Wednesday, March 5, 2014

What the Heck Was Wrong with this Winter?

For openers, before we dig into why it's been so cold in the Midwest this winter, let's take a look at what's really wrong with this winter around the world.  Here is a picture that Paul Douglas, Founder and CEO of WeatherNation, received from his great aunt, Eva Fels-Huber, in Cologne, Germany, along with her description of this winter in Western Europe:

"We are still waiting for winter to arrive.  We had spring-like temperatures since December 10th, 12C (53F) every day.  The birds are singing; my roses started blooming in mid-January." 

After Paul sent me this picture from his aunt, I sent an e-mail to a friend in Germany and asked her what their winter had been like this year.   Here is her response: 

“As for the winter here: we live between Mannheim and Heidelberg and didn't have winter at all. My sister in Bavaria said: some snow showers, that was it. Friends of ours in Eastern Germany said about the same. It is colder there than here, but no winter really.
In the middle of February I saw in Heidelberg meadows full of blooming daisies.  Now when you walk or drive around: everywhere daffodils and bushes and trees in yellow, white and pink.”

This is more the norm around the world than our cold weather in the Midwest.  Consider this statement from Paul Douglas' blog in the StarTribune:

"...Earth had its fourth warmest January.... According to NOAA, the combined average temperature over global land and ocean surfaces for January was 54.8 degrees Fahrenheit, which was 1.17 degrees above the 20th century average.  Using different analysis methods, NASA also concluded that Alaska had its third warmest January.... China had its second warmest January on record, and France tied with 1988 and 1936 for its warmest January."

Enter the Polar Vortex

So, tell that to gardeners in Minnesota and the whole Midwest.  If the earth is warmer than normal, how does that account for what seems to be one of the toughest winters in Midwest history? Here's a January 6th quote from Andrew Freedman of  the climate think-tank, Climate Central, that speaks to that question:

"Scientists said the deep freeze gripping the U.S. does not indicate a halt or reversal in global warming trends, either. In fact, it may be a counterintuitive example of global warming in action. Researchers told Climate Central that the weather pattern driving the extreme cold into the U.S. — with a weaker polar vortex moving around the Arctic like a slowing spinning top, eventually falling over and blowing open the door to the Arctic freezer — fits with other recently observed instances of unusual fall and wintertime jet stream configurations.

"Such weather patterns, which can feature relatively mild conditions in the Arctic at the same time dangerously cold conditions exist in vast parts of the lower 48, may be tied to the rapid warming and loss of sea ice in the Arctic due, in part, to man-made climate change.

"Arctic warming is altering the heat balance between the North Pole and the equator, which is what drives the strong current of upper level winds in the northern hemisphere commonly known as the jet stream. Some studies show that if that balance is altered then some types of extreme weather events become more likely to occur."

There is no question that the intrusion of the Polar Vortex is producing one of the worst winters in a long time for the Twin Cities and around the Midwest, including cities like Chicago, Detroit, Indianapolis and St. Louis. As a matter of fact, places like Detroit and Chicago have had worse winters, relatively speaking, than the Twin Cities. More about that later.  The real problem with the winter of 2013-2014, however, is not the depth of the cold, but the extent and continuity of it. We have currently had 50 below zero nights here and several more are predicted, which probably will put us in at least fourth and possibly third place, historically, for number of below zero nights in a winter season (the record is 60 in 1874-75, which we probably won't reach).

But it's important to note that we have had only one night this winter with USDA zone 4 cold.  It was -23 on January 6, 2014, which by no means was record cold for us.  In the 53 winters since 1962 the lowest temperature recorded has been -34 in 1970.  The rest of our below-zero temperatures this winter, despite how bad they felt, have been in zones 5 and 6.  Here's the breakdown: One below zero night in zone 4, 11 in zone 5, and the other 38 in zone 6.  So, while some people (especially some of  the TV weather people droning on about wind chills) would like to call this a record cold winter, it really isn't; it's just very long and miserable. And honestly it's wearing very thin with me, not unlike last winter, which was warmer, but also very long. Please read the conclusion of my blog: "How Winter Affects Roses" for my take on how an unreasonably long winter negatively affects roses:

People in Minnesota are so naturally self-effacing about winter that they tend to think this is happening only to them: "Uff Dah, it's why we tip our roses, don't ya know" Not! As noted above, we have had just one night in zone 4 (and just barely), considering that 12 of our winters since 2000 have been in zone 5.  With that in mind, let's take a look at how other Midwest cities have been affected.

  • Detroit and Ann Arbor, where I grew up and went to college, have almost always been in zone 6, in the lee of the Great Lakes. Since 2000, six of Detroit's winters have been in zone 7 (i.e. not even below zero) and the rest in zone 6. This winter, their low temperatures have been -14 and -12, i.e., two nights in zone 5; twelve nights in zone 6, and the rest in zone 7.

  • Chicago, which has had all but one of its winters in zone 6 or above since 2000, had a low of -16 in January, with a grand total of four nights in zone 5.  That's a bigger variance than either Detroit or the Twin Cities.

  • St. Louis, which has been in zone 7 every year since 2000, with one exception when it was in zone 8, saw a low of -8 this winter, with a total of four nights in zone 6; a big variance for them.

  • Indianapolis, which has had seven winters in zone 7 and five in zone 6, since 2000, saw two nights in zone 5 this year, with low temperatures of -15 and -14; another big variance.

The Polar Vortex 

So what exactly is the Polar Vortex?  Here is a good explanation from an NBC News piece from early January:

"The polar vortex is basically a great swirling pool of extremely cold air located tens of thousands of feet in the atmosphere.... Basically an arctic cyclone, it ordinarily spins counterclockwise around the north and south poles.  While it tends to dip over northeastern Canada, it's catching everyone's attention because it has moved southward over such a large population....Why has it traveled so far south? Chiefly, warmer air builds up over areas such as Greenland or Alaska and that air forces the colder, denser air southward.... "

And here is a statement that Paul Douglas prepared for this blog post:

" I remember some very cold winters in the mid and late 70s, but even then there was more variability in the jet stream, more fluctuations and mild periods in between arctic blasts. What is unique about this winter, in my opinion, is the persistence of this blocking pattern. We’ve gone nearly 3 months in a row with little variation in the jet stream over North America. This mirrors a larger (global) trend of slower jet stream winds over northern latitudes and more of a tendency for “blocking” patterns, where weather slows or even stalls for days or weeks at a time. Jennifer Francis at Rutgers has done some research on this “polar amplification”, theorizing that rapid warming of the Arctic and far northern latitudes is disrupting north-south temperature extremes, which, in turn, may be impacting jet stream winds, with more of a tendency for weather to become locked or “stuck”.

“ I've been tracking weather for over 40 years and I can’t remember a winter quite like this, the sheer persistence of the pattern to remain more or less stuck in place. Western drought, numbing cold east of the Rockies, with historic flooding for Britain and record warmth for much of Europe – it’s all interconnected. More research is required to confirm whether rapid warming in far northern latitudes (and summer ice melt in the Arctic) is, in fact, having a domino effect at our latitude, but with each passing year the weather is becoming more unusual, more extremes, more “weather-whiplash” (flood to drought, etc) and more volatility in general. I tell people the truth: we are changing the chemical composition of the atmosphere, conducting an experiment that’s never been done before. CO2 levels are at 400 ppm, higher than any time in the last 800,000 years. We’re poking at Earth’s climate system with a long, sharp stick and then acting surprised when the weather comes back to bite us.

Here are graphics that show the Polar Vortex incursion in the central U.S.  Note especially the warmer than normal zones in the Alaska and Greenland areas, which are responsible for pushing the jet stream and polar air southward:

The 64 trillion dollar question, so to speak, is whether this polar vortex incursion, caused by the unprecedented warming of the arctic regions, will reoccur in the years ahead.  There seems to be a fairly high probability that we will see it again but it seems to me that, as the earth continues to warm over the years, it may not be as extreme, i.e. the polar air will be warmer (not a good thing for the earth).  Consider again what Paul Douglas told us:

"... We are changing the chemical composition of the atmosphere, conducting an experiment that’s never been done before. CO2 levels are at 400 ppm, higher than any time in the last 800,000 years. We’re poking at Earth’s climate system with a long, sharp stick and then acting surprised when the weather comes back to bite us."

I am also a great believer in statistical trend lines, and the extreme minimum temperature (EMT) trend lines that I have plotted for almost all Midwest cities, for the years since 1962, show that we are all on a steady trend toward higher winter temperatures.  The Twin Cities' EMT trend line shows conclusively that we have moved into zone 5 and are on our way to zone 6 in just a few years.  One night of marginally zone 4 temperatures in 2014 certainly does not change the upward slope of our trend line in a meaningful way, so it is statistically reasonable to assume that we will continue to see warmer EMTs in the years ahead.

But, to use Paul's analogy, who knows what will happen when we poke the earth's climate system with a long, sharp stick?  My statistical prognostications for a warmer winter this year were certainly wrong and one of my good friends took the opportunity last week to give me a gentle push into a snow bank at Bredesen Park in Edina, as retribution.  Here is the Minnesota Rose Gardener making a snow angel in two feet of snow!

Finally, Twin Cities meteorologist, Jonathan Yuhas, (with tongue in cheek I'm sure) posted the following graphic on Facebook.  Notice any similarity to the polar vortex graphics above?  Oh well, smell the roses while we can; maybe sometime in July this year.

Jack Falker
March 5, 2014