Snow and cold may be lacking this winter in Philly and the Poconos, early outlooks say
The Tonga undersea volcano is a wild card, among others. And have these seasonal outlooks ever been wrong?
Snow lovers in the Philly region and Poconos ski operators may be getting another cold shoulder from the winter of 2022-23, but as a consolation, they also could be getting a break on heating costs.
At least that’s according to the very early winter outlooks posted by AccuWeather Inc. and the government’s Climate Prediction Center.
And have they ever been wrong?
» READ MORE: Winters around in the Philly region tend to be non-conformists
AccuWeather is calling for below-average snowfall in Philly — 14 to 20 inches; normal is 23 inches — and temperatures for the Dec. 1-to-Feb. 28 period to average better than 3 degrees above normal.
The climate center has odds favoring above-average temperatures, with just a 22% chance that they’ll be lower than normal.
But this winter’s outlooks are especially challenging, Paul Pastelok, AccuWeather’s seasonal forecaster, said Thursday.
Aside from the standard nonlinear chaos, this time around the winter wild cards include the unusual behavior of the tropical Pacific and the fallout from a perhaps unprecedented volcanic eruption that shot water vapor to the outer edge of the atmosphere.
As if we didn’t have enough to worry about.
The Tonga effect
When the undersea Hunga Tonga-Hunga Ha’apai volcano blew back on Jan. 15, it ejected a massive plume of water vapor into the stratosphere, enough to fill 58,000 Olympic swimming pools, as high as 33 miles above Earth’s surface, according to NASA.
Said NASA scientist Luis Millan, “We’ve never seen anything like it.” The space agency speculated that the eruption in the South Pacific could temporarily raise Earth’s temperature slightly.
“Water vapor generally holds heat,” said Pastelok. “Does it act as a blanket?” Just how it has been affecting global temperatures remains unclear, let alone what it means for Philly and the ski areas of the Poconos and Catskills, where AccuWeather also is calling for below-normal snowfall.
But Tonga aside, worldwide warming in general already is evident in local temperature data. For 1981 to 2010, the 30-year period used to calculate climate “normals,” Philadelphia’s December average temperature jumped 1.1 degrees, compared with the previous 30-year data set.
‘Triple dip’
Waters in the tropical Pacific are expected to remain cooler than normal for a third consecutive winter — a “triple dip” La Niña — something that has happened only twice since 1950, according to the climate center’s records.
Temperatures are about 1.5 degrees below normal over thousands of miles of ocean.
What happens in the tropical Pacific does have profound effects on weather in the United States as sea-surface temperature anomalies interact with the overlying air, distorting system-bearing upper-level winds.
The triple dip is a mixed signal, said Pastelok, but the available evidence slightly favors a warmer winter around here.
The region had quite a cold and eventful season during the last triple-dip episode in the winter of 2000-01, which included a major snowstorm in late December in Philly during which western Chester County saw barely a flake.
The other triple dip occurred during the winter of 1975-76, which was generally mild and uneventful, but it did feature a March storm that produced Philly’s first six-inch snowfall in nine years.
» READ MORE: It was quite the January at the Shore
La Niña aside, snow around here is almost always a lottery situation. Last winter, for example, while a paltry 12.9 inches landed at Philadelphia International Airport, Atlantic City set snow records in January.
October surprises
Already this fall, the atmosphere has shown its skills at playing dodgeball with forecasters.
“It’s going to end up a little cooler than we thought in October,” said Pastelok.
The climate center has the odds favoring below-normal temperatures for the month, with strong high pressure over the Northwest generating winds from the cooler regions of North America to the Eastern United States. The average temperature for the first five days of October in Philly, 54.8 degrees, was more than 8 degrees below normal, and a significant cool-down is due this weekend, when readings could fall to the upper 30s outside the city Sunday morning.
Perhaps more puzzling is the state of the Atlantic hurricane season. Tropical storm outlooks have fared well in recent years, but Ian notwithstanding, storm numbers are almost certain to fall well short of those in forecasts that called for a hyperactive season.
» READ MORE: Early on forecasters were bullish on a busy hurricane season
Don’t blame Tonga, said Philip Klotzbach, tropical storm specialist at Colorado State University. That largely was the result of a so-called tropical upper-tropospheric trough, a source of strong upper-level winds from the west that has had both drying and shearing impacts on incipient storms.
Not to mention its shearing impacts on the outlooks. So far the season has produced 10 named storms, those with winds of 39 mph or greater; the average for early October is 11.
“Everybody busted on that,” said Pastelok.
They do keep trying.