A several day period of continuous rain caused a rock slide along Highway 20 near Sherman Pass. 1 inches fell from November 1 through November 4.
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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.
A several day period of continuous rain caused a rock slide along Highway 20 near Sherman Pass. Rainfall amounts from 0.9 to 1.1 inches fell from November 1 through November 4.
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 Nov 4, 4:40 AM PST, 1 hour 20 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 540 AM PDT Sat Nov 4 2023 .SYNOPSIS... A wet storm system will spread rain across the Inland Northwest today. Rain will produce ponding of water in poor drainage areas and rises on small streams and creeks, but flooding is not expected. Additional wet weather is expected Sunday night through Tuesday with rain in the valleys and light snow in the mountains. A period of drier weather looks likely around the middle of next week and then a return of unsettled weather approaching next weekend. Temperatures will be near normal through this weekend into next week. && .DISCUSSION... Today and Tonight: A moderately strong Atmospheric River, AR2 event, will impact the Northwest over the next 24 hours. The warm conveyor belt with a P-wat plume of near 1.5 inches can be seen on satellite imagery being direct into the state of Washington early this morning. Frontal passage will be in the afternoon and is slightly delayed compared to model runs from 24 hours prior. This will lead to rain hanging around an hour or two longer over extreme eastern Washington and into the Idaho Panhandle today. It looks likely that the Idaho Panhandle will see steady rain continuing through much of the day and won't begin to start shifting out of the Northeast Mountains and the Northern Panhandle until this evening. Moderate to heavy rainfall totals are expected over the Cascade crest of 2+ inches will be likely. These totals will be similar to what we experienced with the precious AR event we just had. Small streams, creeks, and the Stehekin River in the east slopes of the Cascades will be seeing sharp rises with the absent of snowpack to soak in all of this water. The good news is that the moisture plume will shift south of these areas by mid afternoon, and this should be soon enough that I don't expect flooding issues to crop up. The Stehekin River will be approaching bankfull and other rivers and streams will likely be seeing debris coming down through the watershed. Minor rock slides will also be possible. It will be a wet start to the day across the rest of eastern Washington. We should see the rain shutting off over the Columbia Basin by the afternoon as the front slides east of the Cascades and westerly flow results in downsloping on the lee side. Rainfall totals around Wenatchee to the Okanogan Valley and Moses Lake Area will be between a tenth and a quarter of an inch. Those totals will be significantly higher in the more favorable upslope areas of the Idaho Panhandle with around 0.75 to 1.25 inches expected. The mountains in the Idaho Panhandle will see the potential for 1.5 to 2.0 inches when all said and down tonight. The main concern with this rainfall will be for rises on small streams and for minor slides in steep terrain. Paradise Creek that runs through Moscow will see a sharp rise, but it's unlikely we will see enough rainfall for this flashy creek to cause flooding impacts. The atmosphere does destabilize behind the front this afternoon across northern Oregon into southeast Washington. There will be a small chance for thunderstorms to develop near the Blue Mountains and storms could then move northeast into the Lewiston-Clarkston Valley and Palouse. CAPE will be quite limited though, so I don't expect much in the of lightning even if we do see convection develop and move up into these areas. Any thunderstorms that develop will be capable of brief heavy rain, pea sized hail, and gusty winds. Sunday through Monday night: A break between weather systems is expected on Sunday; however, we will continue to see moist upslope flow into the Cascades and Idaho Panhandle where residual showers will continue to be a possibility into Sunday afternoon. Another storm system will move in Sunday night on the heels of the storm today. It will be the third in the parade of storms rounding out the weekend into early next week. This third storm system will feature a moisture plume that will contain less in the way of total moisture content than the previous two with lighter precipitation in comparison. A frontal band will track across Sunday night into Monday with around a tenth to a quarter of inch of precipitation over the Columbia Basin and a half of an inch up to around an inch over northeast Washington and into the Idaho Panhandle by Monday night. Snow levels will also be lower with this storm at around 5,000 feet in the Cascades and Okanogan Highlands by Monday and lowering further to around 4,500 feet overnight on Monday. This may result in light snowfall over Stevens Pass and Sherman Pass Monday night. /SVH Tuesday through Friday: Unsettled pattern continues. Ensembles suggest Tuesday starts out with an upper level trof with enough of a conditionally unstable airmass pushing through to keep pops going with westerly downslope keeping portions of the Western Columbia Basin and Waterville Plateau trending toward a dry forecast. This trof translates eastward rather quickly allowing for a drier northwest flow ahead of ridging to expand the earlier mentioned rain shadow out to the east and west Tuesday night into Wednesday with ridging taking hold and allowing further drying Wednesday night into Thursday. The ridging is expected to be quite transient as another weather system with a weak and not very effective tap into subtropical moisture passes through Thursday night into Friday. The earlier discussed drier northwest flow Tuesday night into Wednesday will allow enough cold air advection to drop snow levels down to the near 3000-4000 feet MSL range Tuesday night into Wednesday. The upper level ridging Wednesday night into Thursday will allow for lower level surface winds from the northeast to bring in cooler air further lowering the snow levels to near 3000 feet MSL. More or less a general cooling trend in temperatures remains in place that continues to at least Wednesday with more uncertainty and lower confidence after. /Pelatti && .AVIATION... 12Z TAFs: Rain across the Inland Northwest will produce widespread IFR conditions today. Frontal passage will take place this afternoon and enhanced dynamics along the front is expected to produce a period of moderate rainfall rates with low IFR conditions possible over extreme eastern Washington and the Idaho Panhandle between 18Z-00Z. Marginal VFR conditions are more likely at the Pullman/Moscow Airport (PUW) and Lewiston Airport (LWS) today due to downsloping off of the higher terrain at these terminals; however, the heavier rain with frontal passage may result in IFR conditions between 19-23Z this afternoon. There is a small chance for isolated thunderstorms in the vicinity of PUW and LWS between 23-04Z this evening. Low stratus cover with IFR conditions is expected to develop behind the front overnight into Sunday morning impacting airports from Omak to Moses Lake to Lewiston and points northeastward into the Idaho Panhandle. There is high confidence with the forecast of rain and impacts through this afternoon. There is low confidence for convection and thunderstorms to develop this evening. /SVH && .PRELIMINARY POINT TEMPS/POPS... Spokane 55 41 53 39 51 39 / 100 50 10 60 100 80 Coeur d'Alene 51 42 51 39 49 39 / 100 80 30 70 100 90 Pullman 53 40 54 39 51 38 / 100 100 20 70 100 90 Lewiston 58 45 59 44 57 43 / 100 90 20 60 90 80 Colville 48 31 49 32 47 32 / 100 50 20 70 100 90 Sandpoint 47 39 49 37 45 36 / 100 80 60 70 100 100 Kellogg 52 43 49 41 48 40 / 100 100 60 70 100 100 Moses Lake 54 35 54 39 55 37 / 100 10 10 60 80 40 Wenatchee 52 40 53 44 50 41 / 100 10 20 70 80 50 Omak 51 38 52 41 50 38 / 100 10 10 60 90 60 && .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.
WSDOT cleared a rockslide on Highway 20 at MP320. No mention of how big the slide was.
After NWS Directive 10-1605, the rules offices file Storm Data by.
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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: 1149092.