Marine Weather and Tide Forecast for Lewiston, ID

SYNOPSIS
The Inland Northwest returns to a dry period today through Thursday. Valley fog and temperatures below freezing could result in slick roads through midweek. Active weather returns Friday into the weekend, with mountain snow and a mix of rain and snow in the valleys. Colder temperatures, with lowering snow levels for the latter half of the weekend into next week, will bring the potential for light lowland snow accumulations.

DISCUSSION
Tonight through Thursday: The region will be under a ridge pattern between Low pressure systems along the California coast and in the Gulf of Alaska. It leads to benign weather pattern for the Inland Northwest. Precip chances for the next few days is next to zero. While the air mass is drier, cooler temperatures and lingering moisture will lead to patchy fog in the mornings. Highs will be in the upper 30s and low 40s. Lows will be in the 20s and low 30s. Mid to upper level clouds could affect the highs and lows for the period.

Friday through Sunday: The Gulf of Alaska Low begins to press South and weaken the ridge pattern over the Pacific Northwest.
The ridge breakdown will allow for a trough to dig south along the coastline. The trough will be in place for the next several days. The Low will bring several waves of moisture and cooler air mass into the region. Ensembles are decent agreement for mountain snow and a wintry mix for the Basin and valleys. Precip amounts range 0.1-0.25 through the weekend. Snow amounts range from 1 to 4 inches for the mountain passes. Highs and lows will only see a few degree drop from earlier in the week. Highs will be in the 30s and low 40s. Lows will be in the 20s and low 30s.

Monday and Tuesday: With the trough pattern in place, a series of weak lows will move the region bringing several rounds of precip to the region. Snow chances continue for the mountains.
850MB temperatures will finally be below -3C. Heights will be below 540dm. It will lead to increased likely for increased snow chances for the Basin and valleys. /JDC

AVIATION
00Z TAFS: Dry, stable airmass will be over the region. VFR conditions expected for TAF sites through the period. Saturation in the boundary layer could produce patchy fog during the between 04-10Z. Confidence is low on impacting TAF sites.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions through the period. Low confidence in fog impacting TAF sites.

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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 28 44 27 41 29 41 / 0 0 0 0 0 0 Coeur d'Alene 28 44 27 42 29 42 / 0 0 0 0 0 0 Pullman 30 46 29 43 30 43 / 0 0 0 0 0 0 Lewiston 32 48 31 46 33 47 / 0 0 0 0 0 0 Colville 26 44 26 43 27 40 / 0 0 0 0 0 10 Sandpoint 28 42 27 40 29 39 / 0 0 0 0 0 10 Kellogg 29 45 29 43 30 41 / 0 0 0 0 0 10 Moses Lake 29 49 28 43 28 43 / 0 0 0 0 0 0 Wenatchee 31 46 32 43 32 43 / 0 0 0 0 0 0 Omak 29 45 31 43 31 41 / 0 0 0 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...None.
ID...None.