Periodic heavy rain and spring-time snow melt during March and April produced saturated soil conditions over north Idaho. Even during dry periods scattered debris flows continued to occur in the mountainous regions of north Idaho 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 March and April produced saturated soil conditions over north Idaho. Even during dry periods scattered debris flows continued to occur in the mountainous regions of north Idaho 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 18, 3:41 AM PST, 5 hours 19 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 441 AM PDT Thu May 18 2017 .SYNOPSIS... Scattered showers and a few thunderstorms will be possible again this afternoon. High pressure begins to build over the region Friday, before an upper level disturbance brings a renewed threat for showers and thunderstorms Saturday, especially in eastern WA and the ID panhandle. Sunday through early next week will see temperatures continue to climb above normal under the building ridge of high pressure. && .DISCUSSION... Today through Friday night: Anticipate a slow warming and drying trend. The upper low pressure system responsible for recent rain and snow will continue to pull away from the Inland Northwest. Nonetheless, a band of moisture from it will remain with an elongated upper trough over north Idaho. Winds will be light and there looks to be little to push it out of the region. Currently a mid level overcast deck lingers east of the Cascades into north Idaho. Light spotty showers remain, more so over the Idaho Panhandle into the morning hours. Snow levels are on the rise, near 6K ft which should keep any additional light snow in the higher elevations. Patchy fog will also be concern this morning where the clouds thin, more likely in the Cascade valleys. By this afternoon, surface based instability will increase and anticipate a return of convective clouds and showers. The best area of instability looks to be over northeast Washington and north Idaho, albeit very weak with capes of 150-300 j/kg and LIs of -1 to -2. Enough to include a slight chance of thunderstorms over the higher terrain late this afternoon and early evening. Temperatures will moderate today, rising about 3-8 degrees over yesterday. Skies should partial clear overnight as showers decrease, although boundary layer moisture will be high and could see a return of patchy fog in the valleys by early Friday morning. Then expect drier and warmer weather Friday as a ridge of high pressure begins to build in from the southwest. Under light winds, anticipate additional warming which should bring temperatures right near average for mid May. Instability will increase again by Friday afternoon with the main threat over north Idaho, but should see just a small chance of mountain showers lingering into the early evening. Mid level moisture and a few showers will spread in from the northwest with the arrival of an upper level shortwave late Friday night. /rfox. Saturday remains to be the focus for impactful weather. Our wrinkle in the building upper level ridge is on track...maybe just a smidge faster than previous runs. Convective parameters (CAPE 200-500 J/Kg in northeast WA and peaking over the central ID panhandle at 500-1000 J/Kg) remain sufficient to keep the mention of thunder in the forecast. A potential bust factor is abundant low level moisture in the form of overcast skies could limit instability as the shortwave approaches resulting in scattered showers over ID and isolated over WA. The latest NAM is suggesting that the slightly earlier arrival of the shortwave will actually result in showers during the morning and early afternoon hours and then a clearing trend begins during the afternoon. Not high enough confidence to put these details in the forecast quite yet so maintained the chance of showers and slight chance of thunderstorms wording. After Saturday, the trend will be warmer and dryer for several days. High pressure builds over the PacNW coast and remains fixed through at least early next week. Temperatures creep up each day through Tuesday. Beyond Tuesday, the models continue to have a different idea of how an upper level low will drop south out of Canada. The EC...which is the outlier...is persistent though with its much farther west and vigorous wave dropping over Washington. This would bring clouds and increased chances of rain as early as Wednesday if it pans out. Stay tuned...could result in continued above average temperatures and dry conditions or return to cool and wet. /AB && .AVIATION... 12Z TAFS: Mid level moisture band lingers over north Idaho with a spotty showers early this morning. Trends show these showers will be weakening but may be in the vicinity of KPUW and KLWS. VFR conditions are anticipated this morning with a low chance of MVFR with the showers. By the afternoon instability hit- and- miss showers will be possible, with the better risk closer to the mountains but some may stray into the vcnty of eastern TAF sites after 21z. By 02z, convective clouds and showers should decrease for the night. /rfox && .PRELIMINARY POINT TEMPS/POPS... Spokane 64 45 69 49 71 49 / 10 10 0 10 30 10 Coeur d'Alene 63 43 68 46 69 46 / 20 20 10 10 60 20 Pullman 61 41 67 44 68 45 / 20 10 10 0 40 20 Lewiston 66 45 73 50 74 50 / 10 10 0 0 40 20 Colville 65 43 69 48 73 48 / 30 10 10 10 40 10 Sandpoint 64 40 67 43 67 44 / 20 20 10 10 70 30 Kellogg 62 39 68 41 66 43 / 30 30 20 10 70 30 Moses Lake 72 45 76 51 78 51 / 0 0 0 0 10 0 Wenatchee 71 48 75 52 76 52 / 10 10 0 0 10 0 Omak 73 42 74 50 75 49 / 20 10 0 0 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
Hazardous Weather Outlook National Weather Service Spokane WA 602 AM PDT Thu May 18 2017 IDZ001-004-WAZ037-038-191315- NORTHERN PANHANDLE-CENTRAL PANHANDLE MOUNTAINS- NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS- 602 AM PDT Thu May 18 2017 This Hazardous Weather Outlook is for portions of North Idaho... North Central Washington and Northeast Washington. .DAY ONE...TODAY AND TONIGHT Isolated thunderstorms are possible this afternoon. Most storms will be weak with brief downpours and isolated lightning. Stronger storms may bring gusty winds and small. .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>036-041>044-191315- 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-WENATCHEE AREA- EAST SLOPES NORTHERN CASCADES-OKANOGAN VALLEY-WATERVILLE PLATEAU- 602 AM PDT Thu May 18 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...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY No hazardous weather is expected at this time.
The national radar mosaic for the moment the first event began.
1 debris flow. Local standard time, as filed.
The Forest Service reported a debris flow cutting Prospector Creek Road near Calder which necessitated a temporary road closure.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2017Every state in 2017This day in weather historyWarnings in Idaho, 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: 699572.