Periodic heavy rain and spring-time snow melt during April and early May produced saturated soil conditions over northeast Washington. Even during dry periods scattered debris flows continued to occur in the mountainous regions of northeast Washington through May before soil conditions dried out.
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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.
Periodic heavy rain and spring-time snow melt during April and early May produced saturated soil conditions over northeast Washington. Even during dry periods scattered debris flows continued to occur in the mountainous regions of northeast Washington through May before soil conditions dried out.
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 19, 3:25 AM PST, 1 hour 35 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 425 AM PDT Fri May 19 2017 .SYNOPSIS... High pressure slowly builds over the Inland Northwest today yet there will be a small chance of mountain showers and a stray thunderstorm. Late tonight into Saturday, an potent upper level disturbance will bring a renewed threat of showers and thunderstorms for much of eastern Washington and the Idaho panhandle. Then Sunday into early next week, dry and warmer temperatures are expected under the ridge of high pressure and this may increase mountain snowmelt and lead to rises on local rivers and streams. There is the potential for cooler and unsettled weather by late in the week. && .DISCUSSION... Today through Saturday: The Inland NW will remain in northwest flow aloft and on the fringe of the building upper ridge. With the departing shortwave trough this morning, the upper ridge will gradually nose into the region. Plenty of mid and low level moisture remains with Pwats still above 0.5" across the region. Weak surface based instability will increase mainly across northeast Washington and north Idaho, with cape values near 200 j/kg and LIs around -1. Low level winds will be light and out of the southwest, aiding in upslope flow. Convection will develop and anticipate another round of showers with embedded thunderstorms by afternoon into early evening with the prime target area the northeast and Panhandle mountains. Meanwhile, temperatures will be on the rise, about 2-6 degrees warmer than yesterday with highs topping out in the mid 60s to near 80, which is normal for mid May. Convective clouds and showers will dissipate by mid evening, although high level clouds will increase from the northwest. The models are in agreement of a potent little shortwave rolling from Vancouver Island overnight and across the Inland NW on Saturday. The timing of this feature is slightly quicker and a bit to the west, which will give the region more cloud cover and a better chance of showers. In fact showers will increase late tonight near the Canadian border and spread across eastern Washington Saturday morning. The upper jet will dip south of the region while Pwats increase to over 0.75" along with good forcing seen in the potential vorticity. There is a little mid level instability that could lead to a stray thunderstorm for Saturday morning in the northern Panhandle. Although best chance for thunderstorms will be with the surface based instability that will increase by afternoon on the periphery of the cloud shield and shower band across extreme eastern Washington and north Idaho. Northerly winds will increase across north central Washington into the western Basin. Temperatures will be tricky given the cloud cover and could see highs similar if not a degree or two cooler for Saturday. This wave looks to be quick mover and exits the the region Saturday evening with drier conditions. /rfox. Saturday night through Sunday...Model consistency is good that the eastern third of the forecast area will remain on the cool side of the upper level jet in continued NW flow. The positioning of the jet combined with diurnal heating will keep the threat of showers and isolated thunderstorms continuing into early Saturday evening and again on Sunday afternoon. The chances of thunder Saturday evening will generally be over the eastern quarter of Washington and across the Idaho Panhandle. By Sunday that threat will largely be relegated to the Idaho Panhandle with the best chances south of the Silver Valley. Monday through Wednesday...Model consistency and hence forecast confidence remains high for this period as we see perhaps the strongest upper level ridge so far this year. 500 mb heights surge above 580 dm which should result in sunny and dry conditions. However the main feature will be a significant warming trend. High temperatures will steadily warm through this period, beginning with highs in the mid 70s to mid 80s on Monday and climbing into the 80s to lower 90s by Wednesday. This will result in considerable snow melt over all elevations as snow levels rise to 10k feet or higher. This will bring rises to all rivers fed by snowmelt across the northern portions of Washington and into the Cascades as the snowpack remains quite high for this time of year. Values as of this afternoon generally ranged from 130-170 percent of the seasonal normal. This should bring some of the rivers including the Okanogan, Stehekin, and the Kettle to minor flood stage by midweek. Just how long the flooding will last is questionable. That's because there is quite a bit of uncertainty as to how persistent the strong ridge will be. Wednesday evening through Friday...The EC has been consistent breaking the ridge down by Wednesday evening while the Canadian and previous GFS runs kept us quite warm and dry at least through Thursday. Now even the GFS is putting that notion in question as it nudges the ridge into western Montana by Thursday and leaves it there though Friday. The latest GFS not only nudges the ridge eastward it subjects the region to a very unstable day on Thursday with lesser amounts of potential instability on Friday. The 00z places a large area of MUCAPEs around 1500-2000 j/kg over the eastern third of Washington and north Idaho on Thursday with lesser amounts near the Cascades. Not sure how realistic this is as it is derived from surface dewpoints in the lower 60s which seems a little too moist. Also the dprog/dt on this is very poor. The EC solution for this period features a much deeper low centered over SW Canada and consequently has much cooler temperatures and less instability over the Inland NW. Based on how the weather has been for most of the year, we will hedge more toward the cooler and wetter solution. We will continue to blend the EC to the GFS for temperatures however if we went with a full EC we'd see highs in the upper 50s and 60s for this portion of the forecast. fx && .AVIATION... 12Z TAFS: Light winds aloft and a deck of mid level clouds will slowly move across the region this morning as the ridge amplifies. VFR conditions should remain at the TAF sites although patchy fog is possible in the northern valleys. After 20z, more convective clouds are likely along with spotty showers. Best chance will be northeast Washington and the ID panhandle and included VCSH in KCOE and KPUW. After 02z, clouds and showers should dissipate. High clouds will move in from the northwest overnight. /rfox. && .PRELIMINARY POINT TEMPS/POPS... Spokane 68 49 66 48 74 52 / 10 10 70 10 10 0 Coeur d'Alene 67 48 64 46 73 48 / 20 10 70 20 10 10 Pullman 67 45 63 46 72 48 / 10 0 50 20 10 10 Lewiston 73 49 71 49 77 53 / 10 0 50 30 10 10 Colville 69 49 69 48 76 49 / 20 40 70 20 10 0 Sandpoint 66 45 65 45 72 45 / 20 30 60 40 10 10 Kellogg 67 44 64 43 72 45 / 30 20 60 40 20 10 Moses Lake 75 52 75 51 82 54 / 0 10 20 0 0 0 Wenatchee 73 54 74 51 80 55 / 0 0 10 0 0 0 Omak 73 53 74 50 80 53 / 10 10 30 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
Hazardous Weather Outlook National Weather Service Spokane WA 120 AM PDT Fri May 19 2017 IDZ001-004-WAZ037-200830- NORTHERN PANHANDLE-CENTRAL PANHANDLE MOUNTAINS- NORTHEAST MOUNTAINS- 120 AM PDT Fri May 19 2017 This Hazardous Weather Outlook is for portions of North Idaho and Northeast Washington. .DAY ONE...TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY There is a chance for afternoon thunderstorms Saturday. Temperatures will warm early next week and increase the mountain snow melt. This could lead to rises on area rivers and streams. IDZ002-003-026-027-WAZ031>036-044-200830- COEUR D'ALENE AREA-IDAHO PALOUSE-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- WATERVILLE PLATEAU- 120 AM PDT Fri May 19 2017 This Hazardous Weather Outlook is for portions of North Idaho... North Central Idaho...Central Washington...East Central Washington...Northeast Washington and Southeast Washington. .DAY ONE...TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY No hazardous weather is expected at this time. WAZ038-041>043-200830- OKANOGAN HIGHLANDS-WENATCHEE AREA-EAST SLOPES NORTHERN CASCADES- OKANOGAN VALLEY- 120 AM PDT Fri May 19 2017 This Hazardous Weather Outlook is for portions of North Central Washington. .DAY ONE...TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Temperatures will warm early next week and increase the mountain snow melt. This could lead to rises on area rivers and streams.
The national radar mosaic for the moment the first event began.
1 debris flow. Local standard time, as filed.
Washington State Patrol reported a debris flow partially blocking Highway 25 twelve miles south of Kettle Falls.
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: 699569.