Tuesday, November 1, 2016

A recap and revised winter 2016-2017 outlook.

Just a quick update on the coming winter of 2016-2017.

Snow cover:


I've been talking a lot about snow cover, and how the greater the Eurasian snow cover grows from the 60 degree line south, during the month of October, the greater the likelihood for a cold winter in the East Coast CONUS.

Siberian Snow Cover extent.  is very impressive. You can see this year snow cover is 2nd only to 2014-2015, which was a very cold and snowy winter. You will notice that the snow growth in 2015 was close to this year. But if you remember, winter 2015-2016 was dominated by the Super El Nino, which was so strong it overrode all the other teleconnections. This year the other teleconnections will be in play. 

While I can find no real correlation between Canadian snow cover and East Coast winters.  You can see the extent of snow cover in Canada is notable. There is a lot of snow on the ground in Southeast Canada. This can only help, to keep the winter air mass over the northeast  colder.


The North Atlantic Oscillation (NAO) and  Arctic Oscillation (AO) are both in a negative phase right now.  So this is leading to blocking over eastern Canada and Greenland. Because of this these Canadian weather systems moving into the Northeast are much slower to depart. Therefore we tend to hang onto the cold longer. We will see this happen this coming weekend, as the Midwest and Mid Atlantic States heat up, while the Northeast stays a little cool.

The Southern Oscillation Index (SOI) is isolating back and forth. But it did jump start this pattern to a wintertime one.


Years that have weak La Nina's or have neutral conditions tend to be more prone to Greenland blocking.  So the Northeast sees more cold outbreaks, as well as a slowing down of the Clippers and Coastal storms, which helps the odds of seeing greater snow amounts.

I talk a lot about atmospheric patterns, and how they are cyclical in nature.  When a pattern looks similar to ones in the past, it is logical to expect a similar outcome.   The pattern we're now in  is similar to the 1950's into the 1960's.. I made my 2016 hurricane outlook based on analogs from the 50's and 60's.  So far I've nailed the hurricane season this year...  only missing out of a major hurricane CONUS landfall ( but to be fair, I only missed that one by a mere 12 miles).
If you look at my winter outlooks for 2016-2017 you will see that there are a lot of analog years from the 1950's and 1960's. In fact if you do a reanalysis of those years, you will see there is a striking similarity between this year's setup and those years.  you will also see how my thoughts have evolved and clarified. But overall, there hasn't been a lot of change from what I posted in September, or even before that on my Facebook Weather Page.

The northern hemisphere arctic is warm this year (as compared to average).  But years that had a lot of warmth in the arctic, tended to be cold, with lots of blocking.

I showed the other day, on my Facebook Weather Page, how the pattern is shaping up, with the trough in the Atlantic pulling west, the ridge over the East Coast  and the trough off the West Coast are also pulling west.  I said watch the trough in the Pacific Northwest, when it pulled west and deepened that was the sign that winter would begin.  All of that is currently in play.

The extent of cold in Eurasia is almost unprecedented. While the CONUS has been quite warm.  But that is about to change. The pattern change that has been occurring now for about a week, will continue.  The cold in Siberia will make its way into the Lower 48 by way of the northern jet.   I've been saying that I expect the current pattern change to be in place by the Middle of November; I see nothing that is changing my mind. In fact December could end up being very cold, very cold indeed. With the high likelihood of blocking in the North Atlantic, we have a shot at a few decent snow events between Thanksgiving and Christmas. I've been showing charts that show the Euro's long range ideas. The other day I made a chart that showed the typical La Nina storm tracks.  

The Euro long range control and mean are showing a lot of snow through Mid December.

I have very little doubt about how winter 2016-2017 is going to turn out.  It's going to be a colder and snowier winter here in the Northeast and Mid Atlantic States.  December looks to be very cold. All and all,  Northeast Maine and far eastern New England look to average out around normal.

The Great Lakes are very warm, for this time of year. So once we see more frequent cold outbreaks over the next few weeks, I expect to see lake effect snow falling across western, Upstate New York and western Pennsylvania.
Here are my updated temperature and snowfall ideas. For the snowfall outlook, I've added percentages to make it a true forecast. The snowfall is from first flake to last flake (including what we've already seen this month).