Perhaps Phil was on to something. Around the time that he was routed from his burrow and coerced into seeing his shadow and forecasting six more weeks of winter, the upper atmosphere over the Arctic became dramatically warmer.
Whether this was related to larger trends in the Arctic is unclear, but meteorologists say it was the onset of a so-called sudden stratospheric warming, or SSW, that set off a chain of events that have resulted in March’s bonding with its inner February.
Thus, the tired remnants of last week’s snow persist in parts of the region, and they might well get reinforcements next week as forecasters are warning of another potential coastal storm in time for the arrival of spring equinox on Tuesday, which happens to coincide with the 60th anniversary of the 1958 Equinox Storm, one of the more disruptive on record in the region.
Meanwhile, the government’s Climate Prediction Center and private forecasters are telling us to get used to this.
The climate center’s seasonal outlook released Thursday says spring is coming, with odds tilted toward above-normal temperatures in the April-June period.
But its latest forecast for the next two weeks calls for below-normal temperatures to continue in much of the nation. Philadelphia is not expected to get out of the 40s at a time when average highs climb well into the 50s.
For now, the wintry pattern is on hold
The chain of events that led to this is immensely complicated, but meteorologists say the SSW was the driving agent, helping to establish an air-pressure pattern over the North Atlantic Ocean that is delivering cold air to the East.
It is also creating conditions favorable for coastal storms, then impeding their seaward progress. That’s why we’ve been whip-lashed so much lately. In fact, for the month, sustained winds are averaging about 15 mph, well above average even for March.
SSW’s occur on average about once a winter, says Craig Long, stratospheric specialist at the climate center, although not every winter. It takes weeks for the effects to ripple through the lower latitudes.
We’ve felt the ripples. For the month, temperatures are averaging close to 3 degrees below normal in Philadelphia, and snow is better than double normal.
In New England, some of the snow totals have been staggering. Mount Snow reports that it has received 68 inches in just the last seven days — close to half the normal for an entire season.
More snow is possible next week in the Philadelphia region as yet another powerful coastal storm is possible.
The details remain unclear this far out, which is unsurprising. But those Mount Snow totals are at least as unlikely as an early spring.