Weak warm frontal moisture has started to push inland this morning with a few flurries for the west slopes of the Cascades and steadier snow over the Olympic mountains. The main frontal boundary from a closed low well offshore will approach but never push inland today as it drops southward along the coast. However, warm frontal moisture should lift NE across the forecast area Friday evening, and spread light snow to the central and northern Cascades. There's quite a bit of uncertainty regarding the extent of light snow Friday night, with higher confidence that it will be light. E-SE winds will begin to ramp up this afternoon and become moderate in many areas.
It will be a different story for the Olympics Friday and Friday night, where winds will be stronger and an upslope component will help enhance snowfall on the southern and eastern side of the range. Hurricane Ridge will see snow, but will not be favored for the heaviest snowfall in this pattern.
On Saturday, the low will pull further south and our area will begin to dry out. However, with surface high pressure to our north, lower pressure offshore, expect east winds to increase during the day. This will help pull colder air through the Passes and east of the Cascade crest in general. For areas well west of the Cascade crest, expect a warming trend on Saturday.
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
Light snow. Moderate to occasionally strong ridgeline winds.
Friday
Night
Light to moderate snow tapering off after midnight. Strong ridgeline winds.
Friday
Cloudy with periods of light snow. Increasing ridgeline winds.
Friday
Night
Cloudy with light snow. Moderate to occasionally strong ridgeline winds.
Friday
Cloudy with periods of light snow.
Friday
Night
Cloudy with light snow.
Friday
Cloudy with periods of light snow.
Friday
Night
Cloudy with periods of light snow. Moderate ridgeline winds.
Friday
Cloudy with a few flurries today. Light east winds increasing and becoming light to moderate both at Pass level and ridgeline in the afternoon.
Friday
Night
Cloudy with periods of light snow. Moderate east winds both at Pass level and along ridgelines.
Friday
Cloudy with a few flurries today. Light east winds increasing and becoming light to moderate both at Pass level and ridgeline in the afternoon.
Friday
Night
Cloudy with periods of light snow. Moderate east winds both at Pass level and along ridgelines.
Friday
Partly cloudy, becoming cloudy later this morning with increasing high clouds.
Friday
Night
Cloudy with periods of light snow.
Friday
Partly cloudy, becoming cloudy later this morning with increasing high clouds.
Friday
Night
Cloudy with periods of light snow.
Friday
Partly cloudy, becoming cloudy later this morning with increasing high clouds.
Friday
Night
Cloudy. Moderate ridgeline winds.
Friday
Partly cloudy, becoming cloudy later this morning with increasing high clouds.
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).