Six more weeks of non-winter

Here Ye! Here Ye! Here Ye!

On Gobbler's Knob on this magnificent Groundhog Day, February 2nd, 2012
Punxsutawney Phil, the Seer of Seers, the Prognosticator of all Prognosticators,
was summoned from his burrow in the old oak stump
by the tap of President Bill Deedly.

He greeted his handlers, John Griffiths and Ron Ploucha.

After casting an appreciative glance towards thousands of his faithful followers,
Phil proclaimed
As I look at the crowd on Gobbler's Knob
Many shadows do I see
So six more weeks of winter it must be!

That's the official word posted at groundhog.org from Punxsutawney Pennsylvania's famous prognosticating rodent, Punxsutawney Phil, who saw his shadow this morning. According to tradition, this means that a solid six more weeks of winter can be expected across the U.S. When the sun rises in San Francisco, this morning, wunderground's Alan T. Groundhog can give us an additional shadow-based forecast for the coming winter (video here.)


Figure 1. Wunderground's prognosticating groundhog, Alan T. Groundhog, prepares to go in front of the blue screen with wunderground meteorologist Jessica Parker.

How did this this crazy tradition start?
It all started in Europe, centuries ago, when February 2 was a holiday called Candlemas. On Candlemas, people prayed for mild weather for the remainder of winter. The superstition arose that if a hibernating badger woke up and saw its shadow on Candlemas, there would be six more weeks of severe winter weather. When Europeans settled the New World, they didn't find any badgers. So, they decided to use native groundhogs (aka the woodchuck, land beaver, or whistlepig) as their prognosticating rodent.

What winter? The non-winter of 2011 - 2012
Considering winter hasn't really arrived in the lower 48 states yet, I'm not sure how much validity we can give to fearless Phil's forecast. Here in Michigan, like in most of the U.S., we've basically had three straight months of November weather. There have been no major snowstorms, and frequent sunny days with highs in the 50s--twenty five degrees above average. January 2012 is in the weather record books as the 3rd least-snowy January for the contiguous U.S. since snow records began in 1966, the Rutgers Snow Lab reported yesterday, and December 2011 ranked as the 11th least snowy December on record. With the latest 2-week forecast from the GFS model showing a huge ridge of high pressure dominating the Western U.S. and no major snowstorms over the U.S. through mid-February, the winter of 2011 - 2012 has a chance to end up as the second least snowy winter in U.S. history. Temperature statistics for January will not be available until next week, but I expect the month will end up being a top-five warmest January, with temperatures about 4 - 5°F above average. We won't be able to beat the 8.7°F above-average temperature posted during the warmest January in U.S. history, which occurred in 2006. If U.S. temperatures remain 4 - 5°F above average during February, the winter of 2011 - 2012 will be the warmest in U.S. history. The five warmest U.S. winters since record keeping began in 1895 have all occurred since 1992, with the winter of 1999 - 2000 holding the record for warmest winter. Winter average temperature in the contiguous U.S. has been increasing by about 1.6°F per century since 1895 (Figure 2.)


Figure 2. Winter temperatures in the contiguous U.S. during the period 1895 - 2011 increased at a rate of about 1.6°F per century. The warmest winter was 1999 - 2000, and the coldest was 1978 - 1979. Image credit: NOAA/NCDC.

What's going on?
This January's remarkable warmth and lack of snow contrasts starkly with what happened during the previous two winters. January 2011 was the 5th snowiest and 35th coldest in U.S. history, and January 2010 was the 7th snowiest and 55th coldest. Wunderground meteorologist Angela Fritz had this to say in her blog post yesterday about what's been going on this winter: In December, we were reporting that the lower-48's unseasonably warm weather and lack of snow was due to a particularly positive Arctic Oscillation (AO) index. The Arctic Oscillation is a measure of the jet stream's strength. A positive AO is a stronger than average jet stream, and it tends to keep cold air bottled up in the Arctic. During a positive AO, the Arctic is colder than average, and the mid-latitudes are warmer than average. In December and early January, the AO was positive. In mid-January, the AO went negative, which we expect to have the opposite impact. A weak jet steam means cold, Arctic air can escape to the south, and that's what we've been seeing in Europe this week. This cold air has yet to spill southwards into the Eastern U.S. like it usually does during a negative-AO period, since the North Atlantic Oscillation (NAO)--the component of the AO over the North Atlantic--has not gone negative, and is close to normal right now. However, the long-range GFS model is predicting a modest cold air outbreak will occur over the Eastern U.S. around February 15.

Jeff Masters