Looking at the longer range data it appears that a significant portion of the country will experience a very cold middle of December. Will the N/E be included?
Well it’s been a warm November. Barely any snow and almost no snowmaking conditions. Plain and simple- if you like to ski – this November sucked.
However longer range data indicates that a deep pocket of really cold air will flow into the CONUS in the next two weeks or so.
Starting next week it appears that the majority of the country will cool down to more seasonable temps. Beyond that however things get quite interesting. Around day 10 a deep polar vortex will slide down into Northern/NW Canada. Temps at 5000ft will be -40c (which oddly is also -40F). This deep pool of cold air will swing down through the west and into the central plains.
The AO ensemble forecast supports this deep influx of arctic air:
As you can see the this teleconnection pretty much plunges off the edge. A deeply negative AO indicates a cross polar flow and the intrusion of arctic air.
The questions at this point are 1) Will the cold air make it to the NE and 2) will it lock in?
1) The concern I have is that this cold air will settle in the central plains. A strong southern jet (typical of el nino) would then bring warm ocean air around the southern end of the trough of arctic air, flooding the NE with mild air, while storms feed off the contrast in air and pound the Ohio Valley. Too soon to tell on this feature,but it would sure suck to see Today Show features about Fargo ND sitting at -30 while I prepare to walk to work without any gloves on.
2) If the cold air makes it to the NE will it lock in? For this to happen we need downstream blocking. The NAO is the best blocker we have. It’s the Orlando Pace of weather blockers.
The NAO forecast:
Looking at this forecast we do see a drop to the negative phase indicating some blocking but then we see a return back towards positive. This indicates that after a brief few days of shrinkage inducing cold we would lose the blocking. (Though in the swings from one phase to another we do get some awesome storms).
One last point- if the PV (polar vortex) settles more in the west, the NE would really warm up via downstream ridging. (Rule I follow: Good ski weather out west, bad ski weather out east). Also, if the PV were to retrograde back up into the Yukon the flow around it and the southern stream energy would FLOOD the country with mild PAC air. YAY fifty for a high and 42 for a low.
Anywho…long story short. Look for a right cross of real cold air in the next few weeks after a week or so of seasonal temps. Then look for the development of a more mild pattern as we head into the final 1/3 of December.
UPDATE: I’m really beginning to think the core of the cold air will not settle into the east coast. Long Range we’re looking at another “lakes cutter” next week followed by some LES and mabye another glancing blow of “cool” air.
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