Thunderstorm Wind — Mineral, Montana

2015-08-11 · near Borax, Mineral, Montana

Event narrative

A strong thunderstorm unleashed a small microburst that caused hundreds of trees to either snap in half or blow over at the Denna Mora Rest Area on Interstate 90 east of Lookout Pass. Two large fir and spruce trees with diameters up to 3 feet wide fell onto the eastbound lanes just to the northwest of the rest area obstructing the road at night. Approximately an hour later around 10 pm MDT, several vehicles hit the trees causing car damage, injuries and one fatality. A 21 year old male died after his vehicle collided with the topmost of the crisscrossed trees.

Wider weather episode

A cluster of thunderstorms developed at 3 pm MDT over Lemhi county and was associated with very frequent lightning strikes. This cluster of thunderstorms developed into a line and brought strong damaging winds to the Bitterroot and Missoula valleys. Numerous power lines were knocked down as a line of 60 mph winds push through the Bitterroot valley. As the thunderstorms approached Missoula, a macroburst developed and brought 74 mph wind gusts to the city of Missoula. Many power lines and trees were brought down and caused power outages for days in some areas.

View location on OpenStreetMap → (47.4196, -115.6288)

Source: NOAA Storm Events Database, event_id 624833. Narrative written by the NWS forecast office that issued the report.