PHILADELPHIA – Above-normal temperatures in January:
Boston: 9 degrees above normal
Burlington, Vt.: 7.4 degrees above normal
New York: 6.5 degrees above normal
Chicago: 6.3 degrees above normal
Philadelphia: 5.9 degrees above normal
Regardless of whether Punxsutawney Phil does or does not see his shadow Sunday morning, the winter of 2019-20 indisputably has been a shadow of itself. And the higher-order mammals who forecast the weather say it is unlikely to change for the foreseeable future.
All winter, models have consistently promised cold shots, behaving something like the SEPTA app on a snowy day: When you get to the station its says the train is three minutes late, then five, then 20. Then the train is canceled.
“I’m not complaining,” said Mike Halpert, deputy director of the government’s Climate Prediction Center, whose winter forecast did favor above-normal temperatures in much of the nation.
Philadelphia’s official snow total through the end of January, 0.3 inches, was the lowest to date in 25 years, and only three other years were as snow-deprived through Jan. 31 in records dating to 1884. Snow deficits have been common throughout the Mid-Atlantic and Northeast, even in the Great Lakes snow belts.
Folklore has it that if groundhog Phil sees his shadow on Feb. 2, he will scurry back to his burrow and the nation can expect six more weeks of winter; if he doesn’t see it, expect an early spring. For what it’s worth, clouds are forecast to obscure the sun Sunday in Punxsutawney. And based on outlooks, the humans aren’t seeing any shadows.
It’s still very much there, doing what it’s been doing for millennia. It has been a major player, said Cohen, just not in the role it assumed in the winters in which it gained celebrity.
The vortex is a swirling cyclonic mass that allows cold air to build in the Arctic. On occasion some of that air breaks away and oozes deep into the United States riding a buckling jet stream. This winter, however, the vortex has been so strong that in effect it has been a cold-air dam.
The Philadelphia region has been affected by its share of winter storms – it’s just on the wrong side of them for snow.
“A lot of these storms have been cutters,” said Dave Dombek, a meteorologist with AccuWeather Inc., so called because they “cut” to the west. “They’ve been heading up to the Great Lakes, Ohio Valley, west of the mountains.”
Winds circulate counterclockwise around centers of low pressure. Areas to the east – in this case that would be the likes of Washington, Philadelphia, New York, and Boston – get warming, sometimes very warming, winds from the south.
An area of higher pressure, or storm-discouraging heavier air, has persisted over the Southeast, repelling snowmaking nor’easters, said Dombek. It has been quite warm down that way, save for the night of the falling iguanas on Jan. 22, when temperatures dropped to 40 in Miami.
“In this climate-change environment it’s been proving hard to get sustained cold,” said AER’s Cohen.
“The planet is warming. That’s indisputable,” said Halpert. That’s one reason the climate center’s seasonal outlooks have tended to favor above-average temperatures.
Global temperatures have increased at the rate of about 0.3 degrees Fahrenheit per decade since 1981, according to the National Centers for Environmental Information. The 2019 global temperature was about 1.7 degrees higher than the 20th-century average, a difference of about 3%.
But while the planet has less of it, it still has a generous supply of cold air available.
And while going warmer in a winter forecast generally is a safe bet, if you keep going with it, said Halpert, “some years you’re going to be woefully wrong.”
Snow isn’t all that frequent around here in any winter. On occasion a megastorm can be a showstopper, but officially Philadelphia has only five days a winter with snowfall of an inch or more.
“The fact that snow comes so infrequently, it has such a huge interannual variability,” said David. A. Robinson, a Rutgers University professor who has become an international go-to person on snow matters. In the winter of 2009-10, a record 78 inches was measured in Philadelphia, or 260 times what has fallen so far this winter.
By contrast, there were virtual snow shutouts in Philadelphia through Jan. 31 in 1898-90 and 1994-95.
“People say it never happens,” Dombek said. “Sure it has.”
Along with energy-bill savings, this has been a great season for the aching backs of those who must shovel.
And with all that cold locked in by the North Pole, says Cohen, it should be a relatively good season for the build-back of Arctic ice.
The abject wimpiness has made a mess out of winter outlooks, but Cohen said his forecast for above-normal snowfall for the Northeast might have positive consequences.
Said Cohen: “You learn more from your failures than your successes.”
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