OTX Forecast Discussion

000 FXUS66 KOTX 042259 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 259 PM PST Thu Dec 4 2025

KEY MESSAGES

SYNOPSIS

The weather will trend much more unsettled Thursday through the weekend. Temperatures look to be cold enough tonight into Friday to support a lowland wintry mix. By Friday, temperatures will modify and warm above normal with unsettled weather continuing through the weekend and into next week.

DISCUSSION

MIXED VALLEY PRECIPITATION AND MOUNTAIN SNOW THROUGH THIS

WEEKEND TO BRING THE POTENTIAL FOR TRAVEL IMPACTS…

Thursday and through Friday: The first wave of precipitation has moved through and the bulk of the wintry precip at this point is south of I-90 early this afternoon. Precipitation will continue to decrease from north to south this evening leading to a brief break before the next wave of precipitation moves in Friday morning. There is a minor freezing rain threat primarily on the Waterville Plateau again early Friday morning before surface temperatures warm above freezing. Have held off on any additional winter weather advisories for now given uncertainty for surface temperatures. Expecting mostly rain with this system except the cooler northeast valleys where up to an inch of snow will fall Friday morning.

Friday afternoon through Saturday: There will be a cold front passage Friday evening associated with the occluded surface low hanging back in SW BC. Snow levels will drop at the mountain passes leading to a changeover to snow. Stevens Pass will see around 5-10” of wet heavy snow Friday night through Saturday evening. Lookout Pass will receive another 4-8” inches of snow as well. Strong winds will develop in the wake of this frontal passage around 45-60 kt in the 2-6 kft layer leading to strong westerly winds gusting up to 55 mph. in the Wenatchee area, Waterville Plateau, and the Alpowa summit area Friday night into Saturday. Peaks around 3000-6000’ in the east slopes of the Cascades have potential to gust around 55-70 mph.

Sunday through Thursday: Snow levels rise above 4000 feet minimizing wintry impacts in the lowlands. The mountain passes are not completely out of the woods for winter impacts just yet, especially Stevens Pass. An active storm track will favor rounds repeated subtropical moisture into the region next week. Monday and Wednesday next week look particularly interesting as models suggest PWATs anomalies could rise above a staggering 300% of normal. This pattern would bring a lot of rain to the Cascade crest and Idaho Panhandle with strong westerly flow. How much rain? Models suggest around 5- 10” in the Cascades and around 2-6” for the Idaho Panhandle. So concerns will shift to mud and rock slides in steep terrain due to rain and snow melt, and rises on rivers and small streams. At this time no flooding is forecast in eastern WA and north ID. DB

AVIATION

00Z TAFs: Widespread IFR and MVFR stratus will impact aviation over Central and Northeast Washington and the ID Panhandle. With the exception of the Cascades, precipitation overnight to largely remain along and south of a KEAT-KMWH-KCOE line. IFR/LIFR conditions expected to settle back into NE WA and N ID by Friday morning. Lower confidence for evolution of low clouds around KEAT overnight. Precip to expand again after 15Z Friday.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:

High confidence of widespread IFR and MVFR conditions across the region into Friday.

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 from 7 PM Friday to 7 AM PST Saturday for Lower Garfield and Asotin Counties-Waterville Plateau-Wenatchee Area. Winter Weather Advisory from 7 PM Friday to 10 PM PST Saturday for Western Chelan County. ID…Winter Storm Warning until 4 PM PST Saturday for Central Panhandle Mountains.

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