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.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS OTX wrote it up.
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.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at Jun 24, 9:58 PM PST, 3 hours 2 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 1058 PM PDT Sun Jun 24 2018 .SYNOPSIS... A strong cold front will bring the potential for overnight and early morning thunderstorms across northern Washington followed by gusty winds across portions of central and eastern Washington. The remainder of the week is expected to be cooler than average. Showers will be possible late in the week and into the weekend. && .DISCUSSION... ...GUSTY WINDS MONDAY ACROSS PORTIONS OF CENTRAL AND EASTERN WASHINGTON... Tonight...Afternoon mainly mountain cumulus will dissipate with the setting sun. Hope you were able to get out and enjoy the warm weather. Today was the warmest day for at least the next 7. A cold front is approaching the west coast this afternoon and will push over the Cascades towards midnight, and then quickly move through eastern WA and north ID. This is a mostly dry cold front. However the models do show a chance of precipitation across northern WA overnight. They are also showing elevated instability, and have kept the mention of thunderstorms overnight. Some parameters are showing such good instability in addition to the moisture and kicker that have increased our threat from isolated to scattered across the Okanogan Valley and mountains to the east towards Colville. The main threat will be from 2am till about 8 am with impacts of lightning and brief heavy rain. Temperatures overnight will be about 5-10 degrees above average given the cloud cover that will move in with and ahead of the front. Valley low temps in the low 60s is expected. Monday and Monday Night...The cold front will continue to quickly move out of the area in the morning. Showers and isolated thunderstorms will be possible along the Canadian border. Once the front passes, winds will increase from the southwest or west. Winds 15 to 25 mph with gusts to 35 is expected across the Wenatchee valley through the Waterville Plateau into the Columbia Basin, Palouse and Spokane area. Winds will peak in the mid to late afternoon with the exception of western Whitman Co, where their winds will peak during the morning. The winds will decrease with the setting sun. Skies will clear, and with drier air in place post cold front, overnight lows will feel chilly compared to the night before. Temps will be about 2-6 degrees below average, or valley temps in the mid 40s to around 50. Some typical cold pockets of 40 around Priest Lake, Republic, Deer Park, Cheney is possible. /Nisbet Tuesday and Wednesday: A zonal flow will set up in the region for this period behind the Low from Monday and bring a dry air mass into the region. A few isolated showers over the Cascades are possible. Winds will begin to decrease as the pressure gradient loosens and drops the winds into the single digits and low teens. Valleys in the Cascades could reach gusts of low 20s. Temperatures will be near normal with highs in the low 70s to low 80s. Thursday through Sunday: A change in the jet pattern from westerly to northwesterly is expected to bring a trof through the region being supported by a Low passing through Central BC. The models are in poor agreement on the entry and exit timing of the Low and the moisture associated with it. The impacts with this Low are expected to be mainly mountain rain showers with possible afternoon thunderstorms. The best threat of thunder is expected on Friday. Temperatures are still expected to be near normal with highs in the 70s to low 80s and lows in the 50s. /JDC && .Fire Weather... A mainly dry cold front will move through the fire districts overnight into Monday morning. Showers and thunderstorms are possible across the northern districts, with the main impact being lightning and brief heavy rain btwn 0200-0800 LST. Post cold front, the winds will increase and become breezy to windy. 15 to 25 mph winds with gusts to 35 mph is expected starting aft 12Z and will continue through the daylight hours. The kittitas Valley will see slightly stronger winds with gusts up to 40 mph. Relative humidities will be low, but not quite to any critical highlight worthy values. In addition, looking at the ERCs and 100 hr fuels, we are not even close to the 85th percentile. So, while we will see elevated fire concerns across our southern districts with the potential for any fire that starts to spread quickly because of the wind...we will not be issuing any highlights as our fuels are not to critical levels yet. /Nisbet && .AVIATION... 06Z TAFS: The cold front is marching toward the Cascades this evening bringing high clouds to the region first. Showers and isolated thunderstorms will spread over the northern mountains overnight toward Monday morning. The main impact for the TAF sites will be wind as a sharp increase in wind is expected Monday morning which will continue through the late afternoon hours. The 06Z TAF update includes minor tweaks to the wind speeds and diminishing the winds during the last 6 hours. No precipitation or significant ceilings are expected with this FROPA. Winds will remain breezy Monday night but continue to slowly diminish. /AB && .PRELIMINARY POINT TEMPS/POPS... Spokane 63 75 48 71 50 74 / 0 0 0 0 0 0 Coeur d'Alene 63 75 46 71 48 73 / 0 0 0 0 0 0 Pullman 61 72 45 70 48 73 / 0 0 0 0 0 0 Lewiston 63 80 53 77 54 82 / 0 0 0 0 0 0 Colville 60 78 46 75 46 75 / 40 40 0 0 0 0 Sandpoint 60 76 45 70 46 71 / 0 10 0 0 0 0 Kellogg 61 72 45 68 47 71 / 0 0 0 0 0 0 Moses Lake 62 78 48 78 51 79 / 0 0 0 0 0 0 Wenatchee 62 74 51 77 53 76 / 20 20 0 0 0 0 Omak 64 77 48 78 50 77 / 60 60 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
Hazardous Weather Outlook National Weather Service Spokane WA 327 PM PDT Sun Jun 24 2018 IDZ001-WAZ037-038-042-043-251400- Northern Panhandle-Northeast Mountains-Okanogan Highlands- East Slopes Northern Cascades-Okanogan Valley- 327 PM PDT Sun Jun 24 2018 This Hazardous Weather Outlook is for portions of North Idaho... North Central Washington and Northeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT Showers and thunderstorms are possible overnight into early Monday morning. The impact from these storms will be lightning and brief heavy rain. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY No hazardous weather is expected at this time. WAZ033>036-041-044-251400- Washington Palouse-Moses Lake Area-Upper Columbia Basin- Spokane Area-Wenatchee Area-Waterville Plateau- 327 PM PDT Sun Jun 24 2018 This Hazardous Weather Outlook is for portions of Central Washington...East Central Washington...North Central Washington... Northeast Washington and Southeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY Dry and windy conditions will develop Monday across the Columbia Basin into the Palouse and west plains. Relative humidities in the teens and lower 20s along with sustained winds of 15-25 mph will mean an enhanced risk of fire spread. IDZ002>004-026-027-WAZ031-032-251400- Coeur d'Alene Area-Idaho Palouse-Central Panhandle Mountains- Lewiston Area-Lewis and Southern Nez Perce Counties- Northeast Blue Mountains-Lower Garfield and Asotin Counties- 327 PM PDT Sun Jun 24 2018 This Hazardous Weather Outlook is for portions of North Idaho... North Central Idaho and Southeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY No hazardous weather is expected at this time.
The Seattle radar (KATX), 161 km away, was scanning. The volume nearest the first event began at 08:58 UTC.
13 thunderstorm wind. Local standard time, as filed.
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.
A tree was toppled onto a house in Twisp by a thunderstorm wind gust.
The Entiat RAWS station reported a wind gust of 69 mph as thunderstorms moved through the area during the early morning of June 25th.
The Douglas Ingram Ridge RAWS station recorded a wind gust of 58 mph as thunderstorms moved through the area.
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.
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.
A member of the public reported a tree on a home near Omak.
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.
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.
A member of the public posted photos on social media of numerous trees down at Bonaparte Lake Resort. Time of event estimated from radar.
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.
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.
An observer in Republic reported a power outage with trees on houses in Republic. Time of event was estimated from radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2018Every state in 2018This day in weather historyWarnings in Washington, June 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 762942, 762939, 762937, 762936, 762947, 762949, 762945, 762935, 762946, 762948, 762934, 762943, 762944.