A surface low near Mt. Hood shifts east of the Cascades by mid-morning. A broad band of light to moderate snowfall has a low-level upslope component across the east slopes of the Cascades from I-90 northward. This band drifts northward during the day. E low-level flow shifts W as the low moves into the Columbia Basin by mid-morning. Increasing light W winds become moderate in exposed areas near and E of the Cascade Crest by the afternoon. Expect light snow showers to increasingly focus on the west slopes of the Cascades. Shower activity may be moderate in convergence focused near Stevens or Snoqualmie Pass through the evening hours. Shower activity should decrease in the afternoon.
An upper low dropping down the British Columbia coastline, re-directing mostly light ridgeline winds SWerly on Saturday as light snow showers continue near and west of the Cascade Crest. Expect partial sunshine at times further east.
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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Friday
Light snow becoming showery.
Friday
Night
Very light snow showers.
Friday
Light to moderate snow becoming showery.
Friday
Night
Light snow showers.
Friday
Light snow transitions to showers.
Friday
Night
Light snow showers may be moderate at times in convergence.
Friday
Periods of light snow transitioning to snow showers.
Friday
Night
Light snow showers.
Friday
Light to moderate snow transitioning to light snow showers. Light to moderate ridgeline and light E winds shift W at the Pass.
Friday
Night
Light snow showers (moderate in convergence). Light to moderate ridgeline and light W winds at the Pass.
Friday
Light snow transitioning to light snow showers. Light to moderate ridgeline and light to moderate E winds shift W at the Pass early in the day.
Friday
Night
Light snow showers (moderate in convergence). Moderate ridgeline and light to moderate W winds at the Pass.
Friday
Light to moderate snow decreases in the afternoon.
Friday
Night
Light snow showers.
Friday
Light to moderate snow tapers to light snow showers by mid-morning.
Friday
Night
Light snow showers.
Friday
Periods of light snow or light snow showers.
Friday
Night
Light snow showers with partial clearing.
Friday
Light to moderate snow becomes showery. Ridgeline winds increase into the moderate range.
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).