We hope you benefit from significant updates to the mountain weather forecast, launched with this forecast issuance.
A wedge-shaped trough elongates as it moves into the region Thursday night with an associated modest cold front moving across the region during the evening hours. This should bring bands of light snow or snow showers through the region. As the trough moves in over Washington State, the stronger pressure gradient remains over Oregon, bringing moderate winds and more snowfall to Mt. Hood. The trough settles further into the region on Friday, focusing the light snowfall increasingly on the southern Washington and Mt. Hood regions of the Cascades as snow showers wind down in northern Washington State. Friday night, the trough moves eastward, the flow aloft switches more northerly, and precipitation should end in the southern parts of the forecast region. Expect around 1 ft of snow for Mt. Hood and 6-10" for Paradise with lesser amounts elsewhere through Friday night.
On Saturday, a quick-moving ridge of high pressure moves over the region, giving us a partly to mostly sunny and cool day. Offshore winds will strengthen as a stronger system approaches from the west.
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
Night
Periods of light snow. Gradual cooling. Light to occasionally moderate winds.
The next front, attached to a deep Aleutian Low, should bring plenty of moisture as it arrives late Saturday night or Sunday morning. The system should bring plenty of post-frontal snow shower activity under a broad trough through Monday. Expect a snow event primarily for the region with upwards of 1 ft of snow for much for the west slopes of the Cascades by the end of the day Monday. Moderate E flow at the outset of the storm Saturday night should gradually relent and switch back westerly as the trough axis shifts E Sunday night. The E flow should keep pass-level temperatures low throughout the storm as cold air also works in aloft. In some parts of our forecast area, snow showers may not shut off entirely on Monday as a weak ridge transits the area.
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).