During the late night and early morning hours of June 25th a strong cold front transited eastern Washington. The front exploited mid level instability and a moist air mass as it crossed the Cascades and broke out into eastern Washington. A line of thunderstorms developed between midnight and 4 AM PST and transited west to east through the Cascades and the mountains of northeastern Washington. Many of these storms were severe with damaging outflow winds blowing down trees, damaging structures and producing power outages in the Cascades and the Okanogan Highlands. Several fires were started by lightning strikes as well.  The line weakened as it moved through north Idaho with no further damage reports, and passed into Montana by 7 AM PST, ending further thunderstorm activity.
Many people confirmed this event's damage with pictures of buildings and hundreds of trees lost in small, localized areas.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 03:09:00 to 25-JUN-18 03:09:00 (PST-8)
Location: LOOMIS
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Aeneas RAWS station reported southwest winds of 37 mph sustained with a gust of 64 mph as a cold front passed through the region.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 02:40:00 to 25-JUN-18 02:40:00 (PST-8)
Location: OROVILLE
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Oroville RAWS station reported west winds of 17 mph sustained with a gust of 61 mph as a thunderstorm passed through during the morning of June 25th.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 01:50:00 to 25-JUN-18 01:50:00 (PST-8)
Location: METHOW
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Douglas Ingram Ridge RAWS station recorded a wind gust of 58 mph as thunderstorms moved through the area.

Thunderstorm Wind in CHELAN, WASHINGTON
From 25-JUN-18 01:30:00 to 25-JUN-18 01:30:00 (PST-8)
Location: ENTIAT
Magnitude: 60.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Entiat RAWS station reported a wind gust of 69 mph as thunderstorms moved through the area during the early morning of June 25th.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 01:25:00 to 25-JUN-18 01:35:00 (PST-8)
Location: TWISP
Magnitude: 56.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A tree was toppled onto a house in Twisp by a thunderstorm wind gust.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 01:00:00 to 25-JUN-18 02:00:00 (PST-8)
Location: MAZAMA
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees and power lines were toppled in the Mazama area due to thunderstorm wind gusts. At least 3 fires were reported to the emergency manager due to downed power lines in the Methow Valley.

Thunderstorm Wind in FERRY, WASHINGTON
From 25-JUN-18 03:20:00 to 25-JUN-18 03:40:00 (PST-8)
Location: REPUBLIC
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Department of Highways

The county highway department reported travel restrictions along Highway 20 due to  toppled trees and downed power lines west of Republic. A second report from a member of the public indicated about 100 trees toppled at and near this location from thunderstorm winds. Time of event estimated from radar.

Thunderstorm Wind in FERRY, WASHINGTON
From 25-JUN-18 03:20:00 to 25-JUN-18 03:40:00 (PST-8)
Location: REPUBLIC
Magnitude: 56.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: COOP Observer

An observer in Republic reported a power outage with trees on houses in Republic. Time of event was estimated from radar.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 02:15:00 to 25-JUN-18 02:30:00 (PST-8)
Location: (4OM)OMAK ARPT
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public reported a tree on a home near Omak.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 02:50:00 to 25-JUN-18 03:10:00 (PST-8)
Location: BODIE
Magnitude: 56.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

A member of the public posted photos on social media of numerous trees down at the Beaver Lake Campground near Chesaw. Time of event estimated from radar.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 01:50:00 to 25-JUN-18 02:20:00 (PST-8)
Location: PATEROS
Magnitude: 61.00 EG
Property damage: 70.00K
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorm winds downed numerous trees at Alta Lake State Park. At least 2 parked automobiles were damaged when large trees fell on them. Social media reports indicated 4 people were injured as trees fell within the campsites. Time of event estimated from radar.

Thunderstorm Wind in OKANOGAN, WASHINGTON
From 25-JUN-18 02:50:00 to 25-JUN-18 03:10:00 (PST-8)
Location: OLD TORODA
Magnitude: 65.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Public

A member of the public posted photos on social media of numerous trees down at Bonaparte Lake Resort. Time of event estimated from radar.

Thunderstorm Wind in DOUGLAS, WASHINGTON
From 25-JUN-18 02:10:00 to 25-JUN-18 02:20:00 (PST-8)
Location: BRIDGEPORT
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A member of the public posted photos of two large fir trees toppled in Bridgeport. A newspaper report indicated 680 customers lost power in Bridgeport. Time of event estimated from radar.