal to an inch or so coating of water, according to the Middle Atlantic River Forecast Center in State College, Pa.

Based on the standard formula, the total weight of all that snow and ice would be just over 2.5 billion pounds.

Since Feb. 1, 18.6 inches of snow has been measured officially in Philadelphia, and temperatures have averaged about 10 degrees below normal, constituting one of the more severe late-winter sieges in records dating to 1874.

On the plus side, despite all that water locked in the snow pack here and in upstate Pennsylvania, the river center said an uneventful melt is likely. No significant precipitation is in the forecast for the next several days.

"Let it melt nice and slowly," said the center's Jason Nolan, "and we're in good shape."

Editor's Note: This story was revised to correct the first reference of the estimated weight of the snow that fell on the region. It is 2.5 billion pounds, not tons.

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