Preparing for Wet Mountains and Foggy Valleys: Eastern WA & ID Panhandle Adventure Outlook

October 30, 2025

A compact, wet pattern is arriving for the mountains and a stubborn layer of valley stratus and fog is clinging to the lowlands. Think of this week as a tussle between low, damp mornings in the basins and progressively wetter, milder systems punching into the high country. Read on if you’re planning hiking, backpacking, driving over passes, photographing fog, or paddling rivers — the NWS Spokane Area Forecast Discussion contains clear signals we can translate into practical adventure plans.

The headline meteorology: a relatively mild, moisture-rich system will arrive Friday night into Saturday. Models agree this one will tap an atmospheric river (AR) signature — the forecast team highlighted precipitable water anomalies around 200–260% of normal. In plain language: expect efficient, persistent rain for the Cascades and the Idaho Panhandle mountains with the potential for moderate to heavy totals along the crest Friday night into Saturday. Snow will be a high-elevation issue in the Cascades, with light accumulations possible at higher passes and some travel impacts over Washington Pass.

Valley fog and stratus will be the nuisance story through Friday morning. High pressure today keeps a shallow, stubborn low cloud deck entrenched across the Spokane and Coeur d'Alene basins. Aviation forecasters note IFR/LIFR conditions at GEG, SFF, and COE through the evening and a chance for improvement 21–00Z, but confidence is low — these low clouds have been hard to predict and could persist. If you’re a photographer or an early-hiking planner, expect dense, lingering fog in valley bottoms both tonight and Friday morning.

Timing and quantitative expectations: Friday daytime is mostly dry across most inland areas, though the Cascades will begin to see rain by late afternoon. The main moisture surge arrives Friday night, expanding across eastern Washington and northern Idaho. Saturday is the core day for steady precipitation region-wide — the east third of WA and northern zones can expect ~0.25–0.5 inch of rain in many spots; higher terrain will see higher totals (about an inch possible), and the Cascade crest could pick up 1–3 inches of rain. The deeper lee basins downwind of the Cascades will stay much drier (only a few hundredths to a tenth of an inch possible) because of shadowing in the prevailing westerly flow.

Snow levels are generally high for this first system — most snow will remain confined to the high mountains. Saturday into Saturday night could put light accumulations on Washington, Stevens, and Sherman Pass; Washington Pass might see a couple of inches, with minor accumulations elsewhere. Winds will be light Friday, then increase Saturday: southerly winds in the morning shift westerly in the afternoon with gusts commonly in the 15–30 mph range in exposed locations before easing Saturday night.

Looking beyond the weekend, the pattern remains active through midweek. Expect a series of frontal waves late Monday into Tuesday and again Wednesday into Thursday. The late Monday–Tuesday system has the best shot at pass-affecting snow: forecasters targeted snow levels around 3,500–4,500 ft in the Cascades and 5,000–7,000 ft elsewhere, which is where Washington Pass and Stevens Pass could see more impactful snowfall (the discussion mentions roughly 1–3 inches in those passes with the Monday/Tues window). After that system, milder air pushes snow levels upward toward 6,000–8,000 ft.

For outdoor adventurers, what this means by zone:

• Cascades / High-country (Washington Pass, Stevens Pass, Sherman Pass): Plan for wet, potentially wintry travel from Friday night into Saturday and again late Monday–Tuesday. Light accumulating snow is possible Saturday night and more likely around the Monday/Tuesday system. If you’re planning ridge routes or passes, carry traction, winter clothing, and be prepared for rapidly changing visibility and road conditions. Washington Pass is the most at-risk pass this weekend for travel delays.

• Idaho Panhandle mountains (Sandpoint, Kellogg, northern Idaho ranges): Expect moderate to heavy rain on the crest Friday night–Saturday with mountain snow at the highest elevations. Daytime Saturday will be wet; river levels and trail crossings can rise quickly after heavy mountain rainfall.

• Spokane / Coeur d'Alene basins: Morning fog and low clouds tonight and Friday morning are likely. Saturday should be cloudier with occasional rain moving in overnight Friday–Saturday; precipitation amounts will be lower in the basin compared with the mountains. Road travel within the valley should be fine, but watch for wet roads and reduced visibility during fog episodes.

• Palouse / Pullman and lower elevations: Drier than the crest, but occasional rain showers will be possible Friday night into the weekend. Expect cool, damp conditions — trail surfaces will be slick.

• Columbia Basin (Moses Lake, Wenatchee) and lee-of-Cascades areas: These areas will be in the partial rain shadow for much of the event. You may get light showers and breezy conditions Saturday, but totals should be notably lower than the mountains.

Aviation and early starts: pilots and early-bird hikers should note the NWS emphasized low confidence in timing when stratus will clear across Spokane and Coeur d'Alene. If you rely on sunrise visibility — photography or summit starts — have a Plan B for valley fog. High confidence remains for VFR at upriver and coastal-plain airports (KPUW, KLWS, KMWH, KEAT) through the period.

Actionable adventure guidance for the week ahead:

• If you’re aiming for alpine objectives this weekend, move them earlier (Friday morning) or postpone. The highest likelihood for slippery, snowy approaches and limited visibility is Saturday and again late Monday/Tuesday. Be ready for trail wetness, saturated snow patches above treeline, and gusty winds.

• Road travel over Washington Pass and other high passes: monitor the WSDOT and Idaho DOT cams and the NWS updates. Washington Pass could see a few inches of snow Saturday night and greater impacts on the Monday/Tuesday system. Even small accumulations combined with packed snow and cold pavement can cause chain requirements and slower traffic.

• River runners and paddlers: heavy mountain rain will push water into the river network. Boaters should expect higher flows and faster currents following the peak rainfall Saturday. Low-elevation calm paddles (e.g., calm stretches of the Spokane River within the city) may still be feasible Friday, but scout put-ins and avoid exposed whitewater zones after heavy rain.

• Trail photographers and landscape shooters: the foggy valley mornings are your window for dramatic low-cloud imagery through Friday morning and likely again in the next few days. Saturday’s heavy mountain cloud deck will mute contrast but can create moody, atmospheric shots; protect gear from steady rain.

Key hazards to keep in mind: mountain and pass snow Sunday night into Tuesday, gusty westerly winds Saturday afternoon (15–30 mph), increased river flows after heavy rainfall, and persistent valley IFR/LIFR fog that reduces visibility during morning hours. The NWS explicitly called out that models have struggled to erode the stratus; that means localized surprises are possible — a route that looks clear on a model snapshot might remain socked in by low clouds.

Numbers to remember from the forecast team: PWATs (precipitable water) around 200–260% of normal for the moisture surge Friday night–Saturday — that’s the reason for wetter-than-usual mountain totals. Rain totals: ~0.25–0.5 inch across the eastern third of WA and to the north, around an inch in higher terrain, and 1–3 inches possible right at the Cascade crest. Lee basins may be held to only a few hundredths to a tenth of an inch.

Plan like this: for low-elevation outdoor activity choose late Friday daytime windows when the low clouds may lift and before the main surge arrives; treat Saturday as a lower-performace, wet day for outdoor sports in the mountains; expect increasing risk for pass closures and slippery conditions late Monday into Tuesday. Keep layers, waterproof gear, traction, and up-to-date road and pass information on your checklist. The week ahead is not a washout everywhere, but it prioritizes caution for mountain ventures and an opportunistic approach for valley photography and short, lower-elevation hikes between wet spells.

If you’re building an itinerary: schedule technical alpine objectives for days well beyond Tuesday and stack lower-elevation activities (bike rides, urban riverside walks, photography) into the Friday daytime window or later next week as the pattern sorts. Monitor the NWS for updates on snow-level changes and any watches/warnings for passes — the forecast confidence is higher on the broad pattern but lower on the fine details like fog timing and exact pass accumulations.

Bottom line for the outdoor week: expect damp, mild weather with a strong mountain focus for precipitation this weekend and an active series of systems next week that could bring true wintry impacts to the passes late Monday into Tuesday. Tread carefully on wet trails, watch the passes, and pack the rain shell.