With the caveat that seasonal forecasting remains an elusive enterprise, the government offered some comfort Thursday to the region’s energy consumers and winter-phobes.
The Climate Prediction Center said the odds are favoring above-normal temperatures from the Mid-Atlantic and Northeast. And, no, it did not venture a guess on snowfall.
The climate center’s Mike Halpert said a burgeoning La Niña, a vast area of below-normal sea-surface temperatures in the tropical Pacific, is likely to be a major player during the winter.
Since weather moves west-to-east, whatever happens over a continent-size patch of the Pacific affects the atmosphere over North America.
Based on the 20 winters since 1950 that coincided with La Niñas, the results around here have been decidedly mixed.
They included the wimpy winter of 1988-89, which featured above-normal temperatures and just 11.2 inches of snow in Philly, about half the long-term average.
They also include the winter of 1995-96, when temperatures were substantially below normal and snowfall came in at 65.5 inches.
One reason the climate center has painted such broad areas of the Northeast and Mid-Atlantic with warmer hues is the pattern of the last 30 years, Halpert said. La Niña-influenced winters have trended warmer. Again, however, no clear trend has been evident in Philadelphia, with almost an even split between winters that were warmer and cooler than average.
For what it is worth, one characteristic of La Niña and El Niño winters has been persistence, as in what happens tends to keep happening, but Halpert said that effect appears to be stronger with El Niño than La Niña.
Even if La Niña did take hold, it hardly would be the only winter player. Snow, cold, and the lacks thereof are closely tied to shorter-term air-pressure patterns over the Arctic and North Atlantic, which, in turn are driven by other variables.
Thus it is not surprising to see a lack of consensus.
Take your pick; the atmosphere will make the choice in its own nonlinear chaotic way.