Thursday, December 08, 2016

Conditions Far Different This December vs December 2015

The conditions over the higher latitudes at 10mB (65-70,000 feet) are much warmer recently than last November/December...

Hat tip: Peter Mullinax
 ...which translates to higher heights aloft at 10 mB.

Pressure pattern completely the opposite of the polar conditions in early December last year where heights were much lower. Polar vortex was very stable probably influenced by the El Nino.

 Temperatures last December were well above normal across the eastern 2/3 of the US

In fact, over the last 6 Decembers, only 2013 and 2010 were below normal east and/or north.

So far, temperatures in early December through the 5th were above average.

Based on the high latitude conditions at 10 mb (65 and 70,000 feet) mentioned above and the higher than normal Eurasian snow cover which has driven skyrocketing high pressure across Russia, this first shot of colder air across North America was not a surprise.

Nearly Record Setting High Pressure Across Asia in late November

Graphic courtesy Greg Carbin, SPC

In fact, we mentioned this in our winter weather outlook issued back on October 27th and in subsequent tweets on November 22nd and Dec 2nd emphasizing a significant lake effect snow event a week in advance:

The CPC painted its first below normal temperature outlook across ALL of North America for the first time since December 2013. Hat tip: Brian Brettschneider

We haven't had a December with temperatures at least one degree below normal in Cleveland since 2010.

A few days ago (December 6) I retweeted a post from late November highlighting the shifting jet stream position across the middle of the US allowing more frequent storm systems.

Our 8day forecast issued on December 7th and 8th shows these individual systems with high snow potential for northern Ohio through December 16th and beyond.

Anticipate below normal temperatures, overall, the rest of December 2016. 80% Chance for a white Christmas for northern Ohio!