Meteorological winter arrives Friday: 50 degrees, then Arctic next week
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A quick chat with your local meteorologist and it's obvious. We march to the beat of a different weather drummer. So why wouldn't we invent our own seasons?
The coldest 3 months of the year in the northern hemisphere are December through February. With annual temperature cycles, it's more accurate to break up the seasons this way. Our own alternative weather facts. So December, and "meteorological winter" arrive Friday. Yes, my name is Paul Huttner. And I'm a weather geek.
NOAA elaborates on why meteorological seasons differ from astronomical seasons.
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You may have noticed that meteorologists and climatologists define seasons differently from “regular” or astronomical spring, summer, fall, and winter. So, why do meteorological and astronomical seasons begin and end at different times? In short, it’s because the astronomical seasons are based on the position of Earth in relation to the sun, whereas the meteorological seasons are based on the annual temperature cycle.
November whiplash
Our Jekyll and Hyde November contained two distinct temperature personalities. The turnaround from early November chill to balmy breezes is remarkable.
It seemed impossible two weeks ago, but our mild weather this week assures that November will actually finish slightly warmer than average in most of Minnesota. Talk about a comeback.
December temperature shock ahead
December arrives Friday with more balmy breezes. It looks like early December may be ready to continue the trend of weather whiplash that November started. Highs in the Twin Cities will push 50 degrees Friday through Sunday. That's almost 20 degrees warmer than average for early December.
Jet stream buckles next week
The upper air maps predict a major shift next week. The balmy Pacific flow regime we've been basking in for about two weeks is about to radically change. Watch this loop from 500 millibars (about 18,000 feet aloft) transition from balmy to frigid over the next week. Note the cold (blue) vorticies spinning south from the Arctic Circle.
The latest NOAA temperature forecast reflects the cold air intrusions in the eastern half of the U.S. as we move deeper into December.
The latest NOAA GFS 16-day output cranks out slightly sub-zero numbers for the Twin Cities on about 10 days. Since we're on the backside of the developing trough, the pattern may also be relatively dry. Models suggest some light snow around December 10.
If this pattern verifies, lakes could see some good ice in about weeks. The lack of snow could be a boost for ice skaters and ice boaters in Minnesota.
Stay tuned.