Groundhog Says: 6 More Weeks of Winter

Sunday had a Super mix of winter prognostications from North America’s bevy of rodent winter prognosticators, who emerged from their burrows on Groundhog Day to offer their predictions of an early or late end to winter. America’s most famous groundhog, Punxsutawney Phil, in Punxsutawney, PA had this to say:

“A Super Bowl winner I will not predict,
But my weather forecast, you cannot contradict,
That’s not a football lying beside me
It’s my shadow you see
So, six more weeks of winter it shall be!”


Figure 1. Canada's famous albino groundhog named Wiarton Willy from the town of Wiarton, Ontario. Image credit: wunderphotographer pincollector1.

Results of other groundhog forecasters
Wiarton Willie in Ontario, Canada saw his shadow, so 6 more weeks of winter.

General Beauregard Lee in Lilburn, GA, did not see his shadow, predicting an early end to winter.

Staten Island Chuck, AKA Charles G. Hogg, of the Staten Island Zoo, New York City saw his shadow, so six more weeks of winter. Chuck was dropped by New York City mayor Bill de Blasio, but was unharmed.

Buckeye Chuck in Ohio did not see his shadow, predicting an early end to winter.   

Shubenacadie Sam in Nova Scotia did not see his shadow, predicting an early end to winter.

Winnepeg Willow in Manitoba, Canada, did not see his shadow, predicting an early end to winter.

Dunkirk Dave in Dunkirk, NY, the world's second longest prognosticating groundhog, did not see his shadow, predicting an early end to winter. 

A quick look back at NOAA’s winter forecast issued in November
NOAA’s National Climatic Data Center (NCDC) analyzed Punxsutawney Phil’s forecasts over the past 26 years (thanks to Doyle Rice of USA Today for pointing this out.) If we evaluate just the eleven years both when the departure of February and March temperatures from average over the contiguous U.S. were both of the same sign, Phil had only three correct forecasts, and eight blown forecasts. NOAA concludes that “It really isn't a 'bright' idea to take a measure such as a groundhog's shadow and use it as a predictive meteorological tool for the entire United States.” But how well does NOAA forecast the winter weather? NOAA’s annual Winter Outlook, released on November 21, called for increased chances of a warmer than average winter across much of the Southern U.S. and New England, and a cooler than average winter across portions of the Northern Plains near the Canadian border. NOAA relied heavily on climate trends over the past fifteen years and long-range computer models such as their CFS forecast model to predict this year's winter weather. While winter is not yet over so we cannot yet fully verify this forecast, we can get a good idea of how well it is doing by taking a look at the actual departure of temperature from average for December and January (Figure 3.) The region NOAA gave the highest chance for a cold winter, the Upper Midwest, was indeed the area that experienced the coldest temperatures, relative to average. However, the two areas they predicted would have the best chances of above average temperatures—the South and New England—did not, so NOAA gets no points there so far. The latest NOAA 8 - 14 day outlook calls for a winter pattern very similar to what was observed in December and January: the east half of the national colder than average, and the west half warmer than average. We’ll call the verification of NOAA’s winter temperature forecast inconclusive at this point. Their forecast for precipitation, though, is right on so far over the Southwest U.S., where they called for drought to persist and intensify.


Figure 2. Forecast temperature and precipitation for the U.S. for the winter of 2013 - 2014 as predicted in the NOAA Winter Outlook, released on November 21, 2013.


Figure 3. Departure of temperature from a 1981 - 2010 average over the Contiguous U.S. during December 2013 and January 2014. An unusually kinked jet stream pattern brought colder than average temperatures to the eastern half of the country, and warmer than average conditions to the western half. Image credit: NOAA/ESRL.

I'm in Atlanta this week for the 94th annual meeting of the American Meteorological Society. I plan on being at Stu Ostro's poster on crazy jet stream shenanigans, being presented at 2:30pm Wednesday in Hall C3, if any of you reading this want to stop by and meet.

Jeff Masters