High clouds associated with a warm frontal system is draped from the central Cascades and north this morning with clear conditoins further south. An upper level ridge currently along the West Coast will slide inland today. As the ridge amplifies over our region it will push the warm front north, leading to a sunny day across the region with a few caveats. Areas of low clouds along the eastern slopes of the Cascades formed overnight and will slow to burn off today. Low clouds near the Cascade Passes pulled through by easterly flow likely won't stick around all day with sunshine on the upper slopes.
The ridge will lead to rising freezing levels; near the Washington and Oregon coast at 4 am this morning free-air freezing levels were recorded at 8000' (Forks) and 9200' (Salem) respectively. This will lead to mild freezing levels for the Olymipcs and for areas well west of the Cascade crest like Mt Baker and Paradise, MRNP. The closer to the Cascade crest and along the east slopes of the Cascades and Mt Hood, the milder air will battle cool E-SE winds. Strong temperature inversions will occur with above-freezing air punching in above 5000-6000' to different degrees during the day and cooler temperatures along lower slopes. The northeaset Cascades will see the most muted warming trend relative to the rest of the region.
This pattern will hold overnight as a weak front approaches the coast around daybreak Monday. A trailing shortwave will help kick the weak N-S oriented front through on Monday, with light precipitation reaching the Cascades by mid-day. Snow levels will lower rapidly with the onset of precipitation and temperature inversions will begin to mix out as westerly winds move in late in the day and Monday night.
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 with a few high clouds.
Sunday
Night
Mostly clear in the evening, then mostly cloudy after midnight.
Sunday
Cloudy in the morning, then becoming mostly sunny with a few high clouds by late morning.
Sunday
Night
Mostly clear, high clouds increasing after midnight.
Sunday
Mostly cloudy in the morning, then quickly becoming mostly sunny with a few high clouds. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear, high clouds increasing after midnight.
Sunday
Mostly sunny with a few high clouds. Moderate to locally strong E-SE winds. Cooler Crystal and White Pass areas, milder Paradise and St Helens. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear, high clouds increasing late.
Sunday
Low clouds scattering slowly this morning, then mostly sunny with a few high clouds. Moderate to occasionally strong east-southeast winds both at ridgeline and Pass level. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear, high clouds increasing late.
Sunday
Low clouds scattering slowly this morning, then mostly sunny with a few high clouds. Moderate to strong east-southeast winds both at ridgeline and Pass level. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear, high clouds increasing late.
Sunday
Cloudy in the morning, then becoming mostly sunny with a few high clouds by late morning. Areas of low clouds. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear.
Sunday
Mostly cloudy in the morning, then becoming mostly sunny with a few high clouds by late morning. Areas of low clouds. Milder upper slopes, cooler lower slopes. Moderate to locally strong ridgeline winds in the afternoon.
Sunday
Night
Mostly clear.
Sunday
Mostly sunny with a few high clouds. Areas of low clouds. Milder upper slopes, cooler lower slopes.
Sunday
Night
Mostly clear.
Sunday
Mostly sunny with a few high clouds. Milder west side of the mountain, cooler east side and lower slopes. Locally moderate E-SE 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).