A Pacific frontal system will continue to spread light precipitation inland this morning. Precipitation will be light through 10 am and cloud bases will be slow to lower for the Cascades and Mt Hood as the system weakens and stalls offshore. South or Southeast winds ahead of the system have already picked up this morning in some areas, a trend that will continue today. The jet will be aimed into Oregon and south Washington as the front splits, bringing more moderate precipitation to the Mt Hood area in the afternoon.
The front will pass through the Cascades around 10 pm with a switch to westerly winds behind it. The bump in snow levels in the Cascade Passes looks slightly cooler than it did yesterday; snow levels should stay below Pass level throughout the event. A trailing upper level and surface trough will reinvigorate showers through the morning hours as ridgeline westerlies become strong. The heaviest precipitation period should be overnight across the region. Post frontal showers will continue on Friday although additional snowfall totals look fairly run of the mill as winds ease off during the day.
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
Light rain and snow increasing in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and becoming light to occasionally moderate in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and becoming light to occasionally moderate in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and becoming light to occasionally moderate in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and increasing in the afternoon. Increasing ridgeline winds. Light to moderate east winds at Pass level.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and increasing in the afternoon. Increasing ridgeline winds. Moderate east winds at Pass level.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and increasing in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and increasing in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and increasing in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Thursday
Light rain and snow developing this morning and becoming light to moderate in the afternoon. Increasing ridgeline winds.
Thursday
Night
Cloudy with moderate rain and snow showers. Strong ridgeline winds.
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).