During the afternoon of May 30th a line of thunderstorms moved south to north along the east slopes of the Cascades. These storms produced isolated damage from the Wenatchee area to the Methow Valley as they traveled north and eventually dissipated during the evening.
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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 afternoon of May 30th a line of thunderstorms moved south to north along the east slopes of the Cascades. These storms produced isolated damage from the Wenatchee area to the Methow Valley as they traveled north and eventually dissipated during the evening.
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 May 30, 4:04 PM PST, 46 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 504 PM PDT Tue May 30 2017 .SYNOPSIS... Thunderstorms move into the region tonight ahead of a cold front that will bring strong gusty winds and a good chance of showers and thunderstorms. Rises on rivers from the Cascades into north Idaho will continue due to warm conditions. By Wednesday and for the rest of the week, expect near seasonal temperatures, breezy winds and a chance of showers and thunderstorms in the higher terrain. && .DISCUSSION... ...GUSTY WIND WITH THUNDERSTORMS ACROSS CENTRAL AND EASTERN WASHINGTON TONIGHT... Tonight through Wednesday evening...Temperatures expected to peak today, the hottest days so far this year with changes on the way. A cold front passage will result in gusty wind and scattered thunderstorm activity tonight. Most short term models are hinting at disturbances associated with the frontal passage producing convection by utilizing the considerable instability and moisture available this evening and overnight (reflected in 700-500mb lapse rates near 8 deg C/Km along with precipitable water values increasing to near 200 percent of normal). 0-6km AGL average winds suggest a storm motion from south to north at 25 mph for storms that occur tonight. The resulting loss of the ridge and the substantial cooling brought about by the cold front passage will allow for a considerably cooler Wednesday. The flow pattern still favors a southwest flow with precipitable water values still running fairly high at just under an inch coupled with some pockets of moderate 700- 500mb lapse rates near 7 deg C/Km which is enough to keep a mention of convection, in the form of thunderstorms, mentioned for Wednesday and Wednesday evening. The storm motion has slightly more southwest to northeast orientation to it with a similar speed of near 25 mph. /Pelatti Wednesday night through Friday...The recent dry and warm weather shows no sign of returning during this period. Most of the Inland NW will be subject to the presence moist and unstable southwesterly flow associated with a deep upper level trough parked in the Gulf of Alaska. The threat of precipitation will be greatest Wednesday evening and again on Thursday afternoon as a pair of shortwave troughs pivot northeast on the front side of the offshore trough. The best overall moisture and potential instability will remain focused over the ID Panhandle, as well as over the eastern quarter of Washington and this is where we would expect to see the greatest chance of precipitation. The instability is also great enough to result in thunderstorms during these periods as well. The overall shear profiles and instability do not look extraordinary so the potential for anything other than general thunderstorms looks minimal. For Friday the jet axis begins to buckle northward in response to the deepening of the trough offshore. This should nudge the greatest threat of precipitation into the northern portions of the forecast area with only a small chance of thunderstorms near the Canadian border. Friday night through Saturday...there is good model consensus that the aforementioned jet will continue to buckle northward into BC which should result in a dry day for the region. By late Saturday through Sunday night the temporary drying will come to an end as a deeper trough and cold front pushes east of the Cascades. Temperatures through the week will return to normal values for this time of year and then become slightly warmer for Saturday. This means highs will begin in the upper 60s to mid 70s for most of the workweek warming into the mid 70s to mid 80s for Saturday. By Sunday they will cool once again as the deep trough and cold front moves into the region. fx Monday and Tuesday: Models begin to diverge on the specifics of how the upper low eventually exits the region. There is more agreement (GFS/EC) in a continued cool and showery pattern, in which the low will get hung up over Idaho and becoming cutoff, spinning in virtually the same spot. This will mean continued shower and thunderstorm chances over Idaho and eastern Washington Monday and Tuesday before the low finally exits by mid week. Under the low's influence high temperatures will be back to near normal, in the 70s. /bw && .AVIATION... ...GUST FRONT TO PROPAGATE AHEAD OF THUNDERSTORMS MOVING INTO WASHINGTON STATE LATE THIS AFTERNOON INTO THIS EVENING... 00Z TAFS: Scattered thunderstorms moving into southern WA late this afternoon out of northeast Oregon. There is good potential for strong outflow winds to be produced from these thunderstorms and will be capable of propagating far away from parent thunderstorms. Wind gusts may reach as strong as 40 kts across the basin with the best potential for strong winds at the KMWH TAF site. Winds may also pick up dust and blow it around that reduces vis at KMWH. Thunderstorms and gusty winds will reach KEAT by 02Z. There is less of a chance for thunderstorms at KGEG, KSFF, KCOE, KPUW and KLWS, but gusty westerly will be possible between 04-07Z. /SVH && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 71 54 70 51 70 / 40 20 20 50 20 20 Coeur d'Alene 56 73 52 69 50 69 / 30 30 30 60 30 20 Pullman 56 68 53 69 49 68 / 20 20 40 50 20 10 Lewiston 60 76 57 74 53 75 / 30 20 50 60 20 10 Colville 59 75 53 71 50 70 / 40 40 30 60 30 30 Sandpoint 54 74 49 68 46 67 / 20 30 50 60 40 30 Kellogg 52 75 48 66 45 66 / 10 30 60 70 30 20 Moses Lake 58 77 54 77 51 77 / 50 10 10 20 10 0 Wenatchee 57 74 57 73 54 73 / 50 10 10 20 10 10 Omak 59 75 53 75 51 74 / 50 40 10 30 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None &&
Hazardous Weather Outlook National Weather Service Spokane WA 1205 PM PDT Tue May 30 2017 IDZ002>004-026-027-WAZ031>036-041-044-311915- 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- WASHINGTON PALOUSE-MOSES LAKE AREA-UPPER COLUMBIA BASIN- SPOKANE AREA-WENATCHEE AREA-WATERVILLE PLATEAU- 1205 PM PDT Tue May 30 2017 This Hazardous Weather Outlook is for portions of North Idaho... North Central Idaho...Central Washington...East Central Washington...North Central Washington...Northeast Washington and Southeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT A cold front passage will result in a chance of thunderstorms. Some of these thunderstorms could produce locally heavy downpours, gusty winds and hail. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY The rest of the workweek will be cooler and continued unsettled with some chances of thunderstorms. IDZ001-WAZ037-038-042-043-311915- NORTHERN PANHANDLE-NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS- EAST SLOPES NORTHERN CASCADES-OKANOGAN VALLEY- 1205 PM PDT Tue May 30 2017 This Hazardous Weather Outlook is for portions of North Idaho... North Central Washington and Northeast Washington. .DAY ONE...THIS AFTERNOON AND TONIGHT A cold front passage will result in a chance of thunderstorms. Some of these thunderstorms could produce locally heavy downpours, gusty winds and hail. In addition increased snowmelt will continue or allow additional rises on area rivers and streams. Localized mainstem river flooding is possible near the Cascades. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY Increased snowmelt will allow for continued or additional rises on area rivers and streams. Localized mainstem river flooding is possible. Otherwise the rest of the workweek will be cooler and continued unsettled with some chances of thunderstorms.
The Seattle radar (KATX), 186 km away, was scanning. The volume nearest the first event began at 00:50 UTC.
3 thunderstorm wind. Local standard time, as filed.
A thunderstorm wind gust lofted a glass table top and shattered it near East Wenatchee.
The remote weather observing station at Entiat recorded a thunderstorm wind gust of 62 mph.
A thunderstorm wind gust toppled a tree onto power lines near Twisp. A power outage resulted from this damage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2017Every state in 2017This day in weather historyWarnings in Washington, May 2017
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: 699539, 699541, 699543.