With the mainly mild and quiet autumn we’ve had until this week, it’s natural to wonder if that will carry into the winter.
The dominant EPO+ weather pattern (persistent low pressures near Alaska) has maintained a strong zonal flow across North America, keeping the cold air locked up over Siberia.
I’m fond of saying “The snow pack doesn’t lie.” The gross lack of snow cover in southern Canada before this week’s snow event shows that most of the cold has been locked up over Siberia:
Notwithstanding the dominating EPO+ pattern we’ve had through much of autumn, I do believe there is hope we’ll bang out a decent winter here…certainly when you compare it to last winter. I think the secret sauce would have to involve a breakdown of the EPO+.
Let’s look at some key factors!
Siberian Snow Pack:
Groundbreaking study by Dr. Judah Cohen suggests a strong correlation between the spread of Siberian snow pack into Eurasia in October and how cold (and by implication, snowy) winter for the eastern United States.
The above table shows that October 2016 ranked #4 since 1968. That’s pretty impressive. Autumn snow cover spread was pretty impressive last year as well. But I think we can throw last year out the window the Super El Niño throwing everything out of whack, which leaves us with:
- #1: October 1976. This led into the legendary winter of 1976-77. I’m too young to remember that winter, so I’ll have to let some of the “old timers” tell you about that one. 😉
- #2: October 2014. The winter of 2014-15 wasn’t particularly notable for huge snowfall. But it was brutally cold at times, in which February 2015 was the coldest recorded month of all time for Indian Lake, for which records date back well over 100 years.
- #3: October 2002. The winter of 2002-03 was probably the best one from wire-to-wire that we’ve had in the last 20 years, certainly the best winter I’ve seen since running ilsnow.com: Consistent cold from start to finish and significant snows. Just when we thought we were done, we got clobbered with snow in April as well!
So, I think we have some good company…
Pacific Sea Surface temperatures
The warm PDO+ blob over the northeastern Pacific has been under attack by the howling Pacific jet. This causes upwelling of colder sub-surface waters to the surface. Since the warm PDO+ is tied into cold winters, that might appear to be a concern. But, this configuration still fits the definition of a warm PDO+.
We also have a weak La Niña in progress, shown by the cooler waters near the Equator. The ensembles cluster toward maintaining the weak La Niña through Winter 2016-17:
Strong La Niña can screw up winters as badly as strong El Niño. As long as we remain in weak La Niña or even edge up toward neutral ENSO, I think that could work in our favor.
Arctic Oscillation:
Negative Arctic Oscillation phase (AO-) is associated with higher pressure over the Arctic region which displaces cold air towards the United States. The implication being that a long term AO- brings a cold winter. Since early October, the AO has been mainly in the negative phase:
There has been a recent spike up to positive, but the ensembles quickly crash that back down for the second half of November. Granted, it has not been cold around here (largely due to the interference of EPO+). But, if the majority of the winter is spent under AO- and the EPO+ pattern dissolves, we can open the Siberian floodgates and get the cold air to our side of the North Pole.
Where do we go from here?
I’ve been feeding you the bad news on my YouTube channel and Facebook page for the past few months. The good news is that do I think the persistant EPO+ pattern will eventually break down. But the atmosphere has its work cut out before we can get to the good stuff!
December 2016
The CFSv2 model is showing a tendency for EPO+ induced fire hose Pacific Jet to split apart. When you split something, it becomes weaker. A weaker Pacific Jet would begin to favor ridging over western North America.
We may have some frustrating “two steps forward, one step backwards” weeks, but I believe December will move us toward where we want to be in 2017.
Verdict: Near Normal Temperatures – Near Normal Snowfall.
January 2017
This is starting to get fun! The EPO+ pattern over Alaska has been replaced by EPO- (higher pressures). The EPO- and PNA+ pattern over western North America opens up the cross polar flow and ushers the Siberian express into Canada with increasing regularity.
There is also some indication of an active storm track over the northern United States and a hint of Greenland blocking (NAO-).
Verdict: Below Normal Temperature – Near Normal to Above Normal Snowfall.
February 2017
February looks a lot like January, but even stormier and perhaps very cold!
Verdict: Below to Much Below Normal Temperature – Above Normal Snowfall.
Bottom line?
Please remember, the monthly panels are to give a general flavor only. The climate models have no ability to pick out individual events. Even in a cold, snowy month, you could get temporary pattern fluctuations that bring rain and warmth.
Assuming…
- AO- through majority of winter
- Weak La Nina / Neutral ENSO
- EPO+ pattern reverses to EPO-
- PDO+ holds though the winter
…I believe that December through February will average colder than normal with near to above average snowfall.
The biggest danger of issuing a winter outlook (aside from the fact it could be disastrously wrong) is that it could cloud up the forecaster’s ability to objectively look at what’s actually happening as time goes on.
For example: If I’m forecasting colder and snowier conditions for January but the EPO+ pattern isn’t letting up, I need to remain objective enough to see the data for what it is and forecast accordingly. I shouldn’t cling to a winter outlook that I issued months ago if the weather isn’t lining up.
So there you have it. I hope you enjoyed my analysis and look forward to a much strong winter than last year. 🙂
For the ilsnow nation,
Darrin
