The Pacific Northwest is in the midst of a very wet and active weather pattern. A warm front is lifting across Washington State on Friday, bringing a broad band of steady light to moderate snow, that may be heavy at times in the Mt. Baker area. SW winds should continue to ramp up in the moderate range at ridgelines across the region on Friday. As the warm front lifts northward, areas from highway 90 southward may see some slightly drier weather during the middle of the day. The associated cold frontal precipitation reaches the Olympics in the late afternoon, then spreads moderate to heavy rain and snow at rising snow levels throughout the Cascades during the evening hours. Most of this precpitation should come as rain right at Snoqualmie pass level, but areas above 4000 ft should see significant accumulations. Rain and snowfall taper to showers and convergence zone activity overnight Friday as snow levels in Washington State cool back to Snoqualmie Pass level. Models indicate the convergence setting up between Snoqualmie Pass and the Mountain Loop.
Saturday features a break between storms with increasing westerly flow continuing to bring in moisture to maintain light rain and snow shower activity with 3000-4000 ft snow levels. Late in the day, the beginning of an atmospheric river event spreads increasing moderate precipitation to the region in the afternoon, which may become heavy in the Olympics by the end of 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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Friday
Periods of light rain and snow in the morning, becoming moderate to heavy late in the day. Warming. Increasing moderate to strong ridgeline winds.
Friday
Night
Moderate rain and snow in the early evening rapidly tapering to light rain and snow showers. Cooling. Decreasing moderate winds.
Friday
Increasing rain and snow developing in the morning and becoming moderate to heavy by late morning. Gradually rising snow levels. Increasing moderate to strong ridgeline winds.
Friday
Night
Heavy rain and snow in the evening tapering to light rain and snow showers from midnight onwards. Cooling after midnight. Decreasing moderate winds.
Friday
Light to moderate rain and snow, peaking mid-morning. Warming trend. Increasing moderate ridgeline winds.
Friday
Night
Heavy rain and snow in the evening tapering to light to moderate rain/snow showers and convergence activity. Cooling in the late evening. Decreasing moderate to strong ridgeline winds.
Friday
Light rain and snow peaking in the mid-morning hours. Gradual warming. Increasing moderate winds.
Friday
Night
Heavy rain and snow in the evening (moderate at Crystal), tapering to light rain and snow showers after midnight. Gradual cooling. Decreasing moderate ridgeline winds.
Friday
Light rain and snow, peaking mid-morning. Warming trend. Increasing moderate ridgeline winds. Light and variable wind at pass level.
Friday
Night
Heavy rain and snow in the evening tapering to light to moderate rain/snow showers and convergence activity. Cooling in the late evening. Decreasing moderate to strong ridgeline winds.
Friday
Light rain and snow, peaking mid-morning. Warming trend. Increasing moderate ridgeline winds. Light and variable wind at pass level.
Friday
Night
Heavy rain and snow in the evening tapering to light to moderate rain/snow showers and convergence activity. Cooling in the late evening. Decreasing moderate to strong ridgeline winds.
Friday
Light snow peaking in the mid-day hours. Gradual warming. Increasing moderate ridgeline winds.
Friday
Night
Moderate to occasionally heavy rain and snow in the evening. Cooling from late evening onwards. Moderate winds becoming strong.
Friday
Light rain and snow peaking in the mid-day hours. Gradual warming. Increasing moderate ridgeline winds.
Friday
Night
Moderate to heavy rain and snow in the evening. Cooling from late evening onwards. Strong winds.
Friday
Mostly cloudy with a slight chance of very light snow. Increasing light to moderate winds.
Friday
Night
Moderate rain and snow in the evening, then light rain and snow showers tapering after midnight. Moderate winds gusting strong.
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).