A deep, cold upper-level low in the Gulf of Alaska shifts southward over the course of the next 5 days. A strong cold front will move toward our region from the northwest, at the leading edge of this region of low pressure.
With cold air in place, pre-frontal increasing light to moderate snowfall will increase in coverage across the region on Friday. Expect 2-6" of snow to fall near and west of the Cascade Crest with 1-2" further east. Winds will also increase into the moderate range by Friday afternoon.
The occluded frontal system moves to the PNW coastline by early Saturday morning, bringing very stormy conditions with increasing heavy snowfall and increasing moderate to strong SW winds (extreme possible at Mt. Hood). A wintry mix in the early morning hours at Snoqualmie Pass as a warm sector of the storm brings in a sliver of milder air, but significant accumulations remain on track above 3500 ft. The wintry mix could change to rain briefly (extending to the east slopes of the Cascades below 3500 ft) as the cold front passage cuts off a period of E flow cuts and snow levels temporarily rise. Moderate snow showers follow later Saturday morning with cooling behind the front. However, the southern Cascades should continue the heavy snowfall through much of the day on Saturday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Friday
Cloudy with light snow developing in the late morning hours and increasing in the afternoon.
Friday
Night
Heavy snow becoming very heavy and mixing with rain below 4000 ft after midnight. Moderate to strong ridgeline winds.
Friday
Light snow showers in the morning with increasing light to moderate snow in the afternoon.
Friday
Night
Heavy snow in the evening becoming very heavy after midnight. Strong ridgeline winds.
Friday
Light snow in the morning becoming moderate in the afternoon.
Friday
Night
Moderate to heavy snow in the evening, becoming very heavy overnight. Strong ridgeline winds.
Friday
Light snow in the morning becoming moderate in the afternoon at Paradise. Increasing light snow for Crystal and White Pass.
Friday
Night
Increasing heavy snow at Paradise. Light snow becoming heavy overnight at Crystal. Increasing light to moderate snow at White Pass. Strong ridgeline winds.
Friday
Increasing light snow. Increasing light W wind through the Pass, becoming moderate by the end of the day.
Friday
Night
Moderate snow in the evening, becoming heavy overnight. Light to moderate variable, then E wind at the Pass.
Friday
Light snow in the morning becoming moderate in the afternoon. Increasing light W wind through the Pass, becoming moderate by the end of the day.
Friday
Night
Increasing heavy snow. Light to moderate variable, then E wind at the Pass.
Friday
Periods of light snow, increasing in the afternoon.
Friday
Night
Light snow in the evening becoming heavy overnight.
Friday
Periods of light snow, increasing in the afternoon.
Friday
Night
Light snow in the evening becoming moderate to heavy overnight.
Friday
Periods of light snow, increasing in the afternoon.
Friday
Night
Increasing light snow.
Friday
Light snow showers change to light to moderate snow from mid-morning onwards. Increasing moderate to strong ridgeline winds.
Friday
Night
Increasing light to moderate 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).