A transient weak ridge gives our region a mostly dry day on Friday. Temperatures start the day frigid. Washington Pass dropped below 0F overnight while many 5000 ft locations were in the 10s this morning. Temperatures at this elevation generally rise into the mid 20s by the afternoon. A deck of clouds around 6000 ft has banked up against the west slopes of the southern Cascades and should gradually shift northward during the day, leaving more sunny skies in the south by the afternoon. Low-level winds shift E early Friday and gradually increase with time, while ridgeline winds remain mostly light out of the W.
Friday night, a deep low drops south from the Gulf of Alaska. Light snow develops ahead of a strengthening surface low rotating north of the Oregon Coast.
That low deepens and brings increasing moderate ESE winds to areas near the Cascade Crest, while areas away from the Crest experience increasing southerly winds. As a warm front lifts northward, expect light to moderate snow to develop and spread into the southern Cascades early Saturday, the central Washington Cascades before 10 AM, and then expand throughout the region. Snow levels gradually rise but remain well below the Passes.
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
Mostly cloudy with isolated snow showers on the south slopes.
Friday
Night
Light snow for the southern and eastern Olympics, otherwise mostly cloudy skies.
Friday
Mostly cloudy,
Friday
Night
Mostly cloudy with a chance of light snow.
Friday
Mostly cloudy.
Friday
Night
Mostly cloudy.
Friday
Mostly cloudy.
Friday
Night
Mostly cloudy.
Friday
Mostly cloudy. Light ridgeline and variable winds switch E at the Pass.
Friday
Night
Mostly cloudy. Increasing light ridgeline and E winds at the Pass.
Friday
Mostly cloudy. Light ridgeline and variable winds switch E at the Pass.
Friday
Night
Mostly cloudy. Increasing light to moderate ridgeline and mostly light E winds at the Pass.
Friday
Partly cloudy.
Friday
Night
Mostly cloudy with isolated snow flurries.
Friday
Partly cloudy.
Friday
Night
Mostly cloudy with a chance of light upslope snowfall developing.
Friday
Partly cloudy.
Friday
Night
Mostly cloudy with occasional snow flurries.
Friday
Mostly cloudy with occasional snow flurries.
Friday
Night
Mostly cloudy with light snow developing in the early morning hours.
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).