Extreme Temperature Diary- Saturday December 19th, 2020/ Main Topic: More On How Climate Change Affects Winter Storms

The main purpose of this ongoing blog will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: More On How Climate Change Affects Winter Storms

Dear Diary. This week we had a historic winter storm, dubbed “Gail” by The Weather Channel, bury large sections of the Northeast with 30+ inches of snow. Throughout the history of the Northeast, while not occurring every year, such winter storms have happened since American Colonial Days in the 1600’s. Offhand, there was not much atypical about Gail except for the falling rate of heavy snow in some areas, so how did climate change affect this system, if any?

Since I’ve begun blogging on climate and weather in 2017 attribution of global warming to affecting winter storms is perhaps the hardest nut to crack as far as general weather goes. Here are a couple of examples I’d like for you to read from some earlier winter storms that I covered:

The 2018 post pertains to nor’easters, which is very much related to this week’s storm.

The New York Times also dealt with the question of how much climate change affected Gail. Here is their brief writeup:

How climate change is affecting winter storms.

By John Schwartz

Traffic and snow along the Vine Street Expressway in Philadelphia on Wednesday. Credit…Cameron Pollack for The New York Times

The major winter storm that hit the Eastern United States on Wednesday and Thursday probably prompted some people to ask, “What happened to global warming?”

But although it’s becoming increasingly clear that climate change does have an effect on storms, the relationship can be complex and, yes, counterintuitive. “There were these expectations that winter was basically going to disappear on us,” said Judah Cohen, director of seasonal forecasting at AER, a company that provides information to clients about weather and climate-related risk.

Although winters are becoming warmer and somewhat milder over all, extreme weather events have also been on the increase, and especially in the Northeastern United States, as Dr. Cohen pointed out in a recent paper in the journal Nature Climate Change. From the winter of 2008-9 until 2017-18, there were 27 major Northeast winter storms, three to four times the totals for each of the previous five decades.

One of the factors potentially feeding storms is a warmer atmosphere, which can hold more water vapor; not only can that mean more precipitation, but when the vapor forms clouds, “it releases heat into the air, which provides fuel for storms,” said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center. Also potentially important, but less understood, she noted, is “the increased tendency for the jet stream to take big swoops north and south,” setting up weather phenomena like the dreaded polar vortex.

Does that mean this particular storm has been fueled by climate change? Jonathan E. Martin, a professor in the department of atmospheric and oceanic sciences at the University of Wisconsin-Madison, cautioned against drawing quick conclusions.

Because of the “enormous natural variability” in storms and the weather they deliver, “I think it is a dangerous business attributing individual winter storms, or characteristics of them, to climate change,” he said. And this storm in particular, he added, is getting a lot of its moisture from water vapor evaporated off the Atlantic Ocean, which complicates the picture.

Dr. Francis agreed that any connections are complex, but added, “all storms now form in a greatly altered climate, so there’s little doubt that the same storm decades ago would not be the same.”

John Schwartz is a reporter on the climate desk. In nearly two decades at The Times, he has also covered science, law and technology. @jswatz • Facebook

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Here is a summation of what I know pertaining to how global warming is affecting winter storms:

1. Big “CAT 3” or worse winter storms are not getting less frequent yet. From what I can perceive there is a trend towards more winter storms bunched into years when the polar vortex is very wavy. Winters are warming overall, so there are more years in the United States, for example, with winter storm droughts such as in 2019 in the East. The net affect has been near zero for the 2010’s. Decades from now when the Northern Hemisphere has warmed enough to decimate the polar vortex and warm lower levels of the atmosphere to above freezing for minimums during the heart of winter at latitudes as far north as southern Canada, I would expect a rapid decrease in the number of winter storms.

2 Rising ocean heat is making nor’easters stronger as discussed in my 2018 post. Also, added heat in mid levels of the atmosphere can make inland storms deeper, causing stronger winds and higher snowfall amounts. Of course, a relatively warmer atmosphere holds more moisture and can aid to produce heavier snowfall.

3. The southern extent of areas around the planet where snow can fall is only now beginning to creep poleward. For example, winter storms are still possible as far south as the Gulf Coast and Florida Panhandle, but I doubt that we will ever see flurries as far south as Orlando and Tampa given our warming climate. Snow that far south was extremely rare during the cold decade of the 1970s anyway, so any perceptible changes are quite subtle.

I’ll be posting more on this topic as we move through the Northern Hemisphere winter of 2020/21.

Here is more climate and weather news from Saturday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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