An upper level trough moved from southwest Oregon on the morning of August 25th to southern British Columbia by the morning of the 26th. This system initiated strong thunderstorms on the evening of the 25th and also during the early morning hours on the 26th. These storms produced gusty winds that caused trees to topple over causing power outages and vehicle damage across portions of northwest Montana.

Thunderstorm Wind in LAKE, MONTANA
From 25-AUG-13 19:23:00 to 25-AUG-13 19:23:00 (MST-7)
Location: ROLLINS
Magnitude: 43.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter from Woods Bay reported power outages with at least one tree snapped in half.

Thunderstorm Wind in LAKE, MONTANA
From 25-AUG-13 19:25:00 to 25-AUG-13 19:25:00 (MST-7)
Location: DAYTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A NWS employee reported trees bending with one large tree blown down. The waves on Flathead lake were the highest she had ever seen.

Thunderstorm Wind in MINERAL, MONTANA
From 26-AUG-13 01:50:00 to 26-AUG-13 01:50:00 (MST-7)
Location: FORAKER
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

The Camels Hump lookout reported a measured wind gust to 58 mph during the early morning hours of August 26th.

Thunderstorm Wind in FLATHEAD, MONTANA
From 25-AUG-13 19:26:00 to 25-AUG-13 19:26:00 (MST-7)
Location: (FCA)KALISPELL INTL
Magnitude: 48.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

The Kalispell ASOS station measured a strong southerly wind gust to 55 mph.  The Flathead Valley power companies reported that around 5,000 customers lost power from 8pm MDT through the early morning hours on August 26. Multiple trees fell on power lines causing the outages.

Thunderstorm Wind in SANDERS, MONTANA
From 26-AUG-13 01:00:00 to 26-AUG-13 02:00:00 (MST-7)
Location: THOMPSON FALLS
Magnitude: 48.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Public

A member of the public reported a strong thunderstorm with heavy rain, lightning gusty winds that moved through between 2 and 3 am MDT. They received 0.75 total rainfall measured.

Thunderstorm Wind in FLATHEAD, MONTANA
From 26-AUG-13 19:26:00 to 26-AUG-13 19:26:00 (MST-7)
Location: KALISPELL
Magnitude: 48.00 MG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Newspaper

An 80-foot-tall pine tree fell over on 5th Ave West in Kalispell crushing a Corvette and damaging a truck, car and a boat.

Thunderstorm Wind in FLATHEAD, MONTANA
From 25-AUG-13 19:15:00 to 25-AUG-13 19:15:00 (MST-7)
Location: EVERGREEN
Magnitude: 40.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Newspaper

Downed power lines caused power outages and temporarily blocked U.S. 2 in Evergreen Sunday night.

Thunderstorm Wind in FLATHEAD, MONTANA
From 25-AUG-13 19:15:00 to 25-AUG-13 20:00:00 (MST-7)
Location: CRESTON
Magnitude: 40.00 MG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

A member of the public measured strong gusty winds that pushed over three large Ponderosa Pine trees and power outages.  A tree fell onto a transmission line that impacted two power substations causing power outages for the Many Lakes and Echo Lake area.

Thunderstorm Wind in SANDERS, MONTANA
From 26-AUG-13 01:30:00 to 26-AUG-13 02:30:00 (MST-7)
Location: THOMPSON FALLS
Magnitude: 48.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that the power was out from 0230 to 0645 hrs MDT on August 26th.