The next frontal system is making its way into Western Washington this morning. Precipitation is becoming widespread along the coast and the Olympics and is beginning to push into the west slopes of the Cascades, with snow levels around 4000ft. The cold front will pass through this afternoon, bringing heavier precipitation and strong SW winds. Snow levels will bump up just a bit over the course of the day. Though both sides of the range will see the action, the western slopes and especially the volcanoes are favored to see the largest totals. A convergence zone takes aim at the West North and West Central zones this evening, bringing continued precipitation, while showers and wind speeds begin to taper elsewhere as an upper-level ridge starts to build overnight into Wednesday.
As the ridge takes form, any remaining showery activity should come to a halt on Wednesday morning, perhaps with the exception of a stray drop or two near the Canadian border. It’s a relatively weak ridge, so we won’t likely go full bluebird. Expect a mix of sun and clouds with increasing temperatures. Calm weather lasts through the day and into Thursday in advance of the next system.
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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Tuesday
Moderate to occasionally heavy showers in the morning, becoming lighter in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with a chance of showers and partial clearing late. Ridgeline winds decrease to moderate overnight.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with moderate to occasionally heavy showers, decreasing overnight. Moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with moderate to occasionally heavy showers, decreasing overnight. Moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Strong ridgeline winds.
Tuesday
Night
Mostly cloudy with snow showers, heaviest on the volcanoes. Strong ridgeline winds decrease to moderate overnight.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Moderate to strong SE then SW ridgeline winds. Light E winds at Pass level becoming moderate W in the afternoon.
Tuesday
Night
Mostly cloudy with scattered showers and moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Moderate to strong SE then SW ridgeline winds. Light E winds at Pass level becoming moderate W in the afternoon.
Tuesday
Night
Mostly cloudy with scattered showers and moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then light to moderate showers in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with scattered showers and moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then light to moderate showers in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with scattered showers near the crest, and partial clearing further east. Strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then light to moderate showers in the afternoon. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly cloudy with scattered snow showers, decreasing overnight. Partial clearing late. Moderate to strong ridgeline winds.
Tuesday
Mostly cloudy with scattered light to moderate rain and snow showers in the morning, then moderate to occasionally heavy showers in the afternoon. Strong ridgeline winds.
Tuesday
Night
Mostly cloudy with scattered snow showers, decreasing overnight. Partial clearing late. Moderate to 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).