textproduct: Spokane

KEY MESSAGES

- Mostly dry conditions through Wednesday.

- Two systems moving in mid to late week will bring light rain and mountain snow.

SYNOPSIS

Temperatures will be seasonal and it will be mostly dry through Wednesday in the Inland Northwest. Mountain snow showers and rain showers return mid to late week as two systems move through. Unsettled conditions continue into the weekend and early next week.

DISCUSSION

Tuesday and Wednesday: An upper level low sliding through northern California today will bring thickening clouds to the Inland NW a small chance of sprinkles to central Washington in the morning. Clouds will begin to clear out in the evening as the system departs into Nevada, leaving Wednesday dry and mild. Temperatures Tuesday and Wednesday will be in the upper 40s to 50s.

Thursday through Tuesday: Another system comes hot on its heels early Thursday into the Pacific NW. Snow levels will be around 4000- 5000 feet in the Cascades early Thursday, but favorable synoptic ascent is short lived as the decaying shortwave trough races through the region and departs in the afternoon Thursday. There is a 20 percent chance of at least 1 inch of snow at Washington Pass Thursday morning. This will also bring light rain to eastern WA and north ID in the morning and afternoon, but amounts look very unimpressive around a trace to a tenth of an inch.

Another shortwave will brush through the region Friday and this system will have more moisture to work with but the best synoptic ascent is displaced to the north in Canada. Strong westerly flow will maximize preciptiation near the Cascade crest where a tenth to half an inch of precipition is forecast Friday and Friday night. Snow levels will start off around 4000-4500 feet in the morning bringing snow to both Stevens and Washington Pass but rise above 5000 feet in the afternoon. The chance for at least 1 inch of snow at Stevens Pass from Friday morning to Friday night is 10%. Those chances increase to 45% for Washington Pass. We will take anything we can get. Outside of the Cascades, precipitation amounts will be light around a trace to a few hundreths with this system.

Unsettled conditions continue into the weekend primarily in the mountains. Global ensembles are coming in better agreement that the Pacific NW will be on the edge of high pressure to the east and low pressure to the west. Snow levels at least initially appear to high to get snow at the Cascade Passes Saturday but there is a 25% chance of at least 6 inches of snow at Washington Pass Sunday and Monday. A similar pattern appears to set up into next week with the longwave trough remaining anchored in the northeast Pacific. /DB

AVIATION

18Z TAFS: Mid and high level clouds will continue to move into the region through tonight before thinning Wednesday morning. A few breaks in the clouds combined with surface observations reveals areas of IFR/MVFR stratus in the northern valleys this morning but not impacting any of the TAF sites. Expect these to lift and dissipate by mid to late afternoon. Overnight as the high clouds begin to thin with a moist boundary layer areas of fog and stratus are expected to again develop over the northern valleys. Models also show a chance for fog and stratus developing across the Columbia Basin into Spokane/Coeur d'Alene area, the Palouse, and LC Valley. But with probabilities at 50 percent or less confidence in coverage more than patchy is low so only went with a FEW-SCT low cloud deck for KMWH/KGEG/KSFF/KCOE/KPUW/KLWS. JW

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions for all TAF sites through this evening. Low confidence in ceiling and visibility for all TAF sites except KEAT after 11z Wednesday as areas of stratus and patchy fog develop.

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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

Preliminary Point Temps/PoPs

Spokane 50 35 51 36 49 35 / 0 0 0 10 70 0 Coeur d'Alene 51 36 51 36 47 36 / 0 0 0 0 80 10 Pullman 51 34 50 35 48 33 / 0 0 0 10 70 0 Lewiston 53 38 53 40 53 38 / 0 0 0 10 50 0 Colville 50 28 52 32 48 27 / 0 0 0 10 60 10 Sandpoint 49 34 50 35 44 34 / 0 0 0 0 80 20 Kellogg 53 36 53 35 46 35 / 0 0 0 0 90 20 Moses Lake 54 30 53 35 55 32 / 0 0 0 30 20 0 Wenatchee 52 36 52 39 55 39 / 20 0 0 20 10 0 Omak 52 33 53 38 52 34 / 10 0 0 10 10 0

OTX WATCHES/WARNINGS/ADVISORIES

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