The developing winter pattern.

I wanted to go into a bit more depth on all of this And show more data. But due to the government shutdown, a lot of the data sites are down. So this will have to do. Depending how long this government shut down last will determine when I can post next; It could be at least a few weeks before I'm able to post another winter update!

Global water temperatures as of 30 September, 2025

We still have all that warm water in the North Pacific. These very warm sea surface temperatures (SST s) stretch from Canada all the way over to Asia. This has been Causing ridgeing which is deflecting the Pacific jet to the north. With the northern jet further  north, than typical for this time of year. It has all the cold  locked up over the Arctic due to the stronger than average polar vortex. 

Over the last 4 or 5 years We've had very warm water temperatures across the North Pacific. Here is a composite of the last 4 years. Compared to the 20 year average.These SST anomalies are well above average.

When we compare this to the 2 meter surface temperatures across north America we see there's a lot of warming across all of Canada and 2⁄3 of the United States. This is the result of the same process that I talked about above. Where we have that northern jet further north due to the ridge setting up over the Aleutians. Which alters the jet stream pattern damming up the cold air to our north.

Over the last few weeks we've had persistent troughing sitting in a Gulf of Alaska. 

But currently we are going to have the troughing work its way East. As strong ridgeing sets up over the Gulf of Alaska.

This is going to weaken the Polar Vortex which will allow that cold air that's locked up over the arctic to drift down into the mid latitudes. You can see that process in these Stratophere Images.

All of this is going to lead to the pattern change that I talked about today in the daily weather briefing. 

Ice and snow extant:

The last couple weeks have been quite cold in Siberia into northern Alaska. The cold is allowing snow to build across Siberia. As of October 1st snow extent across Siberia is well above average. This is going to help build that land bridge for the cold to extend across the Bering Strait into North America. The summer melt season in the Arctic is over. We're now starting to grow back sea ice. Right now, the ice extent in the Bering Sea is at its highest extent compared to the last few years that we've seen at this point in the season.

At this point in the season, arctic sea ice extent is much closer to northern Alaska than it has been in several years. This is good news if you want to see a cold winter here in the Northeast.

With that ridge up into Alaska, Alaska will warm up. We're going to see the cold air that's been bottled up in the north slide down that ridge/trough axis. The cold is going to move into the northwestern US and the northern Rockies and then come east into the central and eastern parts of the United States. As I said in my earlier post today that looks to happen around October 15th. I expect to see a snowstorm develop in the northern Rockies October 12 through maybe October 14th. If this happens it means I have a very good handle on the current developing winter pattern. While here in the  Northeast we won't be seeing snow that early; but the stage is being set for what's going to happen down the road. While Alaska is going to see warming temperatures; it still looks to stay cold over Siberia. Which will continue to add to that snow allowing the ice to continue to expand. Which will orchestrate a better chance to build cold into Canada as well as the central and eastern United States as we move further into October.