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First ever December Derecho puts area on high alert
In the Driftless
December 2021 Derecho
According to the National Weather Service, the December 15 storm was a serial Derecho, a type of storm produced by thunderstorms with strong winds which bow outward. The August 2020 Derecho that blew across Iowa was a progressive Derecho, a type of storm fueled by a hot and moist environment with relatively strong winds.

DRIFTLESS - In breaking news, Tuesday, Bill Bunting, chief of forecast operations at the National Weather Service's Storm Prediction Center, said that the storm that impacted our area on Wednesday, Dec. 15, was the first December Derecho ever recorded in the United States.

After watching images of the devastation in Kentucky the week before, it was easy to see why local National Weather Service (NWS) and emergency managers went into high gear last week to warn citizens about a weather system heading their way.

Wind damage extending more than 240 miles with wind gusts of at least 58 mph along most of its length can be classified as a Derecho. 

Last week's storm was a serial Derecho, a type of storm produced by thunder-storms with strong winds which bow outward. The August 2020 Derecho that blew across Iowa was a progressive Derecho, a type of storm fueled by a hot and moist environment with relatively strong winds.

Across our local region, in front of a storm that put down 19 tornadoes in the region, and produced winds as high as 85 mile-per-hour, local emergency managers opened storm shelters in well-built public buildings. Residents were urged to make plans to get to a safe place, pack emergency kits, secure outdoor belongings, and prepare for possible power outages.

The event was preceded by unseasonably warm weather that many local citizens reported as “eerie, unsettling, and creepy.”

Boulder, Colorado, meteorologist and journalist Bob Henson reported that at least two states set December records, based on preliminary data:

• Wisconsin: 72 degrees at Boscobel (old record 70 degrees at Kenosha and West Allis on December 5, 2001)

• Iowa:  78 degrees at Oskaloosa

The Des Moines Registerreported that NWS says there were 118 severe thunderstorm and 71 tornado warnings across Oklahoma, Kansas, Nebraska, Missouri, Wisconsin, Illinois and Iowa on the night of Wednesday,

Dec. 15.. 

Crawford County Director of Emergency Management Jim Hackett reported on storm impacts on Friday, Dec. 17:

 “In Crawford County we got very lucky.  Most of the villages and townships reported only trees down.  We did have a couple areas without power, but that was for a very short period of time.  We had 15 reports of outer building (sheds) damage, but there were no families with substantial loss.”

Emergency shelters were opened in Gays Mills and Wauzeka, and Hackett confirmed that several citizens had utilized the shelter in Gays Mills.

Vernon County Director of Emergency Management Brandon Larson had a similar report:

“In Vernon County we had several power lines go down across the county. I know there were at least 1,400 people without power for a time. There are some buildings that the roofs blew off, and at least one barn and a shed that blew down. In addition, a building in LaFarge lost some bricks off the side. The damages were all across the county, and the Viroqua Airport recorded a 69 mph wind gust around 9:15 p.m.” 

By noon on Thursday, Dec. 16, Vernon Electric Cooperative reported that they had restored power to “almost everyone affected.”

On Monday, Dec. 20, the Kickapoo Valley Reserve advised that field crews, along with some dedicated volunteers, are teaming up again to tackle the large number of trees down on the trails from last week’s wind storm. They advised that there would be heavy equipment and chainsaws in various places, and asked that hikers share reports of any downed trees on the property.

Ontario reported downed trees and scattered damage to siding and trees. A house fire broke out in Cashton in the early hours of Thursday, Dec. 16, and Cashton Fire & Rescue reported that continuing extreme winds complicated efforts to extinguish the fire. The home was extensively damaged, but no injuries resulted from the fire. The Westby-Christiana, Norwalk, Wilton, Ontario and Viroqua fire departments rendered mutual aid.

The Rotary Lights in LaCrosse were damaged, with several displays down and/or damaged. Thanks to extensive work by volunteer crews, the light display was back up and running by Friday, Dec. 17.

According to an article published in Up North News, “the storms and high winds came as the state experienced record-high temperatures for the month. Wisconsin should expect such weather as climate change results in abnormally high temperatures during winter months,’ Steve Vavrus, a senior scientist at the Nelson Institute Center for Climatic Research at UW-Madison, said.

 “Tornadoes don’t care what month it is. If you happen to have a warm, humid air mass below cold air and strong jet stream winds, like we’re having today, you’ve got the setup for severe weather, “ Vavrus said Wednesday afternoon.

Climate change?

In a piece penned the day after the storms, on Thursday, Dec. 16, Jeff Masters attempted to explain the difference between ‘climate’ and ‘weather,’ and how scientists would approach analysis of the December 10 and December 15 severe storms.

“Every weather event today plays out in a global atmosphere profoundly affected by human-produced greenhouse gases. Some types of extremes are more closely tied than others to the warming atmosphere.

“In the growing field of climate change attribution, researchers analyze a particular event and attempt to determine how much its likelihood was boosted (if at all) by human-caused cli-mate change. Two of the main outlets for attribution research are the ‘Explaining Extreme Events from a Climate Perspective’ series, in the ‘Bulletin of the American Meteorological Society,’and the ‘World Weather Attribution’ project.

“As discussed at this site in a recent ‘Climate Explained’ post, the links be-tween tornadoes and climate change are more nuanced than for phenomena such as heat waves or extreme rain-fall. Among the 40-plus ‘World Weather Attribution’ assessments and 150-plus ‘Explaining Extreme Events’ papers to date, not a single one has tried to connect the odds of a particular tornado outbreak to climate change – surely in part because tornado data is so fragmented, and because tornadoes are such rare, localized events.

‘It’s clear that the moist, record-warm air mass in place on December 10, assisted by record-warm temperatures for the time of year over the Gulf of Mexico, was essential for that day’s tornadoes. However, some of the other ingredients of high-end tornadic storms, such as a strong jet stream and strong vertical wind shear, do not necessarily intensify as the atmosphere warms (in fact, they’re often weaker during the hottest times of the year).

“All this helps explain why there’s been no long-term observed trend in the frequency of the most violent tornadoes. What scientists have found is growing variability – twisters clustered into larger outbreaks, with longer quiet periods in between – and also a multi-decadal shift in tornado-favorable environments from the Great Plains to-ward the Mississippi Valley and Mid-South.

‘Wednesday’s (Dec. 15) storm system might actually be a more tractable candidate for an attribution study than Friday’s (Dec. 10) tornado outbreak. For one thing, it was a larger-scale weather feature, something that’s more readily simulated within a regional or global computer model. Also, the sheer rarity of Wednesday’s varied weather features seems to be at least on par with the large-scale pattern of Friday’s tornado outbreak, perhaps even more exceptional (even though it wasn’t more destructive).

“We’ll see if any attribution research groups take up this challenge.”

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into Category 5 Hurricane Hugo, he left the Hurricane Hunters. In 1995, he co-founded the Weather Underground, and served as its chief meteorologist until it was sold in 2012. Between 2005-2019, his Category 6 blog was one of the Internet's most popular and widely quoted sources of extreme weather and climate change information.

Tornado reports

The NWS in La Crosse and Twin Cities have now confirmed 19 tornadoes occurred on December 15.

EF0: Elma, IA, 85 mph winds; Maple Leaf, IA, 85 mph winds: Schley, IA, 85 mph winds; Sumner, MN, 85 mph winds; Preston, MN, 80 mph winds; Wattville, MN, 85 mph winds; and Trempealeau, WI, 75 mph winds. 

EF1: Marble Rock, IA, 110 mph winds; Rudd, IA, 110 mph winds; Racine, MN, 110 mph winds; Carrolton, MN, 105 mph winds; Arendahl, MN, 95 mps winds; Rushford Village, MN, 90 mph winds; Money Creek, MN, 90 mph winds; Homer, MN, 100 mph winds; and Plainview Area, MN, 93 mph winds.

EF2: Five Mile Creek, WI, 130 mph winds; Christe, WI, 120 mph winds; and Stanley, WI, 120 mph winds.

Back to the west

John Barnick, meterologist for the Progressive Farmer, reported on the impacts where the storm began to intensify, just to the east of the Rocky Mountains:

“Just a couple of days after the Dec. 10 storm system, a trough of low pressure moved into the western U.S. where widespread precipitation helped to ease some of the drought, but also caused a multitude of winter weather advisories, storm warnings and high wind impacts. But the true strength of the system occurred after it crossed the Rocky Mountains.

“Temperatures out ahead of the system were once again very high. In fact, there were widespread records broken both for the day and the month of December from Texas all the way up to Wisconsin. In several of these instances, the records were completely smashed by 10 to 20 degrees. 

“For example, by rising up to 74 degrees Fahrenheit, Omaha, Nebraska, beat its all-time December high by just two degrees but smashed its daily record by 15 degrees. Waterloo, Iowa, is the most extreme example. By reaching a high of 74 degrees, it beat its all-time December record by seven degrees and its daily record by 20 degrees.

“Ahead of the system, winds were gusting on the order of 30 to 40 miles per hour (mph). That was not an atypical windy day in the Plains or western Midwest. However, as the system moved east of the Rockies, it rapidly strengthened and deepened, causing winds to rush even faster. Widespread wind gusts over 70 mph were recorded from Amarillo, Texas, up to Rap-id City, South Dakota, and then eastward through al-most all of Nebraska and Kansas, western Iowa and northwest Missouri. Other wind gusts exceeding 50 mph were recorded elsewhere throughout the Plains and the northwestern half of the Midwest.

“Winds in the Central Plains made for incredible video. Aided by the dryness and drought, dust was easily picked up by the strong winds and blown vast distances. During the after-noon, it was easily visible on satellite imagery. It will still need to be assessed whether the erosion caused significant damage to winter wheat in the region.

“Some of those wind gusts were aided by yet another round of severe December storms. In contrast to the severe event that unfolded in the Midwest and Midsouth five days earlier, severe storms occurred with one broken line.

Storms started to develop early in the afternoon across south-central Nebraska and north-central Kansas. The line expanded north and south as it moved rapidly northeast through the after-noon and evening hours. Extreme wind gusts and several tornadoes developed along the line.

Bob Henson reported that the winds in Kansas sparked wildfires:

“A few wildfires erupted, but it’s fortunate there were no pre-existing fire lines of any notable size that the wind could strike perpendicularly. Instead, the blazes that popped up were like strings of fire, stretched along the wind vector. One fire in Oldham County west of Amarillo, Texas, spanned 3,500 acres along a ribbon 14 miles long and just a half-mile wide.”

Donations to farmers

According to an article by Greg Henderson of Ag Web:

“In Russell County in central Kansas, wildfires burned into the night, prompting evacuations in Waldo, Paradise and Fairport, and destroying multiple homes. Crews in the town of Russell worked through the night to restore power.

“The wildfires prompted the Kansas Livestock Association (KLA) and other ag groups to begin coordinating donations of feed, fencing supplies and cash for affected ranchers. The bulk of the acres burned are within the counties of Russell, Osborne, Rooks and Ellis. Ranchers in the hardest hit areas lost fence, livestock and feed resources, the KLA said. Ranch homes and outbuildings also were among the losses. 

“Cash donations can be made through the Kansas Livestock Foundation (KLF), KLA’s charitable arm, by sending a check, with ‘wildfire relief’ written in the memo line, to 6031 S.W. 37th, Topeka, KS 66614. All proceeds will be used to help those affected by the recent weather event.  If you are in need of supplies or would like to make an in-kind donation, call KLA at 785-273-5115.”