Thursday Morning: We Got the Cold Coming, But How About a Storm?

Good morning once again everyone. We have talked a lot about this very impressive cold shot coming into our region next week. For those of you who have not checked in, you can find my breakdown in my last three posts. Today I want to focus on if I see any significant storm threats on the horizon. The nature of the post will be more speculative since we will be looking past the 5 day period, but I want to explain my thoughts. It will be fun to see if any of them pan out. 

Lets start off by taking a look at the middle of next week with our arriving cold shot.

A few things I highlighted. First, we can see the big press of arctic air due to a peice of the polar vortex sitting over southern Canada. Secondly, south of this cold barrier we have warmer air. The boundry between warm and cold air creates something called a "baroclinic zone". A baroclinic zone favors the development of low pressure systems due to the warm and cold air trying to balance each other out. Of course the mere boundary of air alone does not cause a storm, you need a disturbance to "spin up the air" and create waves of low pressure. The european model is hinting at a wave of low pressure developing along this zone on Wednesday as seen below off the nj coast..

I honestly do not know if this will be the exact scenerio but the potential is there because of that baroclinic zone. Last winter we saw a few moderate snow events from this type of set up. It is not out of the question given the cold air in place for us to see a few flakes middle of next week from a set up like this.

Let's now turn to what I think can be a bigger storm threat later next week into the weekend (14th-16th). I have been keeping my eye on this period for a few reasons. Remember that typhoon that was curving past japan in Monday's post? Well it is in the process of doing so right now and that is the first clue for unsettled weather 6-10 days from now. That brings us to my target zone of later next week into the weekend.  As a reminder the typhoon rule states that a typhoon recurving past japan can cause a trough to form over the eastern US 6-10 days later due to its effects on amplifying the jet stream. 

So about that jet stream, what will it look like from the middle of next week on?

What are are seeing above is the second factor that concerns me. The jet stream is splitting just off of the west coast. What does that mean? Basically one piece drives up into Canada and pulls the cold air down to the east coast as seen by the first yellow line and the second piece opens up the door for pacific moisture to flow into the country. Combine the unseasonably cold air and pacific moisture over the east coast and yeah you get my point. 

The models are showing a lot of disturbances in both of those streams by the time we get to later next week..

So will they combine to form a big storm? Impossible to say because we are over a week away and the margin for error on these models is huge! However, lets take a look at my third clue- the North Atlantic Oscillation (NAO). The NAO will be in its negative phase (high pressure over Greenland and Western Atlantic turns storms up the coast. You can see a diagram of its negative phase below..

Its not so much that we have a negative NAO late next week but the fact that the NAO will be transitioning from negative to more neutral. Why does this matter? Well research by two winter weather pioneers Paul Kocin and Louis Uccellini suggests that many big east coast storms form when the NAO is in this type of a transition. 

So as you guys can see I am building up evidence to support my case here for a potential storm. The models are starting to sniff it out as well..Image below is for next Sat

In Summary:

• Very cold pattern underway next week
• The barrier between warm and cold air can create opportunites for waves of low pressure to develop
• later in the period we need to be on the lookout for a big storm
• Factors behind this threat are
• cold air in place
• jet stream split
• typhoon rule
• NAO transition

I WILL END OFF BY SAYING THIS IS NOT GUARANTEED AND IS PURE SPECULATION THIS FAR OUT. THE GOAL IS TO JUST SHOW YOU GUYS HOW ALL THESE MOVING PARTS CAN COME TOGETHER IN THE MOST PERFECT OF CIRCUMSTANCES AND YES PRODUCE SNOW

Thanks for checking in.