Monday Morning Weather Discussion: Winter Knocking on Our Door

Good morning, I hope everyone enjoyed my winter outlook. We are going to stay on a similar theme today as the weather pattern has really come alive in recent days and shows more signs of life in the coming weeks. The mountains of New England got their first snowfall of the season over the weekend with areas like Jay Peak, VT receiving a foot plus of snow! Believe it or not, more snow is on the way to the mountain areas later this week as a potent clipper system move through the area. 

Here is a summary:

• Cold air enters region today through Wednesday. High temps will struggle to get into the high 50's for many spots with lows approaching freezing in northwest counties.

• A potent clipper system enters on the heals of this cold air causing some snow to break out initially in north central PA and southern NY State. The mountains of New England get another moderate snowfall from this.

• Moving to the long range, all signs point to a cooler than normal November

• This is supported by a very early season warming of the stratosphere that is about to occur. 

To set the stage, cold air builds back into the region today through Wednesday with Wednesday being the coldest. Expect temperatures to be in the 50's in most spots and possibly not breach 50 in northwestern counties on Wednesday. The image below shows this injection of air from the north..

Notice the arrows coming down from the north showing a north to northwest flow of cold air into the whole area. On the heals of this cold air mass, we have a low pressure system (clipper) that is going to approach from the west on Wednesday night and Thursday. The initial burst of precipitation can be snow for areas of north central PA and southern NY State. Northwest NJ might squeeze out a flake or two but I am not sold on that idea yet. The mountains of New England receive another moderate snowfall from this.

You can see the initial projections of precip on the GFS model..

Model is showing how cold air tries to hang in there initially. As the cold air departs the southern zones, the focus then becomes the mountains..

We will have to keep a close eye on the dynamics between how long the cold air holds on vs the strength of this system. If this system ends up being modeled a little deeper than cold air can hold on longer.

In any event, here is an idea of snowfall. Just focus on the spotty areas as I do not expect much of any accumulation outside of the mountains. I do not think that the low level terrain sees accumulations at this point. The model is prob overdoing those areas. 

In any event, we can all see winter is around the corner. This brings me to my next point..the stratosphere.

We are currently about to witness a very rare event in the stratosphere for this time of year. Models are projecting a stratospheric warming event which will largely displace or even split the polar vortex over the next week or so. I can not emphasize how rare it is to see that happen so early and I believe it will have big impacts on our weather from mid November on (2 to 3 week lag in response in the troposphere).

To make a long story short, when the stratosphere or upper levels of the atmosphere warm, it puts stress on the polar vortex. This stress weakens the polar vortex which allows cold air to spill into lower latitudes. On the flip side, when the polar vortex is strong the cold air stays locked up north. Looking below we can see what the GFS model is showing way way up in the atmosphere (much higher than planes fly)..

This shows temperature/pressure patterns. Notice the area of warm invading the poll and causing the vortex to almost split into two separate lobes. We usually do not see this happen until January or Feb or sometimes does not happen at all depending on the winter. What does it mean? Well, if we in fact do get the vortex to come under this stress then attacks of arctic air will be frequent from mid November on. 

Really interesting stuff. 

The models are starting to hint at this as well as we enter November..

Remember it is not January of February so a cold outbreak is not as intense. However, I think this November will be much different than last year in terms of temps and storminess. 

Thanks for reading.