Extreme Temperature Diary- Tuesday March 16th, 2021/ Main Topic: Review Of Winter Storm Xylia…What Weather/Climate Change Threat Is Next For The U.S.?

The main purpose of this ongoing blog will be to track planetary 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).😉

Review Of Winter Storm Xylia…What Weather/Climate Change Threat Is Next For The U.S.?

Dear Diary. Weather models were spot on forecasting that Winter Storm Xylia would be a record breaker for portions of Colorado and Wyoming. Although somewhat of a stretch, there are two climate change tie ins to Xylia, the Weather Channel’s name for the storm. The first would be amplification of the 500 millibar pattern in association with a weakening polar vortex, and the second is due to an overall warming atmosphere that holds more moisture, in which winter storms can wring out higher quantities of snow than their 20th century counterparts.

As stated, both of these factors are a stretch since climatologically March is Denver’s snowiest month, and there has been precident for heavy past historic snowstorms like Xylia in the central Rockies. In this day and age sometimes as meteorologists and climatologists we are too quick to pull the trigger on blaming every large storm on climate change, even though each at least is subtly affected by an ever warming Earth.

Xylia was not a multi billion dollar destructive weather event because feared flooding from the central Plains into other portions of the Midwest did not materialize. The next potential disaster will be from spring storms that will rake across typical areas of the southern U.S. the rest of this month. Systems will dig into the central and southern Rockies and move eastward through the Plains as the overall jet stream weather pattern will remain unchanged the next couple of weeks. While strong, it would appear that none of these spring systems will be unprecedented.

The first could produce damaging tornadoes from Wednesday into Friday morning.

Be prepared for a deadly weather game of darts. One cluster of tornadoes moving directly over a moderate sized city could cause over a billion dollars in damage. Most likely, though, tornadoes will hit rural areas, thus each system would not likely prove to be extremely deadly except for unlucky folks that get hit.

Here is Bob’s review of Xylia, writing for the Washington Post:


Capital Weather Gang

Colorado and Wyoming see record blizzard, historic snowfall in Denver and Cheyenne

Drew Carey clears snow from the walkway of his home as a snowstorm rips across the intermountain West Sunday in Denver. (David Zalubowski/AP)

By Bob Henson March 15, 2021 at 7:17 a.m. PDT

A widespread, late-season snowstorm laid siege to parts of Colorado, Wyoming, Nebraska and South Dakota on Saturday and Sunday, dumping snow measured in feet in some areas and setting historic snowfall marks in two state capitals

As of 5 a.m. Monday, Cheyenne, Wyo., had received 30.8 inches of snow in the storm, with drifts as high as four feet. The snowfall topped the city’s previous record of 25.2 inches for any two-day period and 25.6 inches for any three-day period, both set in November 1979.

Denver International Airport (DIA), the city’s official weather-observation site, recorded 27.1 inches of wind-driven snow on Saturday and Sunday. This ranks as the largest two-calendar-day snowstorm on record for Denver (though larger two-day totals have fallen in more prolonged storms, such as the mammoth 37.4 inches recorded on December 4 to 5 in 1913 within a five-day marathon that produced 45.7 inches). It’s also the largest three-day total since 2003.

Interstates and major highways were closed across the region over the weekend, and many schools and businesses will remain shuttered on Monday. More than 2,300 flights were canceled on Saturday and Sunday at DIA, where all runways were closed throughout Sunday afternoon and evening.

Peña Boulevard, the main highway from the city to DIA, was reported to be “impassable” with multiple disabled vehicles.

On Monday, DIA’s runways remain closed with all morning flights canceled.

Blizzard warnings were in place starting Friday night from southeast Wyoming to the Black Hills of South Dakota. Cheyenne recorded 11 straight hours of gusts topping 40 mph amid the heavy snow through Sunday afternoon, meeting the criteria for a blizzard.

A winter storm warning was upgraded to a blizzard warning Sunday afternoon across the Colorado Front Range, including Denver. Winds were gusting to 46 mph in heavy snow at Rocky Mountain Metropolitan Airport, just northwest of Denver.

Satellite view of the storm over the Rockies and Plains Sunday. (NOAA)

Heavy spring snows are not unusual in the Central High Plains and the Front Range of the Rockies, including the eastern foothills as well as the adjacent urban corridor that runs along Interstate 25 from Pueblo, Colo., to Cheyenne. The region’s high elevation means that it is often still cold enough to snow when energetic spring weather systems pass through.

What made this event distinctive was the especially heavy snow totals along the northern half of the urban corridor, the result of a sprawling upper-level low-pressure system that was unusually slow-moving. Enormous amounts of moisture were squeezed out as easterly winds rotated around the northern side of this storm system and were forced upslope (pushed against the foothills).

The northern Front Range foothills of Colorado hit the snow jackpot, with totals as of late Sunday that included 40 inches near Red Feather Lakes and 36 inches near Nederland. Though impressive on their own, these totals paled next to the mind-boggling amounts of 60- to 80-plus inches recorded in some of the same areas during a similar spring storm in March 2003.

The weekend storm was a late bloomer for the Colorado Front Range. Forecasters and models had initially targeted the period from Friday night to Sunday morning, and strong dynamics had kicked off heavy snow in Wyoming by Saturday. However, a slug of drier air at upper levels mixed into the circulation across eastern Colorado, helping lead to a sporadic start with pockets of wet, showery snow and leaving some observers skeptical about the storm’s potential.

Upper-level winds didn’t push upslope through a deep layer until Sunday, when the storm’s back end proved to be a steady, prodigious snowmaker.

The plus side of an intense snowstorm: Drought relief

The arrival of moisture from the heavy snow was excellent news for a region afflicted by drought that has been steadily intensifying across the western half of the United States.

The storm will provide relatively little drought relief for western Colorado, including the Colorado River headwaters, but the widespread moisture east of the Divide could make a real difference, including to the winter wheat crop now in the soil.

The blizzard’s impact was muted by its timing. Nearly all of it fell over the weekend — not to mention during a pandemic, when most people were already sticking close to home. Moreover, the dense, heavy snow arrived before the region’s spring leaf-out, and that reduced the impact on tree limbs and the knock-on effect on power lines.

A tree down in Fort Collins, Colo., from heavy, wet snow on Sunday. (Alistair Vierod) (Alistair Viero)

Still, the wet, clingy nature of the initial snowfall led to power outages that affected more than 40,000 customers in Colorado on Sunday, according to PowerOutage.us. “This type of snow is able to easily stick to objects like power lines and branches,” noted the NWS Boulder office in a tweet.

The avalanche risk was rated “high” across the Front Range by the Colorado Avalanche Information Center, with an avalanche warning in effect until Monday morning.

The weekend storm was well foreseen by long-range models, which portrayed a vast snowmaker traversing the region a week in advance. The blizzard was also amply hyped in social media, largely because of eye-popping snow projections from the American (GFS) long-range forecast model.

Overall, snowfall totals came in fairly close to consistent forecasts from the European (ECMWF) model. However, totals were far less than the record-burying amounts projected across the Colorado Front Range over multiple GFS runs. The current structure of the U.S. model, known as the GFS-FV3, went into operational use in 2019 after adjustments to address a known tendency toward excessive snowfall.

The latest operational version of the GFS-FV3, known as GFSv15, is scheduled to be replaced this month by the updated GFSv16. Forecasts from the GFSv16, which is already being run in experimental mode, were generally less extreme and more in line with the totals actually notched in this storm.

Early-season tornadoes pepper the western Plains

As it dumped snow in and near the Rockies, the massive upper-level storm also fueled instability and wind shear that led to a brief, concentrated outbreak of rotating supercell thunderstorms in the Texas Panhandle and adjacent South Plains on Saturday. The National Weather Service Storm Prediction Center (SPC) logged a preliminary total of 17 tornadoes. Several of the twisters were large and highly visible, and twin tornadoes from a single storm were photographed and videotaped south of Canyon, Tex., about 20 miles south of Amarillo.

The first of those twin tornadoes was rated an EF2 on the Enhanced Fujita Scale by the Weather Service office in Amarillo, while the second one struck the entrance to Palo Duro Canyon State Park, causing major damage to a cluster of recreational vehicles, according to the Amarillo Globe-News. Five hikers initially reported missing had all been located by later that evening, and no injuries were reported.

“Although there is substantial property damage in the area, we are incredibly blessed that no one was injured or killed in this storm,” said Randall County Sheriff Christopher Forbis.

It was uncommonly early in the season for such a dramatic tornado outbreak so far west, where low-level moisture for thunderstorms is typically scant until at least April. In the entire Weather Service storm database going back to 1950, only a handful of weak tornadoes have been recorded before the midpoint of March across the Texas Panhandle.

Tornadoes in sparsely populated West Texas can have lower EF ratings than one might expect should they fail to cause noteworthy damage, from which EF ratings are determined.

Two landspout-type tornadoes were reported on Sunday near the intersection of Kansas, Nebraska and Colorado.

The Weather Service’s Storm Prediction Center had flagged the Texas tornado threat early Saturday morning, placing the affected area under a moderate risk of severe weather (the second-highest threat level) with a chance of strong, long-track tornadoes.

Bob Henson is a meteorologist and journalist based in Boulder, Colo. His books include “The Thinking Person’s Guide to Climate Change” and “Weather on the Air: A History of Broadcast Meteorology.”

Here are some more recently confirmed “ET’s:”

Here is more climate and weather 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. 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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