A winter storm warning is in effect for Sunday — a blizzard warning for the Jersey Shore — and Sunday into Monday Philly’s snow has a shot at doubling the amount that fell on Jan. 25, the National Weather Service says.
“At this point, that’s certainly possible,” Zachary Cooper, meteorologist with the National Weather Service said Saturday. The official forecast is calling for just over a foot in the city, with the potential for the total reaching 18 inches.
Blizzard warnings up for the Shore, where onshore winds are forecast to howl past 35 mph, with moderate to major flooding possible.
While it wasn’t in the official language, the weather service on a Saturday morning might well have included a supermarket stampede warning.
The actual winter storm warning is in effect from 7 a.m. Sunday until 6 p.m. Monday.
With a surprising level of agreement computer models and their interpreters Saturday were seeing the storm as being inevitable. It was forecast to affect the I-95 corridor from Washington to Boston — a rarity in recent winters.
The weather service listed a 25% chance that totals could approach two feet in the city.
“It’s going to be a long-duration event,” said Cody Snell, meteorologist with NOAA’s Weather Prediction Center in College Park, Md.
On the plus side, this will not have the staying power of the 9.3 punitive inches that accumulated on Jan. 25 and spent a three-week vacation in the region. No ice is in the forecast, and daytime temperatures above freezing and the February sun likely will erase most it by the end of the workweek.
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What time would the snow begin in Philly?
Precipitation is expected to begin Sunday morning, said Snell, possibly as a mix of snow and rain that becomes all snow.
Snow may have a hard time sticking during the day, said Tom Kines, senior meteorologist with AccuWeather Inc., since temperatures will be near or slightly above freezing and the late-winter sun will be a factor, even it’s just a rumor in the sky.
Plus the ground won’t be especially cold after a Saturday in which the temperature may approach 50 degrees.
However, the upper air is going to be quite cold, Snell said, and when the snow is falling heavily, as it is expected to do Sunday night, “it will cool the column.”
He said areas that get caught in heavy snow “bands” would see the highest amounts.
What would be so different about this storm?
The storm is forecast to mature into a classic nor’easter, so named for the strong winds generated from the Northeast.
Nor’easters are the primary source of heavy snows along I-95, but the ones that produce heavy snow from Washington to Boston have been scarce lately.
“Over the past several years, they’ve been few and far between,” Kines.
The Jan. 25 storm was not a nor’easter per se, said Snell, but more of a case of the “overrunning” of warm air over cold air producing the snow and sleet.
John Gyakum, an atmospheric scientist at McGill University in Montreal and a winter storm specialist, said he anecdotally has seen a trend of coastal storms intensifying too far north to have much of an impact on the Philly region.
If that were the case, it could be a symptom of global warming, said Steve Decker, meteorology professor at Rutgers University. Storms form where cold and warm meet, and that may have been happening farther north lately.
In any event that evidently won’t be the case Sunday.
What could go wrong with the forecasts?
Are you new around here?
The storm consists of multiple moving parts, and as it bounds off the Southeast coast, it is due to intensify rapidly over the warm Atlantic waters.
Meteorologists advised it was still unclear precisely how intense it would become and what path it would take.
Forecast busts have been known to happen, including a famous one 25 years ago. On a Friday, the weather service warned of a storm of “historic” proportions to begin that Sunday.
What Philly got was about an inch of snow that fell over three uneventful hours.
In 2015, the head of the Mount Holly weather service office publicly apologized for a busted forecast.
However, in recent years, the region hasn’t had all that many serious snow scares.
In this case, expect details to jump around even as the precipitation is falling, but Snell said “confidence is growing” that substantial snow is going to happen.
Inquirer staff writer Stephen Stirling contributed to this article.
