After the SECOND winter storm this November, which dumped anywhere from 1-6 inches N & W of the I95 corridor, we are about to enter a warmer and quiet regime to start December. As expected, the “pattern change” people were harping on and on about to occur in early December is not happening , sound familiar?
As I suspected, the Gulf of Alaska low has CLEARLY redeveloped , this will lead to a train of storm systems and troughs swinging into the western US ,a return of a strong Pacific jet stream and an overall ridging/zonal pattern across the east just in time to start December .
Also as expected, the MJO has circled into phase 2 and is expected to go through phase 3 and 4, this is NOT what you look for to get a cold and snowy pattern going in the east. This supports my thinking that we will continue to be in a zonal pattern through late December, the only thing that is truly going to stop us from getting too warm is a transitional NAO block and a negative AO , which will help to drop an occasional cold front through the Midwest and Northeast, and we will see this over the next 2+ weeks with a lot of ups and downs in temperatures
If you want cold and snowy pattern you want this is phases 7 , 8 and 1 with convection around the dateline which would fire up a trough around the Aleutian Islands , causing a positive PNA ( ridge in the east Pacific/West coast) and a trough in the east , however where it is and where we are going supports a dominant trough along the west coast , with zonal/ridging for much of the country east of the Rockies , which increases the chances of storms going up into the Great Lakes instead of along the east coast, and this would lead to occasional warm spells ahead of these storm systems.
Behind these storm systems , cold fronts would come through and carve out troughs over the Northeastern US , and with the transitional negative NAO and AO these troughs will bring in plenty of cold air with the polar vortex on our side of he North Pole and with backing, our troughs and cold shots will linger a bit longer than they usually ould with a pattern like this, but after a few days the zonal pattern would take hold again and we would warm up, another storm would head into the Great lakes region, wash rinse repeat, this is what I expect through at least December 15th if not later .
We see the general up and down pattern in the NAO , again not what we look for to lock in a trough over the east
And the continuation of a negative PNA pattern
Until we get rid of the vortex in the Gulf of Alaska and over Alaska we are not transitioning to a dominant cold and snowy pattern , just plain and simple that will keep the PNA negative and with a negative PNA you are not locking in a trough over the east , and quite frankly I don’t see this changing though at least Christmas time .
So basically in summary , I expect a very volatile pattern, a lot of ups and downs , occasional cold fronts , overall averaging slightly above normal temperature wise from December 1st to December 15-20th with an overall quiet weather pattern, I just don’t see winter taking over in the forseeable future.
Pattern for first half of December: