January 2020 Outlook: Projecting the Return of Winter!
It's hard to believe that Rocherster is still more than a foot of snow above average through the 28th day of December considering how warm the first "official" week of winter has started. Since December 21st have averaged some 10 to 15 degrees above the climatological norm for much of the eastern half of the North American Continent.
It seems an early winter thaw was inevitable considering the cold and snowy start to the season going back to early November where snow totals piled up to the tune of nearly 40 inches at the Rochester International Airport.
So what's next?
While upper level ridging has been the dominant player recently leading to the early winter thaw, those jet stream winds are expected to veer back around in the weeks to come with today's run of the Euro Ensemble forecast system showing deep troughing developing over the middle of the continent again as we head into the second week of January.
This is congruent with the current set up as sea surface temps (SST's) along both coasts of North America right now have large pools of above normal temps which are apparent over the Bay of Alaska, the North Atlantic and off the Eastern Sea Board of the United States.
All else being equal, this should generally lead to a pattern of "ridging" along the West Coast, immediate East Coast and over the North Atlantic... and a complementary pattern of "troughing" for central portions of the continent as we head into the weeks ahead.
Of the many "climate signals" we look at with medium range forecasting is the forecasted state of the North Atlantic Osciallation (NAO). Typically a positive NAO leads to progressive west to east systems across the US and corresponding fluctuations of both warm and cold temps. However, in order to see a sustained period of cold with snow potential, you typically need to see the NAO going negative.
Today's run of the GFS Ensembles shows a generally positive NAO through the first week of January before trending towards negative during the second week of 2020. This makes sense to me considering the current set up.
The current Euro (showing 1000-500mb heights) gives an approximation of the cold as it builds into Canada and eventually spilling into the Central US over the next couple of weeks as we wrap up 2019 and head into the new decade.
Looking ahead through the new month, start of the new year and decade... our friends over at the Climate Prediction Center generally agree with this assessmemnt of the cold returning for the Month of January with their current forecast featuring above average temps over the Pacific NW, South TX and SouthFL with below normal temps across much of the Northern Tier and Northeastern US for the month ahead.
So what do I think?
I think now is the time to enjoy relative warmth, easy travel and a nice break from the snow shoveling, b/c as the above data indicates, I don't think winter stays away to long. Be prepared for the cold to return in the next one to two weeks and once it does, it may not be in any hurrry to leave.
Lisa and I will be back with a full update on your New Years forecast and January 2020 Outlook on Sunday's WxLIVE at 8:45! See you then.