We're in for a stormy day as a frontal system currently over northern Vancouver Island/central B.C. slowly slides south over the next 24 hours. The heaviest precipitation today will target the west slopes of the Cascades from about Hwy 2 and northward as well as the SW slopes of the Olympics. Areas further south will seem light to moderate precipitation this morning increasing in the afternoon. Precipitation will be lighter for east slopes of the Cascades south of Hwy2. Snow levels will inch upwards today, reaching around 4000-4500' in the north and 4500-5000' in the central, and 5000-5500' in the southern portions of the forecast area. If you're not currently experiencing rain at Pass level, the rain line should get there by the end of the day for the major Cascade Passes. Strong SW ridgeline winds will become extreme in the alpine.
This stormy trend will continue overnight with a strong cold front approaching through from NW. The frontal passage will occur for the central Cascades around midnight and reach Mt Hood before daybreak. Heavier precipitation and strong to extreme winds will become showers on Thursday with more moderate WSW winds. There will be a cold and unstable air mass overhead and we'll see showers continue to pepper the area, especially the west slopes of the Cascades. Convective showers will bring bouts of graupel as well as snow with snow levels hovering around 2000'.
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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Wednesday
Stormy with strong to extreme winds and light to moderate rain and snow. Heavier precipitation southwest slopes of the Olympics.
Wednesday
Night
Stormy with strong to extreme winds and light to moderate rain and snow in the evening, then becoming light to occasionally moderate showers with moderate ridgeline winds.
Wednesday
Stormy with moderate to heavy rain and snow and strong to ridgeline extreme winds.
Wednesday
Night
Stormy with moderate to heavy rain and snow through midnight and strong ridgeline winds, then becoming light to occasionally moderate showers with moderate ridgeline winds.
Wednesday
Stormy with moderate to heavy rain and snow and strong to extreme ridgeline winds.
Wednesday
Night
Stormy with moderate to heavy rain and snow through midnight and strong ridgeline winds, then becoming light to occasionally moderate showers with moderate ridgeline winds.
Wednesday
Stormy with moderate rain and snow, occasionally heavy Paradise area, and strong ridgeline winds. Precipitation heavier in the afternoon.
Wednesday
Night
Stormy with moderate to occasionally heavy rain and snow and strong ridgeline winds, then becoming light to moderate showers with moderate ridgeline winds after midnight.
Wednesday
Stormy with light to occasionally moderate rain and snow, becoming heavier in the afternoon. Strong west winds at ridgeline and Pass level.
Wednesday
Night
Stormy with moderate to heavy rain and snow through midnight and strong ridgeline winds, then becoming light to moderate showers with moderate W ridgeline and Pass level winds.
Wednesday
Stormy with light to moderate rain and snow, becoming heavier in the afternoon. Strong west winds at ridgeline and Pass level.
Wednesday
Night
Stormy with moderate to heavy rain and snow through midnight and strong ridgeline winds, then becoming light to moderate showers with moderate W ridgeline and Pass level winds.
Wednesday
Stormy with light to occasionally moderate rain and snow, becoming heavier in the afternoon. Much lighter precipitation further east of the Cascade crest. Strong ridgeline winds.
Wednesday
Night
Stormy with light to moderate rain and snow and strong ridgeline winds, heaviest near the Cascade crest, then becoming light showers late overnight along with decreasing winds.
Wednesday
Stormy with light to occasionally moderate rain and snow, becoming heavier in the afternoon. Much lighter precipitation further east of the Cascade crest. Strong ridgeline winds.
Wednesday
Night
Stormy with light to moderate rain and snow and strong ridgeline winds, heaviest near the Cascade crest, then becoming light showers late overnight along with decreasing winds.
Wednesday
Light to occasionally moderate rain and snow, becoming heavier in the afternoon. Much lighter precipitation further east of the Cascade crest. Strong ridgeline winds.
Wednesday
Night
Stormy with light to moderate rain and snow and strong ridgeline winds, heaviest near the Cascade crest, then becoming light showers late overnight along with decreasing winds.
Wednesday
Stormy with light to moderate rain and snow, becoming heavier in the afternoon. Strong to extreme ridgeline winds.
Wednesday
Night
Stormy with moderate to occasionally heavy rain and snow. Strong to extreme 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).