Posted: May 2, 2013 8:19 PM by STORMTracker Weather Team
Updated: May 2, 2013 8:20 PM
John Blank is the longest serving meteorologist at the National Weather Service office in Great Falls.
Since 1981, he's tracked some of the worst storms in the state's history.
He recalled, "Many years here, I hadn't really seen one hit a town until the Lewistown tornado. And, it did some damage in town."
That was August 14, 1999; the tornado created a five-mile long damage path.
Three people were injured and more than 150 homes were damaged or destroyed.
In 2010, a tornado struck Billings, taking the roof off the Metrapark; no one died, and only minor injuries were reported.
That same year, a tornado tore through Sheridan County tornado on July 26, killing two people and injuring another during its 18-mile long path (click here).
Its damage was rated as EF-3 strength, with estimated winds of between 136 mph and 165 mph.
At its largest point, it was a half mile wide and tossed debris as far away as Crosby, North Dakota; damage was estimated at nearly $300,000.
Only the Mineral County tornado of June 1923 ties for the most fatalities; it was rated F-1 with winds of 73-112 mph.
Blank said, "The main damage occurred at a ranch, but it was really pretty spectacular. Pretty much wiped out the house and surrounding buildings and threw a truck, I think about, a quarter of a mile."
Data from the past 62 years shows that most of Montana's tornadoes occur in the eastern part of the state, specifically Valley County.
Supercell storms, which produce tornadoes, require lots of low level moisture and wind shear, something our state sees only a few times each year.
More often, Montana sees severe hail and damaging winds.
Some of the largest hailstones collected under the Big Sky measured 5 to 6 inches, roughly the size of a softball.
Valley County also tops the list for the most hail events since 1950, followed closely behind by Yellowstone County, and when it comes to severe winds, the same counties are in a tie.
Damaging straight line winds can be just as destructive as tornadoes and can produce damage on a wider scale.