A slow moving storm brought heavy rains to the area. Rain and snow melt led to a debris flow near the 25 Mile Creek Burn Scar.
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The episode as NWS OTX wrote it up.
A slow moving storm brought heavy rains to the area. Rain and snow melt led to a debris flow near the 25 Mile Creek Burn Scar.
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 8, 3:24 AM PST, 5 hours 51 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 424 AM PDT Mon May 8 2023 .SYNOPSIS... Widely scattered showers and thunderstorms will be possible through Tuesday with the threat slowly waning around midweek. A strong warming and drying trend will arrive for the latter half of the week and continue into the weekend. Afternoon temperatures near ninety degrees or warmer will be possible Sunday into early next week. && .DISCUSSION... A closed upper level low offshore the OR/CA coast will weaken and move eastward into OR later this morning and bring the chance for showers and thunderstorms, particularly in SE WA/Southern Panhandle. Destabilization begins around 10-11 AM and with little to no capping inversion. Shower and thunderstorm development will occur in the Blue Mountains/Northern Mountains/Cascades and move N/NW (widespread 30-50% chance). Synoptic forcing improves throughout the afternoon especially in the southeast. Shear profiles look unimpressive so a pulse-like storm mode is likely. The strongest storms will be in the mid afternoon in SE WA/Southern Panhandle with gusty outflow winds, small hail, and heavy rainfall. Temperatures will peak in the 60s today. Shower activity is sustained tonight by a pivoting deformation band. Impacts with the deformation will be slim with perhaps a stray lightning strike. Additional showers and thunderstorms initiate in the Northern Mountains tomorrow afternoon as well. Those will also be capable of heavy downpours with PWAT anomalies around 120-140%. Temperatures Tuesday will be in the upper 50s to 60s in most spots. The Okanogan Valley will be the warm spot outside of the influence of the deformation band. db Wednesday and Thursday: The remnants of the offshore trough will lift through the Northwest Wednesday and exit to the east on Thursday. Wednesday will bring one more day of hit or miss showers and 10-20% chance for weak thunderstorms as cool 500mb temperatures near -23C remain overhead. Cannot rule out a weak vort max drifting across the northern mountains Wednesday afternoon focusing a heavier cluster of showers but overall, this period looks to be lacking any organized dynamics with shower generation largely reliant on afternoon heating. High pressure will begin to strengthen over Central WA Thursday morning and expand into North Idaho by the evening. This will allow for one more day of diurnally driven showers across Idaho Panhandle but warming aloft over Central WA looks to bring an end to any precipitation threat. Eastern WA will be in the transition zone during the afternoon hours. Odds favor dry conditions but would expect some cumulus buildups and cannot rule out a few sprinkles or brief light showers. Wednesday will start off cool with widespread 40s and a few of our northern valleys likely to be in the mid to upper 30s. Temperatures rebound in the afternoon back into the 60s. It will be a degree or two warmer Thursday morning then look for afternoon temperatures to climb into the 70s. Friday through Sunday: Nearly 100% of the ensembles support an anomalous strong upper-level ridge over the Inland Northwest this weekend and likely carrying over into early next week. This pattern will delivering another period of well above normal warmth and dry conditions. How long does the heat last and how hot will it get? Those questions still carry some uncertainty. There is high confidence that the air mass will warm 3-5 degrees Celsius each Friday and Saturday yielding a net warming of 5-7 degrees at the surface each afternoon. This will push high temperatures into the upper 70s to 80s Friday then widespread 80s Saturday. The warming trend is likely to continue Sunday and well into next week with upper 80s to 90s but we continue to find roughly 25% of the 100 member ensemble suites supporting some disruption of the ridge courtesy of an offshore trough around the start of the work week. This low probability event does become evident within the box- whisker plots of temperatures (i.e. the lower whisker) however since this is a very low chance and 25-75% of the members support continued warming, our forecast leans in this direction for Sunday-Monday. Ridges of this magnitude are typically hard to shove inland or breakdown also supporting the notion for additional warming Sunday and near to warmer temperatures Monday- Tuesday. Heat may become an issue for sensitive populations, especially for anyone without a proper means to cool off at night. The warmth will also bring another period of increased mountain snow melt keeping our rivers running high but general low probabilities for flooding. Based on the current snowpack, we will need to keep a close eye on the Stehekin and Okanogan Rivers which carry the highest probabilities for reaching levels near minor flood stage. /sb && .AVIATION... 12z TAFs: VFR conditions are expected through the period. Convection will again impact the region (widespread 30-50% chance of showers and thunderstorms) during the afternoon and evening hours (20z-04z). Low confidence if any thunderstorms will impact TAF sites, but PUW/LWS have the better chances than the other terminals. Any thunderstorms at the terminals should be limited and brief with lightning, brief heavy rain and small hail. A secondary band of precipitation forms around 07-10Z tomorrow and moves slowly northward (20-50% chance of showers for KPUW-KGEG- KSFF- KCOE-KMWH). db && .PRELIMINARY POINT TEMPS/POPS... Spokane 65 43 59 43 68 45 / 30 30 60 30 10 0 Coeur d'Alene 64 41 58 42 66 44 / 30 30 70 50 10 10 Pullman 63 42 55 40 65 43 / 50 60 70 20 10 0 Lewiston 69 49 62 45 71 49 / 50 60 60 20 10 0 Colville 66 40 68 42 68 43 / 30 20 40 40 20 10 Sandpoint 62 42 62 44 64 43 / 40 20 50 60 30 10 Kellogg 62 43 56 43 64 45 / 40 40 80 50 20 10 Moses Lake 69 47 65 43 73 47 / 20 50 30 10 0 0 Wenatchee 68 47 68 46 71 49 / 30 40 30 10 10 0 Omak 67 45 70 47 71 48 / 30 20 20 20 10 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
The national radar mosaic for the moment the first event began.
1 debris flow. Local standard time, as filed.
Debris flow and flooding near Eagle Creek off the Twisp River. Several large logs and mud moved down the channel and impacted the forest service roads. Rain, for areas around the spot, several days prior ranged from 0.30-1 inch.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2023Every state in 2023This day in weather historyWarnings in Washington, May 2023
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: 1105036.