Brrr...an unseasonably cold upper level trough has set up over the western US and temperatures aren't done sliding down over the short term. A modified arctic front came through last night and brought a few inches of snow, most notably in the Mission Ridge area as it passed from the interior and pressed along the east side of the Cascades. Washington State is experiencing E or NE offshore flow while on the southern periphery of the counter-clockwise circulation located off of the Washington Coast, Mt Hood continues to see light snow showers rotated in westerly flow. We'll see light snow showers along the Olympics, east slopes of the Cascades and Cascade Passes today and more scattered snow showers elsewhere. The Olymipcs are closest to the low pressure offshore and may pick up the most new snow over the next 36 hours. Winds with be in the light to moderate range today with localized breezy NE winds near the Fraser River Valley Outflow and E winds elsewhere.
Expect more of the same tonight except that the offshore flow and easterly winds will increase to moderate, becoming locally strong near Snoqualmie Pass and southward for areas including Crystal Mt, White Pass and Mt. Hood. We'll see a reinforcing shot of cold air, with overnight mid-mountain lows falling well into single digits and even lower wind chills. It's likely we'll see some below 0F temperatures at higher elevation sites tomorrow morning.
On Thursday, the low complex positioned off the mouth of the Columbia River will drop south, pulling the moisture with it. We may see some mid-day/afternoon sunshine following the thinning of low and mid-level clouds on Thursday afternoon especially near and west of the Cascade crest. Moderate east winds and cold temperatures will continue on Thursday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Wednesday
Cloudy with light snow showers.
Wednesday
Night
Cloudy with light snow showers. Moderate ridgeline winds.
Wednesday
Cloudy with scattered light snow showers. Localized moderate NE ridgeline winds.
Wednesday
Night
Cloudy with a few flurries. Moderate ridgeline winds.
Wednesday
Cloudy with scattered light snow showers.
Wednesday
Night
Cloudy with a few flurries. Moderate ridgeline winds.
Wednesday
Cloudy with scattered light snow showers. Ridgeline winds becoming moderate in the afternoon.
Wednesday
Night
Cloudy with scattered light snow showers. Moderate to strong ridgeline winds.
Wednesday
Cloudy with occasional periods of light snow. Light E winds at Pass level and ridgeline increasing to light to moderate in the afternoon.
Wednesday
Night
Cloudy with occasional periods of light snow. Moderate to strong ridgeline and Pass level E winds.
Wednesday
Cloudy with occasional periods of light snow. Light to moderate E winds at Pass level and ridgeline increasing slightly in the afternoon.
Wednesday
Night
Cloudy with occasional periods of light snow. Moderate to strong ridgeline and Pass level E winds.
Wednesday
Cloudy with occasional periods of light snow. Light to moderate ridgeline winds.
Wednesday
Night
Cloudy with occasional periods of light snow. Moderate ridgeline winds.
Wednesday
Cloudy with occasional periods of light snow. Moderate ridgeline winds.
Wednesday
Night
Cloudy with occasional periods of light snow. Moderate ridgeline winds.
Wednesday
Cloudy with occasional periods of light snow. Light to moderate ridgeline winds.
Wednesday
Night
Cloudy with occasional periods of light snow. Moderate ridgeline winds.
Wednesday
Cloudy with scattered light snow showers. Light to moderate ridgeline winds.
Wednesday
Night
Cloudy with scattered light snow showers. Moderate to strong ridgeline winds.
The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.
The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.
The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.
*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.
Ridgeline winds are the average wind speed and direction over a 6 hr time period.
The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.
Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.
Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).