A compact band of rain and snow is arriving in the mountains this morning along with a well-defined cold front. Precipitation will be heaviest just before and as the front passes overhead. For most locations, this appears to be between 10 and 1. This includes areas east of the Cascade Crest. While the Passes may start the storm as rain or a rain-snow mix, once the front arrives, colder air will pour into the region. Freezing levels will quickly drop as we head into the afternoon. Post frontal showers and a Puget Sound Convergence Zone will maintain precipitation along the west slopes of the Cascades and Passes. However, the upper air mass dries quickly following the front. So, don't be surprised if you see a few sun breaks in the afternoon. As temperatures drop and sun breaks start to form, WNW winds increase. Strong and gusty winds will likely impact locations along the east side of the Cascades and Mt Hood this afternoon and evening.
Overnight, snow showers continue for the west slopes and Passes. Precipitation may be locally heavier as the Puget Sound Convergence Zone stays aimed at the central Cascades between Hwy 2 and I90. Low-level moisture and cooing temperatures could result in plenty of low clouds and even fog for the east side valleys.
Sunday will be a bit of a transition day before our next weather system. A few showers may hang on into Sunday morning, but most locations should find cold and generally dry conditions to start the day. Clouds will increase ahead of a weak warm front. By the afternoon, temperatures should slowly start to rise, but the bulk of the precipitation seems to hold off until overnight.
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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Saturday
Cloudy and snow showers this morning. Sun breaks and clearing in the afternoon. Light W winds becoming moderate.
Saturday
Night
Partly to mostly cloudy with the chance of isolated snow showers. Light to moderate W winds decreasing.
Saturday
Cloudy with snow, heavy at times in the morning. Becoming showery. Sun breaks possible in the afternoon. Light to moderate SW winds.
Saturday
Night
Mostly cloudy with isolated snow showers. Moderate W winds becoming light.
Saturday
Cloudy with rain and snow, heavy at times in the morning. Showers with a few sun breaks in the afternoon. Light to moderate winds becoming WNW. A Puget Sound Convergence Zone will bring localized heavier precipitation near Hwy 2 and I-90.
Saturday
Night
Cloudy with snow showers. A Puget Sound Convergence Zone will bring locally heavier precipitation near I-90. Moderate WNW winds decreasing overnight.
Saturday
Cloudy with rain and snow in the morning. Heaviest near the volcanoes. Sun breaks and clearing with showers possible in the afternoon, especially near the crest. Winds increasing and becoming moderate WNW.
Saturday
Night
Partly to mostly cloudy with snow showers. Moderate WNW winds decreasing.
Saturday
Cloudy with rain and snow heaviest in the morning. Showers with a few sun breaks in the afternoon. Winds becoming westerly and increasing during the day. A Puget Sound Convergence Zone could bring periods of locally heavier precipitation in the afternoon.
Saturday
Night
Cloudy with snow showers. A Puget Sound Convergence Zone could bring periods of locally heavier precipitation. Light to moderate westerly winds.
Saturday
Cloudy with rain and snow heaviest in the morning. Snow showers in the afternoon with a few sun breaks possible. Moderate westerly winds increasing in the afternoon.
Saturday
Night
Cloudy with snow showers. A Puget Sound Convergence Zone could bring locally heavier precipitation. Moderate W winds.
Saturday
Cloudy with showers in the morning. Heaviest near the crest. Sun breaks and clearing in the afternoon. Winds becoming westerly and moderate.
Saturday
Night
Partly to mostly cloudy with isolated showers possible. Moderate to strong W winds decreasing slightly.
Saturday
Cloudy with showers in the morning. Sun breaks and clearing with isolated showers in the afternoon. Strong and gusty W winds developing during the day.
Saturday
Night
Partly to mostly cloudy with a few showers near the crest. Strong and gusty WNW winds decreasing slightly overnight.
Saturday
Cloudy with showers in the morning. Sun breaks and clearing with isolated showers in the afternoon. Strong and gusty WNW winds developing during the day.
Saturday
Night
Partly to mostly cloudy with a few isolated showers possible. Moderate to strong WNW winds.
Saturday
Cloudy with rain and snow in the morning. Could be heavy at times. Becoming showers in the afternoon with a few sun breaks possible. Strong and gusty W winds developing during the day.
Saturday
Night
Cloudy with snow showers. Strong and gusty W 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).