With a cold upper trough remaining in place and an upper low parked just offshore, Sunday will be quite similar to Saturday. Light to occasionally moderate snow showers focus on the west slopes of the Cascades and southern Olympics, with increasing spillover to the lee side of the ranges during the afternoon as convection builds up. Convective showers come with graupel and, in isolated cases, some small hail. Snow showers will be heaviest in the southern Washington Cascades, with Mt Rainier and Mt St Helens both likely to pick up 6-12" of snow by the end of the day. Mt Baker, the central Cascades Passes, and Mt Hood can expect 2-6" of snow. Winds have decreased significantly and are mostly light across Washington State. However, as a disturbance rotates through southern Washington State, a more westerly component has increased moderate wind speeds and strong gusts early this morning for the east slopes of Mt Hood.
Snow showers decrease during the evening hours, but another weak disturbance passing through the southern Cascades in the early morning hours on Monday could bring a period of moderate snowfall from around Snoqualmie Pass to Mt Hood. Scattered light to occasionally moderate snow showers continue on Monday.
Snow levels remain vacillating between sea level and 1500 ft with diurnal fluctuations. Afternoon freezing levels rise to 1500-3000 ft in areas not receiving snowfall.
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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Sunday
Mostly cloudy with scattered light snow showers (moderate at times in the southern part).
Sunday
Night
Mostly cloudy with scattered light snow showers.
Sunday
Mostly cloudy with scattered light to occasionally moderate snow showers.
Sunday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers.
Sunday
Mostly cloudy with scattered light to occasionally moderate snow showers.
Sunday
Night
Mostly cloudy with scattered light snow showers.
Sunday
Mostly cloudy with scattered light to moderate snow showers (heaviest for Mt St Helens and Paradise).
Sunday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers.
Sunday
Mostly cloudy with scattered light snow showers. Light ridgeline and E wind at the Pass switches W by late morning.
Sunday
Night
Mostly cloudy with scattered light snow showers. Light ridgeline and W wind at the Pass.
Sunday
Mostly cloudy with scattered light to occasionally moderate snow showers. Light ridgeline and E wind at the Pass switches W by late morning.
Sunday
Night
Mostly cloudy with scattered light snow showers. Light to occasionally moderate ridgeline and light W wind at the Pass.
Sunday
Partly cloudy in the morning, then mostly cloudy with scattered light snow showers in the afternoon.
Sunday
Night
Mostly cloudy with scattered light snow showers tapering overnight.
Sunday
Partly cloudy in the morning, then mostly cloudy with scattered light snow showers mainly in the afternoon.
Sunday
Night
Mostly cloudy with scattered light snow showers tapering overnight.
Sunday
Partly cloudy in the morning, then mostly cloudy with a few light snow showers in the afternoon.
Sunday
Night
Partly cloudy with a few light snow showers, mainly during the evening hours.
Sunday
Mostly cloudy with scattered light to occasionally moderate snow showers increasing from mid-morning onwards. Moderate ridgeline winds.
Sunday
Night
Mostly cloudy with scattered light snow showers. A chance of moderate snow overnight. Moderate to occasionally 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).