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121 mph winds recorded in Thursday storms may be Minnesota record

A powerful storm system that swept through the northern Red River Valley this week caused "extreme" damage in Donaldson, Minn., as winds well over 100 mph snapped power poles and tossed parts of the local grain elevator onto nearby U.S. Highway 75.

A powerful storm system that swept through the northern Red River Valley this week caused "extreme" damage in Donaldson, Minn., as winds well over 100 mph snapped power poles and tossed parts of the local grain elevator onto nearby U.S. Highway 75.

A National Weather Service damage team visited the small town, population 42, in southern Kittson County on Thursday to assess the aftermath of the storm that struck Donaldson shortly after 3 a.m. that morning.

Westerly winds as high as 121 mph were recorded about a mile west of the town -- winds so powerful that, if confirmed, would shatter the state's long-standing record of 110 mph measured in 1904 during a tornado in Minneapolis.

Greg Gust, a warning coordination meteorologist with the weather service, said officials need to verify the sensor - installed by the Minnesota Department of Transportation along Highway 11 - was properly calibrated before this one can be entered into the record books. A similar investigation was performed earlier this summer to confirm that Moorhead's 88 degree dew point temperature recorded July 19 broke Minnesota's former record of 86 degrees set in 2005.

If verified, Thursday morning's powerful winds in Donaldson would become the highest surface wind observation ever recorded in the state. But that doesn't mean this was the highest wind speed to ever hit Minnesota, he said.

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"We have other wind events across the area in which we've estimated winds at least that high or higher, especially with tornadoes," he said. "But generally you don't have too many wind sensors that survive those types of things."

That means even though the winds were likely stronger, there was no sensor measurement to verify the numbers.

Winds stronger than 121 mph have been recorded by sensors located much higher than the one near Donaldson, which is within 10 meters of the ground. But Gust said these higher sensors record higher speeds because they have more exposure to the wind.

Whether it's a record or not, Gust said the Donaldson area seems to have suffered the most extreme winds that Thursday's storm packed as it swept across northern North Dakota and northwestern Minnesota.

Two large steel bins and a horizontal transfer system were torn entirely from the grain elevator and tossed nearby, partially blocking Highway 75.

"Nearly all" of the community's trees were damaged, Gust said, and the winds toppled wooden power poles and damaged shingles, roofing and siding on most homes.

Three steel grain bins were torn off their foundations and blown into a field about 1 mile east of Donaldson. Three more bins were dented and partially removed from their foundations at the same farm yard.

Gust said the damage, both inside the tree-sheltered town of Donaldson and in wide-open rural areas nearby, seems to be near the high end of EF-1 scale winds.

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Another noteworthy fact is the Donaldson sensor measured 121 mph winds for 11 minutes, a "pretty extreme" duration of time compared to a tornado that would typically move through much faster, Gust said. But that's another detail that will need to be investigated in the coming days, he said.

The same storm system produced downburst winds of 60 to 75 mph across parts of western and central North Dakota on Wednesday evening before sweeping into the Red River Valley early Thursday.

It caused extensive damage in Grafton, N.D., as 64 mph winds swept through about 2:45 a.m. and toppled more than 50 trees. Falling trees damaged five homes and multiple vehicles. The gusts damaged the grain elevator, several commercial buildings and knocked down utility poles.

Thunderstorms dumped more than 2 inches of rain in some areas. Grand Forks recorded 1.69 inches of rain. Only Warsaw (1.7 inches) and Rolla (1.82 inches) recorded more rain in North Dakota.

The heaviest rain hit northwestern Minnesota, totaling 2.64 inches in Euclid, 2.08 inches in Warren and 1.97 inches at the Thief River Falls airport.

The Donaldson area experienced far less rain, somewhere between 0.6 and 0.8 inches, based on observations at nearby sites.

"But it was moving through there pretty fast, obviously," Gust said.

The Grand Forks Herald and the Duluth News Tribune are owned by Forum Communications.

Related Topics: WEATHER
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