Extreme Temperature Diary- December 4th , 2018/ Topic: Old Fashioned Winter Storms…How Long Will They Last?

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Tuesday December 4th… Dear Diary. The main purpose of this ongoing post 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)😊. 

Old Fashioned Winter Storms…How Long Will They Last?

Meteorological models have been consistently forecasting a significant ice and snow storm for interior portions of the U.S. South for the better part of a week valid for this coming weekend. I don’t have much doubt after perusing charts this morning that the Carolinas will see a whopper of a winter event by Sunday. The climate across the south-central and southeast U.S., while warming, has not changed enough to prevent “rare” winter events. I’d often and mistakenly say at The Weather Channel during the warm decade of the 2000s that it was now nearly impossible for snow to fall in my home town of Atlanta due to global warming. Due to jet stream amplification from time to time, though, I’ve been proven wrong, at least through 2018. Last December north and west Atlanta had a tremendous snowstorm with up to a foot falling early in the month across Cobb and Paulding counties. My question for this post is when will the atmosphere due to carbon pollution get so warm that rare winter events for southern climes worldwide end?

First, let’s briefly take a look at the coming storm from this morning’s GFS model:

Here we see a storm system with a surface low moving just north of the Gulf Coast and a strong “wedge” of below freezing polar air filtering from the Northeast into the Piedmont area of the Carolinas. I’ve seen this weather setup countless times over my lifetime since I was a boy during the 1960s. Since the superstorm or “Storm of the Century” in March 1993, though, at least in Atlanta we’ve seen fewer winter events, such as severe ice storms, and snows have become “wetter” events, or marginal rain/snows near 32F.

At 500 millibars here is the forecast setup for this coming storm:

There is nothing extraordinary here except for a suspect warm anomaly in Canada forcing cold heights that probably will become a closed, cold low over the Southeast by Monday. My question, which cannot be answered as of this time, is when systems won’t be split off from the main polar vortex, creating rare southern storms? Will global averages need to achieve +1.5C, +2.0C,  +390C above  preindustrial conditions or higher? Certainly we are still not seeing the end of southern snow and ice at +1.0C, and certainly not in more northern traditional ski resorts, although the trend for snow across the northern hemisphere is down.

During the 1970s and 80s I remember that Alabama had a ski resort called Cloudmont, which thrived during those colder decades, but sporadically is open during the winter these days due to a lack of enough cold weather to generate snow, which is one small sign of climate change. I suspect that other ski resorts, which depend on natural snow, are suffering also, but their is not that much talk of permanent closure. Sorry Allan, but it may be a couple of more decades at least before this rather alarmist tweet comes to fruition:

Nevertheless, looking at our best science trends are clear, and Allan’s wording in his tweet is correct: http://wxshift.com/climate-change/climate-indicators/snow-cover

Quoting Wxshift:

Since satellites started collecting data in the early 1970s, there has been a trend toward less summer snow cover in the Northern Hemisphere. While most people might think of the summer as beach time, snow still covers a wide swath of land in the northern stretches of the globe. But over the past 50 years, that snow cover has been receding from a peak of 10.28 million square miles set in 1979 to a record low 3.69 million square miles set in 2013. Spring snow cover is also on the decline and this reduced snow cover is consistent with rising temperatures driving increased snowmelt.

Like ice, snow has a high reflectivity, so a shorter snow season increases the amount of sunlight absorbed by the Earth’s surface. The earlier spring snowmelt thus exhibits a feedback relationship with rising temperatures, driving further temperature increases. Snowmelt also affects water supplies, and decreasing snowpack may decrease water supplies in areas around the world that rely on spring runoff. Although fall and winter snow cover has remained fairly consistent over the past 40 years, spring and summer snow cover is typically more important in influencing water supplies.

Check out the graphics on the Wxshift article and explainer video by Burnadette Woods Placky, as well, for a better visualization. When I see three or four consecutive winters of no flakes in Atlanta we will know that true winter climate change has happened. Until then, just expect most Southern on camera meteorologists to wince at reporting science since the thought of including climate segments, especially during a week like this when flakes are forecast to fly with a chance for ice to produce havoc. To end this post let me state that I can’t wait to see an OCM in the Atlanta area be brave enough to present counterintuitive material…come on people, just one.

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Here is some more weather and climate news from Tuesday:

 

(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.)

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The  Climate Guy

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