I tried to get a video up for Tuesday, but the procedure to translate the screenshot capture into a video crashed twice. To spend so much time preparing the video and to have it go up in flames is not good use of my time.
So, I have decided to discontinue the weather videos until I can find a way to streamline the procedure. In many ways, writing is much easier. Just type the article, insert pictures and press “publish.” No muss, no fuss!
Without any further delay, here are 4 factors I’ll be looking at:
- Siberian snow cover, especially October
- Warm PDO+ in North Pacific
- El Niño, possible chinks in the armor
- Massive western United States drought
Siberian Snow Cover:
If you have followed ilsnow.com for the past couple of years, you have heard about the importance of the spread of snow cover from Siberia into Eurasia in October. Here is a schematic of how that works:
Basically, the large snow pack over Siberia reflects more sunlight into the stratosphere and weakens the polar vortex. This in turn allows the jet stream to buckle and drive cold air into the eastern United States, especially with PNA+ ridging over the western United States.
Incidentally, the stratospheric polar vortex is different than the polar vortices I usually talk about, which are lower in the atmosphere and have more direct control over the day-to-day weather.
Here is what the Siberian snow cover looked like a few days ago:
The purple shows areas where snow cover is ahead of climatological schedule. This explosion of snow cover over Siberia is a good sign that Siberia is cooling rapidly.
The following ensemble chart shows that snow cover will continue to build nicely in Siberia and the Canadian Arctic under their respective pieces of the polar vortex:
Dr. Judah Cohen is a pioneer behind the October Siberia snow cover connection, often accurately predicting cold winters for the eastern United States when many other long range forecasters did not. Here is a snapshot of why it’s important:
October 1976, 2002 and 2014. Most of us know what happened the following winters: brutal cold and good snow!
Warm PDO+
Remember that warm blob of water in the northeast Pacific that helped to drive our bitter cold last winter? It’s still there!
Yes, we have the strong El Niño this year. But I’ll deal with that shortly. Let me remind you of what a massive warm PDO+ can do by showing you what happened in February 2015:
The warm PDO+ augmented the PNA+ ridging over the western United States, force feeding bitter Siberian air masses over the eastern half of the United States. It’s a very straight forward teleconnection.
El Niño:
“Godzilla” El Niño will be blamed for everything this winter, even though it’s just one of several large scale circulations that will determine our weather.
Taking a closer look at the sea surface temperature anomalies shows an interesting feature:
Notice how the warmest anomalies are starting to shift away from the South American coast? That is a sign our present El Niño has already peaked and will not become quite as strong as the 1997-98 El Niño.
In fact, this ensemble forecast shows that El Niño has leveled off and will begin to decline this winter:
That could have big implications for this winter. A rapidly collapsing El Niño, combined with warm PDO+ and strong Siberian cold could result in a jailbreak severe cold outbreak as the winter progresses into the New Year. This wouldn’t be a firm outlook yet, as we have to see how these factors evolve going into the winter.
Western United States Drought:
The Palmer index shows a long term severe drought over the western United States:
That drought, combined with the warm PDO+ could reinforce the PNA+ ridging in the western United States. This is a vicious cycle for the good people out west that desperately need rain! But it would be good news for winter lovers here.
Notice how wet it has been in the central United States? That actually concerns me for early winter because that would favor a trough position in the central United States with the prevailing storm track to our west as winter tries to take hold.
However, as the cold gets stronger and deeper into the winter, the trough position would be suppressed southeastward and shunt the storm path closer to the coast.
Bottom Line:
I can’t really say what kind of winter to expect for sure until we see what happens for the remainder of this fall, but I believe we have a puncher’s chance for a good winter.
There are plenty of well polished videos out there saying that our winter is completely screwed out the gate solely based on El Niño. No mention of warm PDO+. No mention of October Siberian snow cover expansion. To me, that’s woefully incomplete information.
El Niño is NOT the only game on the planet.
For the ilsnow nation,
Darrin
PS. I haven’t mentioned the North Atlantic Oscillation because I believe this winter will be so heavily Pacific dominated. Last winter it got really cold without a sustained NAO-/Greenland blocking pattern.
