Updated: Rare winter thunderstorm, gale force winds rip through Driftless area

Wild winter weather brewed up wind and rain Wednesday, Dec. 15, as near-record high temperatures met an impending cold front that caused an over 35-degree drop in temperatures and high wind gusts up to 70 mph in the Driftless region.

By Connor Hopkins and Kate Klimesh

Update 12/21/21: More tornados confirmed 
Heavy storms throughout the Driftless Wednesday Dec. 15, brought Minnesota’s first ever winter tornado, and several spotted in Iowa as well. He crews from the National Weather service were busy over the weekend assessing the wide swath of areas hit by the storm from Kansas through Wisconsin. 
At this time, there have been several tornados confirmed in the Driftless region by the National Weather Service. Floyd County in Iowa saw two tornados clocking 110 piles per hour wind, Chickasaw County’s single confirmed tornado in Elma clocked winds topping 85 mph. Howard County saw two tornados in Schley and Maple Leaf also at 85 mph.  The Des Moines area saw 11 confirmed tornados.
In Minnesota, Racine had an EF-1 tornado confirmed, as did Fillmore county with Carrolton, Arendahl and Rushford Village, while EF-0 tornados touched down in Sumner and Preston. Three EF-1 and one EF-) confirmed tornados were listed in Wabasha, Houston and Winona counties in Minn., and the Twin Cities area in Minnesota saw five confirmed tornados, marking a total of 14 tornados confirmed in Minnesota from the Dec. 15th storm. 
There were hundreds of storm reports during this time noting wind speeds of 48 to 82 mph across the region. The National Weather Service has officially classified the line of storms on Dec. 15 as a derecho, the first ever recorded in December. According to the National Weather Service overview of the event, “A low pressure system of historic strength led to a variety of high-end weather impacts from the central plains to the Upper Midwest and Great Lakes December 15-16. An unprecedented December severe weather unfolded over portions of Minnesota and Wisconsin Wednesday evening, with the Storm Prediction Center issuing their farthest-north Moderate Risk for the Month of December. A serial derecho moving at 60-70 mph tracked from Kansas to Wisconsin, resulting in over 400 reports of damaging wind and several tornadoes. “
Near record high temperatures quickly fell below freezing across western and central Minnesota Wednesday night, causing rain to change over to a wintry mix of freezing drizzle and snow. Snowfall accumulations of 1-4″ inches, along with the strong gusty winds, led to low visibility and travel hazards late Wednesday night into Thursday morning.”

 

12/17/21: Rare winter thunderstorm, gale force winds rip through Driftless area
Wild winter weather brewed up wind and rain Wednesday, Dec. 15, as near-record high temperatures met an impending cold front that caused an over 35-degree drop in temperatures and high wind gusts up to 70 mph in the Driftless region. Winds caused damage to property across the area with severe weather warnings and watches in effect through 11 p.m. Wednesday evening.
Decorah’s resident weather authority, Richard Bernatz, noted, “This was the perfect storm. The extended, sustained duration of the storm, as well as the massive area over several states impacted by this very rare combination of a summertime and wintertime storm features makes it an extremely rare occurrence.”
The line of severe thunderstorms was fueled by the unseasonably warm, moist air that gave us 67 degrees Wednesday, met with not only a cold air mass coming over the whole Midwest, but a very low-pressure system as well. Bernatz noted that having the low-pressure system move in with fast upper-level winds created downdrafts that gave significant energy to push down and maintain high straight-line winds on the ground as the front moved across several states.
Bernatz noted the National Weather Service saw severe weather developing and issued severe thunderstorm warnings and damaging wind warnings as the front, with its associated bow-echo feature, moved eastward Wednesday.
“Frontal boundaries, where warm and cold air clash, commonly trigger thunderstorm development along and ahead of the front in our warmer months. The individual thunderstorm cells may combine to form a unified downdraft that creates a long stretch of straight-line winds – sometimes resulting in an event known as a ‘derecho.’ In Wednesday’s event, the strength of the ‘wintertime’ low with its fast-moving upper-level winds amplified the strength of the ‘summertime’ downdraft winds. The frontal structure created an environment where new thunderstorm cells continually develop along the front which allow winds to persist much longer in distance as well as length of time,” Bernatz reported. “The bow echo segment of the front is where the strongest winds occur. Variation in horizontal wind speed along the front can cause ‘spin-up’ tornadoes. Generally, this type of twister is not as severe as a tornado that develops with supercellular thunderstorms in the heat of the summer.”
He continued, “If this storm was over the Gulf of Mexico, it could be classified as a Category 1 hurricane. Since it was over land with more friction, it didn’t have the sustained wind speeds associated with a Category 1 hurricane but maintained persistent straight-line winds as it moved across several states.”

Outages and damages
Areas began to lose power at approximately 6 p.m. Wednesday. That evening saw power outages occur in Winneshiek, Allamakee, Howard, Fillmore and Houston Counties, with more than 19,240 outages reported across Iowa and southern Minnesota. Crews began working as soon as it was safe to do so Wednesday evening, and found downed electric transmission poles and equipment failures due to lightning strikes, high wind and tree damage. This resulted in the mass interruption of electric service for various towns.
Corey Snitker, Emergency Management Coordinator for Allamakee County, noted that things were less severe in his portion of the state. Beginning at 7:30 p.m., some residents of Waukon, Waterville and rural Allamakee County lost power, but only for approximately five hours compared to the 19 hours without power experienced in Decorah. In Lansing, power was only down for a few minutes. Snitker said that customers of Alliant are the ones who lost power for the longest, whereas customers of the Allamakee Clayton REC kept their lights on.
With wind gusts in the 50-mph range, there was slight damage in the area; Snitker noted a few trees down, damaged roofs, lost shingles, but ultimately “nothing all too serious.” As the storm front blew through around 8 p.m., Snitker said, “the derecho [of 2020] was the closest thing I’ve seen like this.” Yet, Snitker was relieved to say “this could’ve been a lot worse. This ended up being about as good as it could be.”
However, residents of Minnesota were not as fortunate. The storm brought Minnesota’s first ever December tornado, with twisters touching down and confirmed in Wyattville, Minn., approximately 40 miles east of Rochester. In Iowa, tornadoes were confirmed in Rudd, Elma, Maple Leaf, Schley and Marble Rock. At press time, National Weather Service representatives were still on the ground, assessing damage and determining the final status of tornadoes throughout the region.
Funnel clouds were spotted in Minnesota near Harmony at 7:45 p.m. Wednesday evening with wind gusts near 84 mph, reaching Mabel by 8:02 p.m. and Winona by 8:08 p.m. along the Mississippi River, but no confirmed touchdown. Wind gusts between 48 and 65 mph and tree and property damage were reported to the National Weather Service across the area through 9:14 p.m., with the last report from Grand Meadow, Minn., reporting significant roof damage to the CHS Inc. building from 83 mph winds.
In speaking with Brenda Tesch, Director of Public Relations for MiEnergy Cooperative, it was revealed that their service experienced approximately 7,500 outages because of the storm. By 5 a.m. Friday, that number was down to 400. By noon that day, it was down to 200. Tesch said, “Our crews left their regular work shift Wednesday afternoon, and by 6 p.m. that night they were being called back in.” According to the MiEnergy Facebook page, the Coop crews worked for 24 hours getting power back online for the service, which operates in Minnesota and Iowa. 
MiEnergy reported that they had “35 broken poles and counting” along with seven downed substations, as a result of the high winds and felled trees. Tesch stated the strategy for line crews is to “try and get the big stuff first,” meaning the substations. Each substation can provide power to anywhere from several hundred to a thousand services, which is the explainer for the massive outage. Once the substations are fixed, the power lines are the next priority. MiEnergy provided maps of outages on their Facebook page as progress was made, illustrating the widespread damage of the front.
Fillmore County Emergency Management Coordinator Don Kullot noted that Fillmore County experienced widespread outages Wednesday evening for around five hours following the storms. On Friday, Kullot was awaiting damage assessments from the National Weather Service team to determine if a tornado came through Fillmore County. “There was a significant amount of rural property damage from this storm. Preston was the hardest hit and had large trees taken down, power lines downed and roofs taken off.”  
Kullot reported power had been restored for most of the county, with sporadic outages still in effect Friday. MiEnergy, Dairyland Power and ITC had been working on repairs from storm damage, and were able to make some temporary connections to restore power. “The trouble with a wide-spread event is the shortage of poles available to fix the infrastructure damaged from the storms. Small poles cost around $2,000, while the large H poles that power communities are around $20,000.” 
However, the long-term fix to install new poles where damage occurred could be ongoing as supplies are available. With the storm raging along an estimated 100-mile front, many communities will be needing the same equipment, parts and poles to permanently replace damage to the infrastructure.  
Alliant Energy Community Development Manager Mike Wagner noted they were working with ITC as a transmission partner to get the feed back up and operational for areas still experiencing outages.  
The reason Decorah’s power outage lasted so long is in part due to the rural location of many power lines used by Alliant between Waukon and Decorah. “We knew the transmission lines were damaged and visually patrolled the line Wednesday evening as long as they could but had to wait for daylight to inspect lines crossing rural farm fields. Once they were able to find the damaged line, they found an alternate feed to use to bring power in. Then there was an equipment issue at the substation which required repair. Alliant had to take the city of Waukon offline to repair the substation, then powered the alternate feed and brought power in shortly before 2 p.m. – almost 2 hours ahead of schedule,” reported Wagner.
With continued outages, the Decorah community set up a warming shelter, including Decorah with the Decorah Area Food Pantry at the Spectrum building. Winneshiek County Emergency Management worked with RSVP volunteers Deb Tekippe and Carol Hemesath to set up an area where the public could stop in and stay warm with the power outages lasting around 19 hours Wednesday evening into Thursday, Dec. 15 and 16. Power was restored in the Decorah area shortly before 3 p.m. Thursday. 

Disaster proclamation
Gov. Kim Reynolds issued a disaster proclamation Thursday, Dec. 16 for 49 Iowa counties in response to the storms. The governor’s proclamation allows state resources to be utilized to respond to and recover from the effects of this severe weather and activates the Iowa Individual Assistance Grant Program for qualifying residents, along with the Disaster Case Management Program, for the following counties: 
Allamakee, Appanoose, Audubon, Bremer, Buena Vista, Butler, Calhoun, Cass, Cerro Gordo, Cherokee, Chickasaw, Davis, Emmet, Fayette, Floyd, Franklin, Greene, Guthrie, Hamilton, Hancock, Hardin, Harrison, Howard, Humboldt, Ida, Kossuth, Lucas, Madison, Marshall, Mills, Mitchell, Monroe, Montgomery, O’Brien, Page, Palo Alto, Pocahontas, Pottawattamie, Ringgold, Sac, Shelby, Union, Washington, Webster, Winnebago, Winneshiek, Woodbury, Worth and Wright counties.  
The Iowa Individual Assistance Grant Program provides grants of up to $5,000 for households with incomes up to 200 percent of the federal poverty level for home or car repairs, replacement of clothing or food and temporary housing expenses. Grant applications and instructions are available on the Iowa Department of Human Services website at https://dhs.iowa.gov/disaster-assistance-programs. Potential applicants have 45 days from the date of the proclamation to submit a claim.
 The Disaster Case Management Program addresses serious needs related to disaster-related hardship, injury, or adverse conditions, and case managers work with clients to create a disaster recovery plan and provide guidance, advice and referral to obtain a service or resource. For information on the Disaster Case Management Program, contact your local community action association or visit www.iowacommunityaction.org. 
 Residents of counties impacted by the recent severe weather are asked to report damage to help local and state officials better understand the damage sustained. Damage to property, roads, utilities and other storm-related information may be reported. This information will be collected by the Iowa Department of Homeland Security and Emergency Management and shared with local emergency management agencies. Damage may be reported at www.homelandsecurity.iowa.gov or call 1-800-972-2017.

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