textproduct: Spokane

KEY MESSAGES

- Weather remains active through the week.

- Periods of winter driving conditions over Cascade passes.

SYNOPSIS

Several storm systems will impact the region through the week, each bringing valley rain and high mountain snow. Mountain passes could have winter driving conditions through the week. Breezy winds across the Basin Tuesday and Friday afternoons.

DISCUSSION

Tonight through Monday: A 130kt upper level jet over the Pacific Northwest will track small Low pressure system into the northern OR coastline into Monday. It will bring increasing mid to high level clouds to the Inland Northwest for Sunday evening. High pressure over Southern BC is keeping the moisture along southern WA and Lower ID Panhandle through the morning. Precip chances will creep further North as the Low continues to move Southwest to Northeast across the Inland Northwest. By Monday afternoon, the region has at least a 40% chance of precip excluding the Okanogan Valley(20%). Precip amounts are highest along the Cascades and Central Panhandle mountains with around half an inch. The rest of the region can expect up to two tenths. For precip type, snow levels will start around 3500ft before rising through the day. It will keep the low lands as rain. Stevens and Washington Pass have a 70% probability of at least 2 inches of snow through Tuesday morning. These areas could get as much as 5 inches. Snow levels for Lookout Pass will be around 6000ft limiting snow impacts. Overnight lows will be in the upper 20s and 30s. Mondays highs will be in the 40s and low 50s. Any precip chances will diminish be Tuesday morning.

Tuesday and Wednesday: As the jet and remains of the low exit the region, the Pacific Northwest will become wedged between a strengthen ridge east of the Continental Divide and a deepening trough along the coast. Any precip chances will diminish be Tuesday morning. A Gulf of Alaska Low will bring a wave of moisture across the Inland Northwest that is around 200% of normal precipitable water (0.8-1 inch). Precip chances will be at least 80% across the region. The warm air associated with the wave will bring snow levels 6000ft by Wednesday morning. Ensembles are indicating another Cascade Pass snow event with around 4 to 6 inches expected through Wednesday. Precip amounts range from 0.2-0.4 of an inch for the higher terrain and 0.1-0.3 of an inch for the lower terrain. Areas of the Cascades see amounts around 0.6-0.8 of an inch. Winds will be breezy across the Central Basin with gusts into the low 20s mph. Highs will be in the upper 40s and low 50s. Lows will be in the 30s and low 40s.

Thursday through Saturday: For Thursday morning, the region will again have another break before the Low pushes another wave across the region. Ensembles are beginning to diverge on the timing and moisture associated with it. Highest precip amounts are expected to be along the Cascades due to the east to west trajectory of the wave. The rain shadow effect lowers the confidence on precip amounts for the rest of the region. For now, the Cascades will again have high precip amounts up to an inch. With lower snow levels, the Northern Cascades and Washington Pass could see near a foot of snow through through Saturday. Precip amounts for the rest of the are around 0.1-0.3 of an inch. Winds will be gusty across the Basin on Friday into Saturday with gusts into the low 30s mph. Highs will be in the upper 40s and 50s. Lows will be in the 30s and low 40s. /JDC

AVIATION

00Z TAFS: An incoming system will bring increased clouds and precip chances across the region. High clouds will begin to increase overnight. Very light precipitation in the form of flurries or sprinkles may fall in the Cascades and northern mountains by Monday morning, but not expected to bring much in the of impacts to airports as any precipitation won't moisten the boundary layer up much. Short term ensembles are showing potential low level cloud development across the Inland Northwest for early Monday morning. By the afternoon, MVFR ceilings expected across the region with showers occurring at the TAF sites.

.FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence remains high for VFR conditions through tonight. There's a 40-60% chance for stratus producing MVFR ceilings between 1,000-3,000 ft agl. between 16-20Z Monday morning for all TAF sites excluding LWS. Low confidence on rain showers lowering visibilities to MVFR at TAF sites. /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:/weather.gov/otx/avndashboard

Preliminary Point Temps/PoPs

Spokane 34 46 36 47 38 51 / 0 50 80 60 70 90 Coeur d'Alene 33 45 36 46 38 50 / 10 60 80 70 70 90 Pullman 33 45 37 50 40 53 / 0 60 90 70 70 80 Lewiston 36 50 43 58 46 60 / 0 50 90 50 50 70 Colville 25 46 27 45 28 45 / 0 40 60 50 70 100 Sandpoint 30 43 32 43 34 46 / 10 70 80 70 80 90 Kellogg 34 44 39 46 40 50 / 10 80 90 90 80 90 Moses Lake 36 49 36 50 40 53 / 0 20 70 40 80 90 Wenatchee 38 46 39 47 41 48 / 10 40 70 40 90 90 Omak 33 47 34 48 37 49 / 0 30 40 30 70 100

OTX WATCHES/WARNINGS/ADVISORIES

WA...None. ID...None.