Think back to a year ago. Snowstorm after snowstorm had accumulated in January like layers of a frozen parfait until we were all half-blinded by the drifts and shuttled into narrow lanes on the roadways. It was frustrating, it was dangerous and it was epic — one of those winters we'll all remember.
Take a look outside today. Not a flake to be seen. The grass, if not exactly green, still has some color to it. The flowers are confused; the birds are dysfunctional; and we won't even begin to talk about the bears.
So did the universe just decide we'd had enough after 2011's terrible trifecta: White-Out Winter, Tropical Storm Irene and Snowtober?
Not exactly. Weather experts have laid the Lower 48's mild winter at the door of a phenomenon known as Arctic Oscillation, which is also to blame for the huge snowfall in Alaska this year.
NASA's Science News website says that "Arctic Oscillation is a see-sawing pressure difference between the Arctic and lower latitudes. When the pressure difference is high, a whirlpool of air forms around the North Pole. Last year, the whirlpool motion was weaker, allowing cold air to escape from the polar regions and head southward to the U.S."
As explained by meteorologist Jeffrey Masters to NPR, Arctic Oscillation also "drives the jet stream and controls how strong its winds are and where the jet stream position is."
If the jet stream moves south of us, we tend to have a colder winter with heavy snow. If the jet stream is pushed north of us, subtropical air stays in play and keeps the winter mild.
Masters told NPR that the Arctic Oscillation can only be predicted a week or two out, so there's a chance that we could see a change by late February. But for now, we're on a track to have the warmest winter on record in the United States.
