Wyoming went more than 30 years without a tornado rated EF3/F3 or stronger but has now had three of them in less than two months.
The most recent EF3 tornado to hit Wyoming was last Saturday south of Douglas, a town of more than 16,000 in the east-central portion of the state. Two other EF3 tornadoes struck Wyoming in the first six days of June.
Saturday’s tornado was on the ground for 4.5 miles and had a maximum width of 350 yards, according to the National Weather Service preliminary survey (NWS). EF3 tornadoes have maximum estimated winds of 136 to 165 mph, making them capable of severe damage.
A ranch suffered the most significant damage from the tornado on Saturday, including several buildings that were destroyed and a house that had large sections of its roof removed. In addition, the NWS survey said two large trailers weighing several thousand pounds were sent flying and have yet to be located.
Wyoming’s two other EF3 tornadoes this year hit north of Laramie on June 6 and west-northwest of Gillette on June 1.
A storm chaser captured stunning video of the tornado near Laramie which scoured grass out of the ground along a portion of its path, an indication it had winds of EF3 strength.
The tornado near Gillette on June 1 injured two people and damaged numerous homes, buildings and vehicles.
EF3 Tornadoes Rare in Wyoming
Tornadoes are rated based on the damage they cause to structures or trees, not by how intense or large they appear visually.
Because many parts of Wyoming are rural, it can be difficult for the NWS to determine exactly how strong a tornado was if the twister remains over open areas with no structures or trees to damage.
But EF3/F3-rated tornadoes are rare in Wyoming. Only nine have been recorded in the state before this year, according to records dating back to 1950.
The last tornado to hit Wyoming before 2018 with estimated winds EF3/F3 or stronger was 31 years ago. An F4 tornado tore through Teton County to the east of Jackson on July 21, 1987, causing $2.5 million in damage.
The tornado near Douglas on Saturday was the first EF3/F3 to hit Converse County in 68 years of records, according to NOAA’s storm data. Just one tornado of F2 intensity has hit the county in that time.
Wyoming’s two other EF3-rated tornadoes from this year were the first for Albany County and Campbell County since records began in 1950.
An unusual number of tornado warnings have also been posted in Wyoming this year. Through July 30, the NWS had issued 51 tornado warnings in different parts of the state.
That’s well above Wyoming’s average over the past decade of 19 tornado warnings per year.
by Chris Dolce (2018, August 1) The Weather Company
