Thursday: Winter Storm Signal Showing on Models for a Week Out

Good morning. It was nice to see the first snowfall of the season yesterday for many. I recorded 1.3" in my backyard and the scene really made things feel like the holidays. 

Looking ahead, things will get milder for a few days with some showers Saturday night. In the wake of this however, a weather pattern is setting up for the second half of December that is the best I have seen on paper for this time of year in a while. No guarantees, but the potential is there for cold and snowfall in the Northeast.

The first period of focus will be a week out. Most major model suites are now showing a storm signal for later next week. Given that the pattern setup would support a storm, I am not taking this as a fluke. Nothing is guaranteed or locked in by any means but I have enough information that its worth discussing.

Fast forwarding to early next week, many models show a nice injection of cold air in the wake of our mild weekend...

This is a key ingredient as with any storm you need true cold air. We have something called the Tropospheric Polar vortex that is sitting in northern Canada which is aiding in sourcing this cold air.

Now the key is can we keep this cold air locked in ahead of a approaching storm system? At this time, models have been trending towards a pattern that can do this. The two key variables I look for is high pressure over Greenland and a low pressure system off the coast of eastern Canada (50/50 low). You can see below there are hints of this...

Why is this important. Well, when you get this pattern it tends to promote high pressure over eastern Canada and lock in cold air ahead of any approaching energy. You can see this below...

A pattern like this is so critical to see it snow near the big cities in the northeast and even near the I-95 corridor. This is the classic look for a storm that I look for.

At the surface models are showing storm development on Thursday, but as usual the track is uncertain as noted by the different low pressure symbols...

Do not take this next image literally as this will change dozens of times next several days, but if all these factors above came into alignment perfectly, you can see a scenario similar to this below...

Yes, that would be a major winter storm. You will literally see models at the surface loose the storm, move the storm inland, and out to sea next several days. Thats always how this game works.

However, if the key variables in my image stay on the map and trend in the right direction the storm potential will still be there. I will show the image again...

This is all we should be focusing on next several days. Surface projections mean nothing. I will say the bigger storms usually do show up earlier on the models for some reason. I do not know why but its an observation I have made over many years. 

Stay tuned, we may have a lot to be discussing next several days and weeks. Winter is here.