Remember the winter after the Long Winter?
It was described in Little Town on the Prairie. If you’re struggling to remember it, don’t feel bad — there wasn’t much of a winter there at all. Laura describes mild temperatures and little snowfall during the winter of 1881-82. The Ingalls family, once bitten by the Long Winter, are twice shy; they prepared carefully in the fall of 1881 for another brutal winter. Haystacks were moved to town, along with livestock and accidentally discovered Christmas presents. Fuel and food supplies were laid in, and family battened down the hatches.
And then… nothing.
Mild days passed by into mild months, with little precipitation. The winter of 1881-82 stands among the top 5 or 10 mildest winters across the region, which is even more remarkable of a feat because the decade of the 1880s is the coldest in modern records, with a number of years among the top 5 to 10 coldest winters in the region. It was mild even by the standards of today’s climate, let alone the cooler climate of the late 1800s.
We have reached spring, and the winter of 2011-12 is shifting to the rear-view mirror. It was among the mildest on record across the country, with a persistent lack of snow cover and a noticeable deficit of Arctic air. For many Plains dwellers, it was a relief after the cold and snowy winters of 2009-10 and 2010-11 that preceded it. March might very well be the warmest on record across much of the northern U.S., with record warm temperatures dropping like the skiers I see out the window*.
What happened to winter this year? Where did it go?
Many of you know that meteorologists watch the higher levels of the atmosphere carefully to track the river of air known as the “jet stream”. There actually is not usually just one jet stream, but rather several. The northern one, known as the “polar jet”, tends to be up around Canada in the winter, dropping into the U.S. to bring the coldest of air for a visit. The southern one, known as the “subtropical jet”, locks in somewhere around the latitude of the Gulf Coast. As you can guess, it can bring warmer and wetter air in from the tropical oceans. A really good storm (that’s meteorologist-good!) can occur when the two jet streams converge, which we weather weenies call “phasing”. The cold air from the polar jet combined with the moisture from the subtropical jet sets up the nastier of storms.
This year, the jet streams stayed in their separate corners, which the weather weenies call “split flow”. When we had a storm system that brought moisture up from the oceans, the cold air was locked away to the north. The two did not cooperate, which means that they did not bring impressive snowstorms and cold outbreaks to the U.S. We also held onto a positive, or warm, North Atlantic Oscillation throughout the winter, keeping us on the warm side even when the related Arctic Oscillation fell out of step and went negative, bringing a rough cold outbreak to Europe in February.
The early bloom across the Plains does have a few of us worried that a late freeze (especially a hard freeze) could damage some of the premature plants. Recall that after the careful preparation for a hard winter that never materialized, the Ingalls family moved back to the claim early that spring… where they were hit by a late spring blizzard. We have no blizzards on the horizon, but cold snaps late in the spring are still possible. Keep a wary eye on your tender vegetation through the spring!
*I am currently on a brief vacation in Utah to visit a friend, and while my husband and our friend are skiing, I’m cozied in the lodge with a panorama of snow-capped mountains, skiers of varying abilities descending slopes of varying grades, and chair lifts. It’s an inspirational winter scene in the midst of a very summery spring.