Snow tonight? Uh, really???

Posted: March 08, 2013

Must have been a lot of grousing this morning by local schoolkids unhappy to wake up and see ... nothing.

No snow.

Forecasts of two to six inches of snow for Philadelphia and its suburbs proved closer to scoops of pixie dust than blankets of sleddable crystals.

The word snow failed to even get a mention in the hourly reports overnight for airports in Lancaster, Pottstown, Philadelphia and Mount Holly.

Good thing forecasters restrained themselves from citing a computer model that predicted 15 inches of snow, said Anthony Gigi, meteorologist with the National Weather Service in Mount Holly.

"We were playing it more conservative than most of the models were showing," Gigi said. "I guess we weren't conservative enough."

The Jersey Shore, though, did get damaging winds and flooding as predicted, blowing off part of a condo roof in Stone Harbor, breaching a dune and flooding a road in Mantaloking, and causing at least 20,000 customers to lose electricity.

"That part of the forecast unfortunately worked," Gigi said.

This morning, Gigi was downplaying a possible rain-to-snow-to-rain event perhaps lingering from this afternoon to Friday afternoon, with snow possible during the morning rush.

"I don't know if you would even call it a nuisance event," he said. An inch or two of snow might stick to lawns, and people might have to wipe snow of their cars. "Maybe," he said.

This isn't a new storm, but the lingering effects of "our forecasting nemesis," a low still hanging off the Atlantic Coast, he said.

The forecast was way off for several reasons.

"Basically, it's a domino effect that you needed to occur for it to snow here," he said.

It wasn't that the track shifted or the storm sped through.

"There wasn't enough heavier precipitation to cool the air mass to the point that it would change to snow and keep on snowing," he said.

"It was obvious there was a dearth of available cold air to be ingested into the system," he said. ". . . Once that didn't happen all the wheels just fell off the cart."

The storm wound up being more focused - less widespread - than expected. It was far from a dud, since it dropped a foot of snow near Pittsburgh and in parts of Virginia, with two feet reported in West Virginia. But Washington, D.C.'s panicky closing of government offices proved to be unwarranted.

Also, forecasters serve two masters who are often in conflict.

"There is a balancing act that goes on between informing the public and accuracy in snowfall forecasts," Gigi said. The sooner the warnings, the better for preparations - but the worse for precision.

With this storm, the confidence level was always low.

Even Wednesday morning, a weather service note cautioned, "Normally, as we get closer to the event, confidence increases. However, this is one of those anomalous events, where that is not necessarily the case." It even advised, "portions of the region may not see much at all."

March is somewhat of a forecasting hell.

"In May, when we make mistakes, the mistakes just go down the drain," Gigi said. "In March, you open the door and the mistake hits you in the face."

Remember the so-called hyperstorm of 2001, which TV meteorologist John Bolaris infamously warned could produce paralyzing piles of snow? Instead, it mostly missed Philadelphia, though New England did get socked. That was on March 5.

This winter, snow forecasts generally have erred on the high side.

Although that might suggest a particularly difficult season, a colleague suggested that tricky winter storms are the norm for Philadelphia, Gigi said.

The winters of 2009, 2010 and 2011, where forecasters nailed predictions of major snowfalls, those might have been the exceptions.

For more on the forecast, go to www.philly.com/weather.


Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.

 

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