A weak frontal boundary is bringing a surprise round of rain this morning to the Olympics and the Cascades near and especially west of the crest. However, the main precipitation is still slotted to arrive this afternoon, with a focus on the Olympics, and the west slopes of the Cascades,with more moderate precipitation likely for the west slope volcanoes before 5pm. This will be mostly a rain event, with snow levels only falling to 7500' during the day. South winds will increase today as well, becoming strong over the Olympics and Mt Baker area. The east slopes of the Cascades will likely see some sun breaks this morning before clouds fill in.
A trailing shortwave trough will kick the frontal boundary inland tonight and spread precipitation over the east slopes of the Cascades. Look for a heavier shot of precipitation once again for the volcanoes with up to an inch of water (!) overnight. Snow levels will slowly fall to 5000-5500' by morning. The Wentachees could pick up a decent shot of precipitation in this more southerly flow pattern.
On Monday, we'll see a new upper level feature reinvigorating showers in the afternoon, particularly over the Olympics, southern WA Cascades and Mt Hood. Snow levels will hover around 5000', except slightly warmer along the east slopes 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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Sunday
Light to moderate rain, heaviest southern slopes of the Olympics. Moderate ridgeline winds, becoming strong in the afternoon.
Sunday
Night
Moderate to occasionally heavy rain and snow, heaviest southern slopes of the Olympics. Moderate to strong ridgeline winds.
Sunday
Cloudy this morning with periods of light rain, then light to moderate rain and high elevation snow in the afternoon. Moderate ridgeline winds, becoming strong in the afternoon.
Sunday
Night
Moderate to occasionally heavy rain and snow. Moderate to strong ridgeline winds.
Sunday
Cloudy this morning with periods of light rain, then light to occasionally moderate rain and high elevation snow in the afternoon. Moderate ridgeline winds.
Sunday
Night
Moderate to occasionally heavy rain and snow. Moderate ridgeline winds.
Sunday
Cloudy this morning with periods of light rain, then light to moderate rain and high elevation snow in the afternoon. Moderate ridgeline winds.
Sunday
Night
Moderate to occasionally heavy rain and snow. Moderate ridgeline winds.
Sunday
Mostly cloudy with periods of light rain this morning, then becoming cloudy with light rain and high elevation snow developing in the afternoon. Light to moderate SE ridgeline winds and light E winds at Pass level.
Sunday
Night
Moderate rain and snow. Moderate ridgeline winds. Light to moderate SW ridgeline winds and W winds at Pass level.
Sunday
Mostly cloudy with periods of light rain this morning, then becoming cloudy with light rain and high elevation snow developing in the afternoon. Light to moderate SE ridgeline winds and light E winds at Pass level.
Sunday
Night
Moderate rain and snow. Moderate ridgeline winds. Light to moderate SW ridgeline winds and W winds at Pass level.
Sunday
Partly to mostly cloudy this morning with a chance of rain. Becoming cloudy with light rain and high elevation snow developing in the afternoon. Light to moderate ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate ridgeline winds.
Sunday
Partly to mostly cloudy this morning with a chance of rain. Becoming cloudy with light rain and high elevation snow developing in the afternoon. Light to moderate ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate ridgeline winds.
Sunday
Partly to mostly cloudy this morning with a chance of rain. Becoming cloudy with light rain and high elevation snow developing in the afternoon. Light to moderate ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate ridgeline winds.
Sunday
Mostly cloudy with a few sunbreaks and a chance of light rain this morning, then becoming cloudy with light to occasionally moderate rain and high elevation snow developing in the afternoon. Moderate ridgeline winds.
Sunday
Night
Moderate to occasionally heavy rain and snow. 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).