Sunday, November 26, 2017

COLD.... It's Coming!

That headline makes it sound like it's a done deal, BUT I will remind you anything in the long range must be greeted with a little skepticism.  So why am I writing this post?  There is agreement between several models of a pattern shift during the first week of December.  Until then, it will remain quite mild given the time of year.

Remember, I said "cold".  NOT SNOW!  If there is any wintry weather, it's impossible to know until you get within a week to even discuss the possibility.  Last night on Twitter, I jokingly said the coming cold would make sense because by then, IT WILL BE DECEMBER!  It should get cold.  Remember the past 1 or 2 Decembers though.  2016 December temperatures were slightly above average (+.3°) and December 2015 was an incredible 9° above average.  If what I'm looking at verifies, we won't have a repeat of December 2015.

I'm only able to show you the Canadian and the GFS models.  There are rules about showing certain products from the European model and I don't feel like getting into a lawsuit over it.  Just know, the European is as cold and even colder than the Canadian and the GFS in the longer range.  Once again, greet long range forecasts with skepticism, but there is sound reasoning behind a cold air push the 1st week of December.

The GEFS ensemble valid noon December 9th shows the cold air going gangbusters.  Whenever you get a ridge poking up through western Canada and Alaska, look out!  The downstream trough is equally as strong.  This ridge dislodges the cold air and sends it south... via airmail.  See what I did there?

The 10-15 day GEFS ensemble temperatures just off the surface (December 6-11th) shows warming in Alaska as the ridge builds and the cold air increasing across areas along and east of the Rockies.  These are NOT temperatures displayed!  They are temperature ANOMALIES in degrees C.  This simply means the departure from average should be several degrees colder.

The Canadian shows the same thing in the 10-15 day outlook with a good chance for below average temperatures.  Look at the positive anomalies in Canada and Alaska.  It will still be cold there, but warmer than average.  The chill relative to average is sent south due to the pattern shift (ridge west, trough east)

In summary, all the major models are trending towards a colder solution after December 6-8th.  It's too early to pinpoint an exact timing, but it's indeed there.  Whenever arctic air gets involved, anything can happen.  However, it's way too early to speculate about anything frozen.  If we do end up with wintry weather, it would be completely normal since we are going into meteorological winter starting December 1st.

The Climate Prediction Center 8-14 day outlook only shows most of the United States with a high chance for above average temperatures.  Look for that to change soon.

Buckle up, winter is starting!  I can't wait! 

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