Monday, December 13, 2010

Round #2: Lake Effect And the Arctic

How the patterns have changed.  November was great.  No winter weather.  Milder temps.  Now another big round of lake effect snow; the second one in a little over a week!
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 Why the big change?


Let check out the temps compared to normal for November.  Fairly mild and uneventful.



 Most of us thought we'd make it well into December without getting lake effect.  We thought wrong!

Why the sudden change?

If you remember our winter weather outlook back in early November, we hinted at a HUGE dramatic change in the weather pattern in December and January driven by La Nina and the Arctic.

The pressure systems over the arctic change randomly. In the winter, those changes are more pronounced.

Below is a picture of how the temperatures over the arctic change the movement of the storms over the US and northeastern Ohio.  When the arctic is "NEGATIVE", it steers storms and cold air south just like our weather over the last week.
The arctic has "dipped" negative several times since September but no big weather changed occurred. 


This last "dip" in December is significant. Notice the temperatures so far compared to average.


The arctic has the potential to get more "negative" pushing COLDER AND COLDER AIR SOUTH through Christmas and the New Year.


Looking back at the DECEMBERS (17 Decembers total since 1950) in which the arctic was this strong this early in the season, we find that the temperatures are WELL BELOW NORMAL.


THE BOTTOM LINE:  LOOK FOR THIS COLD AIR AND FREQUENT LAKE EFFECT SNOW TO CONTINUE AT LEAST THROUGH CHRISTMAS AND POSSIBLY INTO EARLY JANUARY

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