A trough exits the region today as an offshore ridge edges into the region. Very light snow showers and weak convergence dwindling quickly along the Cascades west slopes foothills to start the day. Most areas will experience cooler-than-average weather with highs in the 20s. Moderate WNW ridgeline winds for Mt. Hood and the Cascade Crest areas south of I-90 should decrease throughout the day but will continue to trap some low clouds west of the Cascades with drying downslope winds producing mostly sunny skies east of the Crest.
The high-pressure gains increased influence Sunday night, but a weakening frontal boundary riding over the top of it will keep it relatively flat. Increased high clouds spread into the region with 5000 ft temperatures in the upper 10s to mid 20s.
Monday starts chilly. The weak front passing through during the morning could bring a dusting to 2" of snow to the west slopes of the Olympics and the Cascades from Snoqualmie Pass northward. The region dries out with freezing levels rising to seasonal norms (2500-5000 ft) by the afternoon with more sunshine as the offshore ridge rebounds.
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
Partly cloudy to mostly sunny.
Sunday
Night
Partly cloudy with clouds increasing overnight.
Sunday
Partly cloudy.
Sunday
Night
Partly cloudy.
Sunday
Partly cloudy.
Sunday
Night
Partly cloudy.
Sunday
Partly cloudy with some light snow showers early and periods of full sunshine during the afternoon.
Sunday
Night
Partly cloudy to mostly clear.
Sunday
Partly cloudy with a few snow showers possible west of the Pass, early in the day. Decreasing light ridgeline and W wind at the Pass.
Sunday
Night
Partly cloudy. Light ridgeline and W or variable wind at the Pass.
Sunday
Partly cloudy with a few snow showers possible west of the Pass, early in the day. Decreasing light to moderate ridgeline and light W wind at the Pass.
Sunday
Night
Partly cloudy. Light ridgeline and W or variable wind at the Pass.
Sunday
Mostly sunny.
Sunday
Night
Mostly clear with high clouds increasing.
Sunday
Mostly sunny.
Sunday
Night
Mostly clear with high clouds increasing.
Sunday
Mostly sunny.
Sunday
Night
Mostly clear with high clouds increasing.
Sunday
Mostly cloudy with snow showers tapering along the west slopes of Mt. Hood early in the day. Partly cloudy to mostly sunny on the eastern side. Decreasing 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).