A bitter, brutal forecast: After 'bomb cyclone,' it's only going to get colder

A man turns his face away from the blowing snow and struggles to walk along Atlantic Ave. in Atlantic City on Thursday.

After heaping a season’s worth of snow upon the Jersey Shore, as a parting shot the “bomb cyclone” yanked open the freezer door.

The bruising storm that blanketed the region Thursday — doing the same along much of the East Coast — left in its wake stinging west winds that will howl across the granular snow cover for the next two days, forecasters said. The National Weather Service predicted “dangerous” wind chills that it said might not inch above zero until daybreak Sunday.

“We could have blowing and drifting snow through Saturday,” said Alan Reppert, a meteorologist with AccuWeather Inc.

The fast-moving storm shut down large swaths of Southeastern Pennsylvania and South Jersey, including most schools, as well as courthouses and many public offices. And the forecasts of relentlessly punishing cold prompted many, including Philadelphia City Hall, to declare they would be closed on Friday.

Temperatures will be about as low as they get around here, and records could fall during the weekend. The city has an outside shot at recording its first official zero-degree reading in a generation. The forecast low of 1 on Sunday would beat the record of 4 for a Jan. 7, set four years ago.

The agent provocateur of the impending deep freeze is the powerful winter storm that intensified so rapidly that it qualified as a meteorological “bomb,” the product of what the weather people call “bombogenesis.” It is forecast to keep spinning off the Nova Scotia coast the next few days, its circulating winds importing mass quantities of frigid air from central Canada.

“It’s helping to bring the cold air from northwest to southeast,” said Robert Oravec, senior forecaster at the government’s Weather Prediction Center.

It also brought prodigious amounts of snow along coastal areas from the Mid-Atlantic to Maine, with 17 inches reported at Cape May Court House — about what would fall on average during an entire season.

The inland totals were less impressive, with 3 to 5 inches common in the immediate Philadelphia area. However the snow turned out to be heavier — in terms of water weight — than expected, said Joe Miketta, acting chief of the weather service’s Mount Holly office. Usually, with temperatures as cold as they were Thursday, the snow is drier. Shoveling 4 inches felt more like 8, and the liquid content of the snow might have made even treated surfaces more hazardous, he said.

All this was enough to keep many people home — and those who did venture out found perilous driving conditions. A car passenger was killed when the vehicle, unable to stop at a crossing gate, was involved in a collision with a SEPTA train in Lower Moreland Township, police said. Southbound lanes of the Northeast Extension of the Pennsylvania Turnpike were closed between Quakertown and Lansdale because of an overturned tractor-trailer.

“We have traffic accidents and stalled vehicles on roadways all over the place,” added Timothy Boyce, the Delaware County director for emergency services. “The Blue Route has been a mess all day.”

SEPTA canceled several bus routes, and Regional Rail delays were common. At Philadelphia International Airport, 225 incoming and outgoing flights were canceled.

 

A Deep Freeze, Then a Return to Normal

Temperatures in Philadelphia are expected to plummet after the “bomb cyclone” passes through, with a wind chill of -12 degrees forecast for Saturday morning. Then temperature are expected to recover by Monday, going several degrees above freezing for the first time since Dec. 26.
Staff Graphic

The freeze is forecast to ease Monday, when temperatures head toward the upper 30s, but it’s going to be quite a cold wait.

The coastal storm is working in tandem with its opposite number, an impressive area of high pressure, to open the floodgates to the frigid air.

While the concept of barometric pressure has all but evaporated from the public consciousness — yielding to catchier terms such as “polar vortex” and “bombogenesis” — the weight of the air is a critical component of weather. The lighter the air, the better for the rising air currents that produce rain and snow. Heavier air has the opposite effect.

What drives winds is the contrast between high and low pressure. In this case, the pressure differences between the storm and high pressure to the northwest as about as extreme as it gets on the planet.

Heavier air moves toward lighter air, and we are getting caught in the west-wind crossfire.

Winded gusted past 50 mph at the Shore on Thursday, causing blizzard-like conditions. However, it will take a day or two to determine whether actual blizzard criteria — 35 mph winds and quarter-mile visibility — actually were met, said Sarah Johnson, a lead forecaster at the Mount Holly office.

The 4 inches of snow measured at Philadelphia International Airport raised the seasonal total to over a foot. On average, just under 5 inches has fallen through Thursday in Philadelphia.

Ironically, Miketta said, the early start to the snow and extreme cold is an echo of the summer of 2017, when the upper-air pattern of generally lower pressures favored comfortable temperatures.

Comfortable will not describe the next few days, when sustained winds up to 25 mph with gale-force gusts are expected across the region Friday and Saturday as temperatures remain in the teens.

Only 75 days until spring.

Staff writers Joseph A. Gambardello, Patricia Madej, and Erin McCarthy contributed to this article.

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