Tuesday, May 26, 2015

White Christmas prospects

The math argues against it; the atmosphere may disagree.

White Christmas prospects

At 7 a.m. on Dec. 25, 2009, the official snow depth in Philadelphia was 7 inches, the leftovers from the colossal storm of the previous weekend.

Should measurable snow be observed at 7 a.m. this Dec. 25, it would mark the first time since 1966 that Philadelphia had consecutive White Christmases.

In any given year, the smart money would be on bare ground. On average, Philadelphians can expect a Christmas-morning snow cover about once every seven years.

If we include those occasions on which measureable snow fell on Dec. 25 sometime after 7 a.m., Philadelphia, the chances of seeing Christmas snow on the ground increase to about 1 in 5.

This year, however, it is a genuine possibility. Those whimsical computer models have backed off the weekend snowstorm for now, but don't be at all surprised if they bring it back later today or tomorrow.

The government's 6-to-10-day outlook, valid through Christmas Eve, continues a call for below-normal temperatures and above-normal precipitation.

That certainly doesn't mean it's going to snow in that period, but if it does, it may well stick around for awhile.

Rod Phillips at Stormfax was kind enough to pass along a tidy summary of Philadelphia Christmas snows since 1958.



Inquirer Weather Columnist
About this blog

Everyone talks about the weather, and here we write about it.

When we’re around and conditions warrant, we’ll keep you updated about what’s coming, but we will do our best always to discuss weather and climate developments in context and remind you that nothing in the atmosphere happens in a vacuum.

Tony Wood has been writing about the atmosphere for The Inquirer for 26 years.

Reach Tony at twood@phillynews.com.

Tony Wood Inquirer Weather Columnist
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