A weak frontal system will lift north over the area today, bringing glancing periods of light precipitation (mostly rain) to areas south of Hwy 2 and steadier, but still relatively light rain to the northwest Cascades and the Olympics, especially in the afternoon. Snow levels will be high, 8,000-10,000' as we inch towards the winter solstice. Easterly flow is present, but there's not much cold air to nudge snow levels lower in the Cascade Passes. There's a slight chance of a wintry mix along the east slopes of the Cascades, anywhere pockets of low level sub-freezing air and light precipitation occur today. Most areas can expect moderate southerly ridgeline winds, except strong for the Olympics and northwest Cascades.
Light rain showers will linger for the northwest Cascades and Olympics through the early evening hours. Otherwise we'll see a mainly dry Friday night with elevated snow levels. SE winds will begin to ramp up late tonight, becoming strong before sunrise as another frontal system approaches.
We'll start off Saturday warm and windy with a slightly stronger frontal system pushing inland mid-day. Expect a switch from breezy to strong, E or SE winds to W-SW in the afternoon with a frontal passage. Snow levels will fall quickly with the onset of precipitation and settle around 4000' Saturday afternoon. This won't be a big storm, most WE totals on Saturday will be around 0.25" or less.
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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Friday
Cloudy with periods of light rain, becoming light to occasionally moderate in the afternoon. Strong ridgeline winds.
Friday
Night
Mostly cloudy with light rain showers in the evening, then partly to mostly cloudy. Light to occasionally moderate ridgeline winds.
Friday
Cloudy with periods of light rain, becoming light to occasionally moderate in the afternoon. Strong ridgeline winds.
Friday
Night
Mostly cloudy with light rain showers in the evening, then partly to mostly cloudy. Light to occasionally moderate ridgeline winds.
Friday
Cloudy with periods of light rain, increasing slightly in the afternoon. Light to occasionally moderate ridgeline winds.
Friday
Night
Mostly cloudy with a chance of light rain showers in the evening, then partly to mostly cloudy. Light ridgeline winds to moderate overnight.
Friday
Cloudy with periods of light rain. Moderate ridgeline winds.
Friday
Night
Partly to mostly cloudy. Light ridgeline winds to moderate overnight.
Friday
Cloudy with periods of light rain. Light to moderate S ridgeline and E Pass level winds.
Friday
Night
Partly to mostly cloudy. Increasing moderate SE ridgeline and E Pass level winds overnight.
Friday
Cloudy with periods of light rain. Moderate S ridgeline and E Pass level winds.
Friday
Night
Partly to mostly cloudy. Increasing moderate SE ridgeline and E Pass level winds overnight.
Friday
Cloudy. Chance of a light wintry mix. Moderate ridgeline winds.
Friday
Night
Partly to mostly cloudy. Light ridgeline winds increasing to moderate after midnight.
Friday
Cloudy. Chance of a light wintry mix. Moderate ridgeline winds.
Friday
Night
Partly to mostly cloudy. Light ridgeline winds increasing to moderate after midnight.
Friday
Cloudy. Chance of light rain, mainly in the morning. Moderate ridgeline winds.
Friday
Night
Partly to mostly cloudy. Light ridgeline winds increasing to moderate after midnight.
Friday
Cloudy. Chance of light rain, mainly in the morning. Moderate ridgeline winds.
Friday
Night
Partly to mostly cloudy. Light ridgeline winds increasing to moderate after midnight.
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).