Marine Weather and Tide Forecast for Spokane Valley, WA

SYNOPSIS
Strong high pressure will dominate the weather this week, keeping the Inland Northwest under stagnant air, lowland clouds, and mountain sun. Dry conditions will persist until at least Saturday, with the potential for a return of light precipitation Sunday or Monday.

DISCUSSION
Monday night through Tuesday: A strong upper-level ridge remains parked offshore the Pacific Northwest, with the Inland Northwest under the influence of a dry, stable pattern. Strong low- level inversions have kept the Inland Northwest under a blanket of stratus, with this trend continuing through the evening and into tomorrow.

Some subtle changes are expected on Tuesday as a weak wave drops east of the Continental Divide. This is not expected to bring precipitation to the Inland Northwest with drier continental air filtering into the region from the northeast.
Models show precipitable water values dropping from 0.25-0.30 inches this evening to 0.15-0.20 inches on Tuesday. Winds are expected to remain light and model soundings do not show the low-level inversions mixing out either. So while there may be some clearing across the Inland Northwest with this drier air, this does not seem to be robust enough of a system to bring widespread, continuous clearing across the region.

Wednesday through Tuesday: The upper-level ridge offshore will remain the dominant weather influence for most of the week.
Models do generally show it retrograding a bit Wednesday through Friday, which would open the door for weak shortwaves to slide through the Pacific Northwest. As of the latest model runs, none of these seem strong enough to result in precipitation or a push of strong winds though, continuing the risk for stratus and fog.

By the end of the weekend into early next week, around 60% of model ensembles between the GEFS/EPS/GEPS begin to hint at a brief break of the blocking pattern as a series of systems work to flatten the upper-level ridge and eventually kick it eastward. This will bring increasing chances for precipitation (15% across central Washington up to 50% over the mountains)
during the Sunday to Tuesday timeframe. The National Blend of Models (NBM) gives the mountains a 70% chance for one inch of snow from 4AM Saturday through 4AM Tuesday and a 20 to 30% chance for 1 inch across far eastern Washington and the North Idaho valleys. /vmt

AVIATION
00Z TAFs: The forecast largely continues persistence with widespread low stratus expected to remain in place under a strong upper-level ridge. Conditions will fluctuate between MVFR and IFR with light winds. Model probabilities are showing a 70% chance for improvement at KPUW/KLWS/KCOE around 21/22Z, but the confidence as stratus tends to be hard to scour out if there isn't a strong kicker, like a drier strong push.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in MVFR conditions or worse through the period. Low confidence in clearing occurring at KPUW/KLWS this afternoon.

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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 25 36 22 34 23 35 / 0 0 0 0 0 0 Coeur d'Alene 25 36 22 35 23 35 / 0 0 0 0 0 0 Pullman 26 38 24 37 25 36 / 0 0 0 0 0 0 Lewiston 27 40 26 39 28 39 / 0 0 0 0 0 0 Colville 22 37 19 34 21 36 / 0 0 0 0 0 0 Sandpoint 25 35 22 33 23 33 / 0 0 0 0 0 0 Kellogg 27 38 24 36 25 36 / 0 0 0 0 0 0 Moses Lake 25 38 21 37 23 36 / 0 0 0 0 0 0 Wenatchee 26 37 24 37 26 37 / 0 0 0 0 0 0 Omak 25 38 23 36 25 36 / 0 0 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Air Stagnation Advisory until 4 PM PST Tuesday for Central Chelan County-Moses Lake Area-Northeast Mountains- Okanogan Highlands-Okanogan Valley-Spokane Area-Upper Columbia Basin-Waterville Plateau-Wenatchee Area-Western Chelan County-Western Okanogan County.
ID...Air Stagnation Advisory until 4 PM PST Tuesday for Central Panhandle Mountains-Coeur d'Alene Area-Lewis and Southern Nez Perce Counties-Lewiston Area-Northern Panhandle.