OTX Forecast Discussion

000 FXUS66 KOTX 111224 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 424 AM PST Thu Dec 11 2025

KEY MESSAGES

SYNOPSIS

Winds will taper off through the day Thursday while areas of rain linger. Friday and Saturday will bring a brief break. A weak system moves in Sunday bringing light rain the mountains. Confidence is increasing for another round of rain and high mountain snow Monday before snow levels begin to decrease by the middle to end of next week.

DISCUSSION

 RAIN AND SNOW MELT CONTINUES THURSDAY WITH FLOODING IN THE CASCADES AND SMALL STREAM FLOODING IN THE IDAHO PANHANDLE...

Today through Friday: The atmospheric river responsible for all the wind, rain, and snow melt over the past several days will slowly lose its grip over the Inland NW the next couple days. The atmospheric river will shift from northern WA/north ID Panhandle this morning down into southern Washington and the south ID Panhandle this afternoon. This will allow the Cascades and Northern ID Panhandle to see rain decrease heading into the afternoon while rain develops across SE Washington. Yet the atmospheric river wind components decreases this afternoon as 850mb winds decrease from 50-60 kts through early morning to 20-30 kts in the afternoon. Additional rain amounts from 4 AM this morning to 10 AM Friday are expected to range from a quarter to half inch over SE Washington into the south ID Panhandle and along the East Slopes of the Cascade Mountains, except locally up to 1 inch in the mountains and along the Cascade crest. The decrease wind component of the AR will also allow the gusty winds to decrease through the morning. Snow levels will also be on the decrease over northern WA today, falling to 3000-5000 feet which will reduce snow melt runoff.

All this said, we are nearing the peak of the flood event, with most rivers and streams expected to begin falling later today after cresting this morning. Flood Warnings and Advisories remain in place for several rivers, as well as small streams in the Cascades and ID Panhandle. Mud and rock slides will remain a threat today as well. Tonight into Friday the atmospheric river lifts back north again, but with much less lift as it lifts north due to a building ridge. Net result will be areas of light precipitation focuses mainly over the Cascades and ID Panhandle. Snow levels rise again however to 6000-7000 feet except 4000 feet near the Canadian border of NE WA/N Idaho which will lead to more high elevation snow melt.

Saturday through Tuesday: Broad southwest flow through Monday will keep temperatures unseasonably mild by mid-December standards with snow levels ranging from 5000-7000 feet. On Monday another atmospheric river moves through the region but thankfully this looks to be of shorter duration. Yet the snow melt and increased precipitation will likely keep rivers and streams elevated in the Cascades and ID Panhandle with additional rises possible. The wet pattern continues into next week as several systems move in from the west or southwest. Although snow levels may begin to come down for snow to the return to the mountains. But for the valleys expect precipitation type to be rain through at least Tuesday. JW

AVIATION

12Z TAFs: Winds are will continue to weaken through the morning. On Thursday as the downslope flow begins to decrease and a band of moisture sags south, light rain is expected to develop at KPUW/KLWS which will moisten the boundary layer with MVFR conditions developing at KPUW. The cloud decks could are expected to drift northward and bring a low VFR ceiling KGEG- KSFF and MVFR to KCOE. MVFR ceiling is expected to form over KEAT as rain through the day keeps the boundary saturated.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence

for VFR conditions through the day. Moderate to high confidence for MVFR ceilings at KPUW. Moderate confidence for MVFR ceilings at KCOE-KEAT. JDC

Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports,please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard

OTX WATCHES/WARNINGS/ADVISORIES

WA…Wind Advisory until 7 AM PST this morning for Spokane Area- Upper Columbia Basin-Washington Palouse. High Wind Warning until 7 AM PST this morning for Lower Garfield and Asotin Counties. ID…Wind Advisory until 7 AM PST this morning for Coeur d’Alene Area-Idaho Palouse.

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