0815 Update: Sunnier this morning Cascades and Mt Hood
A frontal system is approaching the Washington coast this morning with radar returns just starting to show up over the Olympic peninsula. The front's timing has slowed by 2-3 hrs, versus yesterday's forecast, with the frontal passage now expected for the central Cascades in the 2-3 pm timeframe. We'll see increasing cloud cover today with precipitation moving this morning for the Olympics and the Cascades just before or near mid-day. S-SE winds have increased out ahead of the front with strong winds expected in the Hurricane Ridge, Mt Baker and Crystal areas. It's a mixed bag of temperatures and freezing levels out there with some milder air at mid/upper elevations, but once the precipitation starts snow levels should quickly fall to 3000' by mid-afternoon and continue sliding down in the late afternoon and evening.
The switch to strong westerly winds has also been pushed back to mid/late afternoon as well. Strong westerly winds for the central/south Cascades and Mt Hood will continue overnight and become more NW-erly. There's an unusual amount of uncertainty regarding the post-frontal precipitation forecast Saturday night, but a messy consensus suggests the central-west and southwest Cascades will pick up the most overnight with the potential for a Puget Sound Convergence zone. Through early Sunday morning, 4-12" of snow seems reasonable for the west slopes of the Cascades and Mt Hood with lower amounts over the Olympics and east slopes of the Cascades.
We should see showers taper down on Sunday with decreasing but still breezy NW ridgeline winds. Expect broken clouds along the west slopes of the Cascades in the afternoon and more sunshine on the east-side of the Cascades.
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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Saturday
Cloudy with light rain and snow developing becoming light to moderate midday and then light snow showers in the afternoon. Strong ridgeline winds.
Saturday
Night
Mostly cloudy with scattered light snow showers. Moderate ridgeline winds.
Saturday
Mostly cloudy early this morning with light snow developing late morning and becoming moderate snow midday. Strong ridgeline winds.
Saturday
Night
Cloudy with light to occasionally moderate snow showers. Moderate ridgeline winds.
Saturday
Partly sunny early this morning with light snow developing late morning and becoming light to occasionally moderate snow midday. Moderate ridgeline winds.
Saturday
Night
Cloudy with light to moderate snow showers. Moderate ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate to strong ridgeline winds.
Saturday
Night
Cloudy with light to moderate snow showers. Moderate to strong ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate SE-E Pass level and ridgeline winds becoming strong West winds late.
Saturday
Night
Cloudy with light to moderate snow showers. Moderate to strong West Pass level and ridgeline winds.
Saturday
Partly to mostly cloudy early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate SE-E Pass level and ridgeline winds becoming strong West winds late.
Saturday
Night
Cloudy with light to moderate snow showers. Moderate to strong West Pass level and ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate winds increasing in the afternoon.
Saturday
Night
Cloudy with occasional light snow showers. Moderate ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate winds becoming strong in the afternoon.
Saturday
Night
Cloudy with light snow showers. Strong ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate winds becoming strong in the afternoon.
Saturday
Night
Cloudy with occasional light snow showers. Moderate to strong ridgeline winds.
Saturday
Mostly sunny early this morning, then cloudy with light snow developing around mid-day and becoming light to occasionally moderate snow early afternoon. Moderate winds becoming strong in the afternoon.
Saturday
Night
Cloudy with light to moderate 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).