Cold temperatures remain in place throughout the forecast period.
A closed low dropping SE toward the Oregon coast lifts a band of mostly light snowfall NE, impacting the southern Cascades and Olympics on Wednesday. Increasing light to moderate easterly low-level flow should peak during the afternoon bringing chilly winds through the mountain gaps. Combining the low-level flow with SE winds aloft should help squeeze out moisture along the east slopes of the Cascades from around highway 2 southward.
The upper low moves onshore Wednesday night. Light snowfall should decrease from north to south across the region. Easterly low-level flow decreases into the light range. Temperatures should be cold, particularly in areas that see some clearing skies (most likely in the North Cascades).
Most areas could see 1-4" with this storm, with slightly heavier amounts possible in the southern and eastern Olympics and Mt. Hood areas.
A weak shortwave trough moves in from the NW on Thursday, bringing an increase in light snow showers and very weak convergence focusing on the west slopes of the central Cascades. An additional 1-3" of snow could fall with this feature.
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
Increasing periods of light snow. Strong ridgeline wind gusts.
Wednesday
Night
Snow flurries or very light snow during the evening hours, then partial clearing overnight.
Wednesday
Periods of very light snow. Cold.
Wednesday
Night
Mostly cloudy in the evening with light snow possible overnight. Cold.
Wednesday
Cloudy. Cold.
Wednesday
Night
Mostly cloudy in the evening with light snow possible overnight. Cold.
Wednesday
Light snow developing.
Wednesday
Night
Cloudy. Cold.
Wednesday
Light snow is possible during the afternoon. Light E winds become moderate in the afternoon at the Pass.
Wednesday
Night
Light snow is possible at times. Moderate E winds become light at the Pass.
Wednesday
Light snow developing from late morning onwards. Light E winds become moderate in the afternoon at the Pass.
Wednesday
Night
Light snow at times. Moderate E winds become light at the Pass.
Wednesday
Cloudy with snow flurries possible.
Wednesday
Night
Mostly cloudy.
Wednesday
Cloudy with light snow developing from late morning onwards.
Wednesday
Night
Light snow tapering during the evening, then becoming cloudy with flurries.
Wednesday
Cloudy early with light snow developing around mid-morning slightly during the afternoon.
Wednesday
Night
Light snow tapering during the evening, then becoming cloudy with flurries.
Wednesday
Moderate snow develops in the morning and increases 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).