A trough lingers early Wednesday morning behind a frontal system that passed through the region Wednesday night. 5000 ft temperatures have cooled sharply into the upper 10s and low 20s across the region. Most of the shower activity will be light and decreasing as the trough exits to our east and W winds decrease. However, a convergence zone continues to bring some moderate snow to the I-90 corridor. That too should ease by mid-morning. The west slopes of the Cascades can expect up to 3" of additional low-density snow with minimal spillover east of the Cascade Crest. As the snow showers ease, expect increasing sun breaks throughout the day with more sun than clouds both east of the Cascade Crest and in the Olympics. Strong ridgeline winds continue to buffet the Mt. Hood area, but should ramp down rapidly during the morning hours. Moderate to strong ridgeline winds east of the Cascade Crest should also slowly decrease.
A weak ridge between systems should bring fair weather with light winds and cold temperatures on Thursday night. In the early morning hours, clouds begin to increase ahead of the next system dropping SE toward our region.
Light rain and snow gradually spread into NW Washington on Friday with snow levels remaining low. Ridgeline winds also increase into the moderate range. Further south and east, temperatures should be somewhat milder and more typical of April with freezing levels around 5500 ft for Mt. Hood.
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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Thursday
A few snow flurries early then scattered clouds.
Thursday
Night
Scattered clouds.
Thursday
Mostly cloudy with snow showers gradually decreasing.
Thursday
Night
Scattered clouds in the evening with increasing clouds after midnight.
Thursday
Decreasing light snow showers with mostly cloudy skies.
Thursday
Night
Scattered clouds in the evening with increasing clouds after midnight.
Thursday
Mostly cloudy skies with decreasing light snow showers.
Thursday
Night
Partly cloudy.
Thursday
Decreasing light snow showers with mostly cloudy skies. Decreasing light W wind at the Pass.
Thursday
Night
Partly cloudy. Light W wind at the Pass.
Thursday
Convergence lingering into the mid-morning hours with periods of moderate snow, then decreasing light snow showers. Sun breaks likely in the afternoon. Decreasing light to occasionally moderate W wind at the Pass.
Thursday
Night
Partly cloudy. Light W wind at the Pass.
Thursday
Partly cloudy with light snow showers at times near the Cascade Crest. Clearing skies further east.
Thursday
Night
Increasing clouds.
Thursday
Partly cloudy with light snow showers at times near the Cascade Crest. Clearing skies further east.
Thursday
Night
Partly cloudy.
Thursday
Partly cloudy with a chance of light snow showers.
Thursday
Night
Mostly clear.
Thursday
Light snow showers decreasing during the morning hours with strong ridgeline winds gradually easing. Partially clearing skies during the afternoon.
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).