An upper trough continues to move toward our region. A surface low at the leading edge of the trough moved onshore over British Columbia early this morning, enhancing rain and high elevation snow shower activity, particularly over NW Washington. A more continuous band of moderate rain/snow across northern Oregon and the Columbia Gorge area has formed Tuesday night. We expect precipitation across the region to gradually ease, but expect light shower activity to fill in during the afternoon and evening hours across the central and southern Washington Cascades as well. Temperatures begin to cool and bring snow back to mid-mountain locations overnight.
The upper trough moves onshore on Thursday, reducing the moisture feed and further cooling temperatures. Winds should be light throughout the forecast period. By Thursday, rain and snow showers may be very snow moving. Both Wednesday and Thursday expect the potential for afternoon graupel showers that could be locally intense and may be slow-moving on Thursday.
Upper elevations of Mt. Baker could pick up 5-10" of snow over the next 36 hours with 3-6" possible for Mt. Hood above 5500 ft and less than 3" likely for Hurricane Ridge.
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
Light rain and snow showers.
Wednesday
Night
Very light rain and snow showers with cooling temperatures.
Wednesday
Moderate rain and snow showers.
Wednesday
Night
Light rain and snow showers.
Wednesday
Light rain and snow showers.
Wednesday
Night
Light rain and snow showers.
Wednesday
Light rain and snow showers.
Wednesday
Night
Light rain and snow showers.
Wednesday
Light rain and snow showers. Light E wind at the Pass becoming variable.
Wednesday
Night
Light rain and snow showers. Variable wind becoming light W at the Pass.
Wednesday
Light rain and snow showers. Light E wind at the Pass becoming variable.
Wednesday
Night
Light rain and snow showers. Variable wind becoming light W at the Pass.
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).