Light to moderate rain and snow in NW flow aloft will continue this morning across the area with the heaviest precipitation along the west slopes of the Cascades near and north of I-90 to the Canadian border. A low pressure system heading into the central B.C. coast this afternoon will begin to spread warm frontal precipitation further south this afternoon to the south Washington Cascades and eventually Mt Hood. Look for precipitation rates to rise this afternoon as well as a slight uptick in snow levels, a trend that will continue through the early evening. With snow levels ranging from 3500-5500', snowfall totals will be highly dependent on elevation as well as proximity to the Cascade crest during the daylight hours.
The trailing cold front will pass through the central Cascades this evening and we'll see steady rain and snow turn to moderate to locally heavy showers as snow level plummet after midnight. During the is time, most areas will experience strong WNW ridgeline winds. Winds will increase further Monday night out of the W behind the front, with many areas peaking in the extreme category.
Snow showers will continue on Tuesday as a cold upper level trough sits over the area and keeps convective showers going all day. Some showers will be heavy and we'll likely see periods of graupel mixed into the showers.
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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Monday
Periods of light rain or snow, increasing to light to occasionally moderate late in the afternoon. Strong ridgeline winds.
Monday
Night
Light to occasionally moderate rain and snow becoming light to moderate rain and snow showers late evening. Strong winds.
Monday
Light to moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Strong ridgeline winds in the afternoon.
Monday
Night
Moderate to heavy rain and snow becoming showers after midnight. Strong winds.
Monday
Moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Strong ridgeline winds.
Monday
Night
Moderate to heavy rain and snow becoming showers after midnight. Strong winds.
Monday
Light rain and snow becoming moderate in the afternoon, heaviest Paradise area. Strong ridgeline winds.
Monday
Night
Moderate to heavy rain and snow becoming showers after midnight. Strong winds.
Monday
Light to moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Strong W ridgeline and Pass level winds.
Monday
Night
Moderate to heavy rain and snow becoming showers after midnight. Strong W ridgeline and Pass level winds.
Monday
Light to moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Strong W ridgeline and Pass level winds.
Monday
Night
Moderate to heavy rain and snow becoming showers after midnight. Strong W ridgeline and Pass level winds.
Monday
Light to occasionally moderate rain and snow becoming moderate in the afternoon near the Cascade crest. Strong ridgeline winds.
Monday
Night
Moderate rain and snow becoming showers after midnight. Strong winds.
Monday
Light to occasionally moderate rain and snow becoming moderate in the afternoon near the Cascade crest. Strong ridgeline winds.
Monday
Night
Moderate rain and snow becoming showers after midnight. Strong to extreme winds.
Monday
Light to occasionally moderate rain and snow becoming moderate in the afternoon near the Cascade crest. Strong ridgeline winds.
Monday
Night
Moderate rain and snow becoming showers after midnight. Strong to extreme winds.
Monday
Periods of light rain or snow, increasing to light to moderate late in the afternoon. Strong ridgeline winds.
Monday
Night
Moderate rain and snow becoming showers after midnight. Strong to extreme 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).