Knuckleball weather

The rain that washed over Anchorage Monday brought snow to the Chugach Mountains/Craig Medred photo

Siberia was colder than hell to start the week. Rain was falling in Anchorage, heavily at times, on Monday. And Judah Cohen, the guru of the polar vortex, says it all makes sense.

But first a shout out to Cohen for his scientific honesty in these pandemic times.

“There is a Yiddish saying that probably many of you are familiar with – “Mann Tracht, Un Gott Lacht” which means “Man Plans, and God Laughs,” he wrote in his Monday weather analysis. “This is not the blog that I had planned but the cold, hard reality is leaving me no choice. I did think that I had troposphere-stratosphere-troposphere/polar vortex (PV) weather coupling all figured out (this is of course an exaggeration – I think I know the broad strokes but the devil is in the details and there is a lot that I don’t know) and now Mother Nature serves up an event that I am unfamiliar with and struggling to understand and anticipate the implications for our weather.”

The event in question, to grossly over-simplify, is a wave of warm, planetary air soaring toward space in conjunction with a weakening polar vortex, the latter being the normal swirl of the atmosphere around the pole as the earth rotates.

As Cohen writes on his blog for the weather forecasting company AER, this so-called “wave activity flux (WAFz)” is supposed to stop when the vortex weakens. But it is now continuing “to remain active following the initial wind reversal in the polar stratosphere the first week of January and will remain active right through the end of the month.

“I do have the winter season daily WAFz for every winter going back to 1969. and I cannot find another example of active WAFz following a mid-winter warming.

“To just show how unprecedented this may be, there is the possibility of two separate mid-winter warmings this winter separated by about a week…,” Cohen writes. “There have been two mid-winter warmings in one winter before but usually they are separated by months and not a week or two.  As far as I know this has never happened before.”

Just when you think you’ve figured out the pitches Mother Nature is tossing, along comes that unpredictable knuckleball. 

Not only is the wave activity flux not behaving as expected at the moment, the polar vortex (PV) is in a state of what might simply be described as chaos.

“It is complicated and we are in unchartered waters (at least for me) with this PV disruption,” Cohen writes….”We have multiple PV splits and PV displacements. So what are the combined impacts that we should expect?”

Cohen is betting on a cold snap in the Eastern U.S., but admits this is more a gut feeling than anything. The polar vortex is, of course, famous in the East.

Frozen heartland

Normally, the vortex’s swirling, cyclonic rotation keeps cold, Arctic air trapped in the Arctic. When the vortex weakens, however, frigid air can gush south through the center of North America to freeze the central and eastern part of the country.

A weak PV was blamed for 21, cold-related deaths in the U.S. in early 2019.

After the vortex weakened last year, NBC News headlined, “May mayhem: Polar vortex bringing historic cold, bomb cyclone and snow to Northeast this weekend.”

Much of Alaska usually warms up when this happens. The normal pattern is that when cold air starts flowing south down the middle of North America, warm air over the Pacific Ocean starts pushing north into the 49th state.

This is the so-called “butterfly effect,” one of the defining elements of chaos theory which dictates that small changes in one place can set off chain reactions leading to big changes in other areas, and thus the popular notion that a butterfly flapping its wings in the Amazon can touch off a tornado in Texas though nothing is quite that simple or that predictable. 

Still, most everything that happens on the planet is connected in ways big and small and sometimes there are patterns to the connections that can aid predictions of future events. The entire business of weather forecasting is built on this idea.

Enter Siberia

While Anchorage temperatures that reached 39 degrees on Monday were sliding back below freezing on Tuesday with a more seasonable forecast of temperatures down into the teens by the weekend, Yakutsk , Russia – a community of about 240,000 people along the Lena River in Siberia – was 56 degrees below zero. 

And it wasn’t even the coldest place in Siberia.

Accuweather was reporting that the Monday temperature hit 73-degrees-below zero on Monday in Delyankir, a small community about 500 miles northeast of Yakutsk. Such temperatures are brutal.

Specially blended “Arctic diesel” fuel gels at 40 degrees below zero. Hot coffee thrown into the air instantly turns into an ice cloud of frozen crystals. At 55 degrees below, exposed skin can freeze in two minutes.

Siberia is seeing these sort of temperatures because of a weakening of the polar vortex north of Asia. And the cold air flowing out of the Russian Arctic into Asia is having much the same effect on Anchorage weather as the cold air flows through the middle of North America.

Warm Pacific air flows north and Anchorage warms up. Whether you love this or hate this depends on your view toward cold and snow in general.

Cohen, for his part, calls the Siberian chill “the most important outcome from this winter, a sign that ‘winter is healing’ (could) be observed cold temperatures in Siberia.  The PV disruption did what it is supposed to do – it made winter great again in Siberia.

“Asia is experiencing a much colder winter so far and based on the forecasts…that should continue for the foreseeable future.  I believe if you are playing the long game on winter this is the most important outcome this winter, more so than cold and snow in your backyard.

“I am frustrated by the lack of snow and cold the past month here in the Northeastern U.S., but I do believe that the longer-term prospects improved greatly for both with the winter temperature anomalies in Siberia. As I like to say, Siberia is the refrigerator of the northern hemisphere, and if the refrigerator breaks down permanently there are poor prospects for winter across the entire northern hemisphere going forward and that includes your and my backyard.”

What exactly that refrigerator will mean to coastal Alaska is harder to say. Alaska glaciologists have observed that climate change has increased winter precipitation in the state’s Cook Inlet region by more than 100 percent since the mid-19th century, and along the state’s coast there just a few degrees shift in temperature can determine whether that precipitation falls as rain or snow.

Given that January is historically the coldest month of the year in the state’s largest city, the odds are good – despite what happened earlier this week – that whatever precipitation falls will fall as snow.

Anchorage saw both on Monday. While it rained for much of the day at lower elevations, snow was falling in the Chugach Mountains above the city.





4 replies »

  1. Good for you all a little above 59*N, but ugly rain that attempts being snow on the hill here in Homer. You turned me onto this climate guy and I visit his site every week. That was a good score. Thanks for that.

    • monk,
      say it aint so,I used to live a few hundred yards away from mcneil canyon school, many’s the time Id ski out to Bald Mtn.Or drive to Olson Mtn ,Crossmans ridge area and ski under a full moon thru the meadows and power line rights of way.Generally it was perhaps 10 degrees lower than the lower bench area, made for great powder/hoare frost

  2. The ADN weather forecast has been very inaccurate this year, such that I asked someone yesterday a committee of Democrats recently took over.

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