We survived region’s first snow

No one is calling it the "Blizzard of '07," but the Philadelphia region is experiencing its first prolonged snowfall of the year, and evidently is surviving the experience.

There have been no deaths, no injuries, no reported trauma and - officially, at least - no accumulation in Philadelphia.

Flakes that filtered into the area in late morning built to a slow but steady fall by afternoon. Totals ranged from 1.3 inches at by evening at Philadelphia International Airport, to afternoon measures of a half-inch in Center City, an inch in Exton, Chester County, and 1.4 inches in Wilmington.

Not only were the totals paltry, fears that the snow would be timed perfectly to exploit its modest disruptive potential for rush hour have turned out to be unfounded.

Roads remained merely wet in daytime, thanks to the faint sun behind the clouds. After sunset, hefty doses of salt have helped prevent a traffic nightmare.

"Traffic seems to be moving well," said Eugene Blaum, spokesman for the Pennsylvania Department of Transportation. PennDot had 350 trucks at the ready, and the New Jersey Department of Transportation dispatched 80 trucks to salt highways in the Garden State.

SEPTA reported no major problems.

The flakes were the product of a "clipper" storm that moved rapidly from the far Northern Plains to the Atlantic Coast. Such storms often dry out by the time they arrive here, but this one had a bit more juice than most.

It wasn't much, but if various weather experts are right, it may have been a preview of the winter, which begins officially just after midnight on Dec. 22.

They hold that the winter will be characterized by "nuisance" storms rather than those paralyzing nor'easters.

A moderate to strong La Nina, a cooling of the surface waters, is "roaring" in the equatorial Pacific, says Florida State University's James J. O'Brien, and that will impact storm tracks for the Mid-Atlantic and Northeast.

La Nina disrupts the upper-air jet-stream winds from the west that move storms. Jet streams form along boundaries of warm and cold air, and that mass of cool water in the Pacific forces those boundaries to the north, says O'Brien, a professor emeritus whose expertise is La Nina and its opposite, El Nino, which is a warming of the waters.

During La Nina, the winds tend to blow from Hawaii to Seattle and ultimately pass north of Philadelphia. In addition, a ridge of high pressure tends to build along the East Coast, and that heavier air suppresses coastal storms, the ones that produce the hefty snows along the I-95 corridor.

Snow-lovers need not despair, however. Although big storms have been scarce in moderate and strong La Nina years, it has snowed some in those years, according to Anthony Gigi, a meteorologist with the National Weather Service in Mount Holly. Overall average snowfall was just over 15 inches, which is within 75 percent of normal.

Air-pressure patterns in the far North Atlantic can trump the Pacific influence, says Gerry Bell, a seasonal forecaster with the government's Climate Prediction Center. High pressures near Greenland can drive cold air into the Northeast and set up a snowier storm track.

And winter fans also might find encouragement in the hurricane season. The consensus was that La Nina would enhance it.

The season got off to a strong start, but it fizzled at the end of September, and the government did not declare a single major hurricane disaster the entire season.