We're in for another stellar dry and mostly sunny day across the region under high pressure. We'll see a few high clouds creep in from the west towards the end of the day, especially over the Olympics. High and mid clouds will increase Sunday night as a weak weather system approaches. Freezing levels will be variable, as is typical under high pressure in winter. Freezing levels will be higher west of the Cascade crest and for Mt Hood, in the 5000-7000' range. Near the Cascade Passes and along the eastern slopes of the Cascades, expect freezing levels closer to the surface, with the coldest temperatures at low elevations and in the valleys due to temperature inversions. There should be some patchy low clouds along the east slopes of the Cascades and to the east of the Cascade Passes, but nothing like the widespread stratus from earlier in the week.
The aforementioned weak upper trough will pass through on Monday. We don't expect any precipitation with this system, but there should be a fair amount of cloud cover. A period of westerly winds will also help stir up the lower atmosphere, and freezing levels should be a more uniform 4000-6000' across the Cascades in the afternoon.
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
Mostly sunny in the morning, then partly to mostly sunny in the afternoon with increasing high clouds. Light ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny with a few high clouds in the afternoon. Light to occasionally moderate ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny with a few high clouds in the afternoon. Light ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny with a few high clouds in the afternoon. Patchy morning valley low clouds near and east of White Pass. Cooler lower slopes and eastern parts of the zone like White Pass. Light ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny with a few high clouds in the afternoon. Patchy morning valley low clouds near and east of the Pass. Light to moderate E winds at Pass level, light W ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds.Light E winds at Pass level, light to moderate W ridgeline winds.
Sunday
Mostly sunny with a few high clouds in the afternoon. Patchy morning valley low clouds near and east of the Pass. Light to moderate E winds at Pass level, light W ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate E winds at Pass level, light to moderate W ridgeline winds.
Sunday
Mostly sunny. Patchy morning valley low clouds. Light to occasionally moderate ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny. Patchy morning valley low clouds. Light to occasionally moderate ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny. Patchy morning valley low clouds. Light to occasionally moderate ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate ridgeline winds.
Sunday
Mostly sunny. Light to occasionally moderate ridgeline winds.
Sunday
Night
Partly cloudy in the evening, then mostly cloudy after midnight with increasing high and mid clouds. Light to moderate 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).