Snow and then 'thundersnow' hits Philly and region

The region was well-braced for an attack from nature, but what happened Wednesday qualified as an all-out ambush.

Snow started spreading across the region before daybreak, accumulating up to a half-foot by lunchtime, surprising highway crews and meteorologists.

And that was the appetizer before the main event that got under way after dark. Several inches of fresh, wind-driven snow, incited by "thundersnow" downpours, fell upon parts of the region. On Thursday, people in some areas are going to be shoveling their way out of a foot of snow.

The night attack was expected. The morning was something else.

"Obviously, we're going to go back and look to see what happened," said Gary Szatkowski, the meteorologist in charge of the National Weather Service office in Mount Holly, which had called for light accumulation during the day.

The morning round was juicier and whiter than foreseen in computer models, he said.

"Thundersnow" is literally a snow thunderstorm. Thunderstorms occur when violently rising air condenses into precipitation and sets off lightning. They are more common in spring and summer, when more heating is available, but can occur during winter storms and can deposit from two to five inches in just an hour.

The snow was heavy enough Wednesday night that Philadelphia public schools and administrative offices will be closed Thursday, spokesman Fernando Gallard said.

Early Wednesday evening, the Pennsylvania Department of Transportation temporarily ordered speeds reduced to 45 m.p.h. on interstate highways in the area. The same limit was temporarily imposed on the Pennsylvania Turnpike, according to the Associated Press. The New Jersey Turnpike cut speeds to 35 m.p.h. on the southern part of the highway.

The snow blitz was a nightmare for the Wednesday morning commuter rush, forcing some schools to announce at the last minute that they were closing or opening late.

Others that opened on time, including Philadelphia's public and Catholic schools, sent children home at noon.

Some government offices, including Delaware County's, shut early.

Even emergency crews had difficulty navigating the slippery roads in Chester County, where some of the heftiest snow totals were reported, and officials reported the usual spate of accidents, including one involving an ambulance.

A Gloucester Township police officer was struck by a car and suffered minor injuries while investigating a crash on an icy road.