A well-defined and potent surface low continues to deliver a significant snowstorm to the mountains and lowlands of the Pacific Northwest. With very cold air in place, we're seeing very high snow ratios. Heavier bands of snow have made it further north than we expected. Northern parts of the Cascades and the Olympics can expect storm totals (Friday night & Saturday) in the 3-8" range. Central Cascades can expect totals in the 5-15" range, while the southern Cascades and Mt. Hood area can expect totals in the 1-3 ft range. Temperatures are bitterly cold in the Cascades and with moderate to strong E winds through the mountain gaps, wind chills are well below zero.
The snowfall should gradually ease from north to south. Precipitation should increasingly focus on the southern Cascades as the low moves onshore near the mouth of the Columbia River early this morning. E winds and snowfall ease throughout the region over the course of the day on Saturday. Flow also becomes increasingly westerly with instability showers seen moving into the coastal areas early this morning.
A subtle shortwave keeps moderate snowfall going Saturday night in the Mt. Hood area with very light snow for much of Washington State.
On Sunday, a slightly stronger shortwave should bring more light to moderate snow across the region. With only a slight moderation in temperatures, expect the high snow ratios to continue.
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
Light to occasionally moderate snow tapering to flurries by afternoon.
Saturday
Night
Snow flurries in the evening, then becoming partly cloudy.
Saturday
Decreasing light to moderate snow tapering to snow flurries late in the day.
Saturday
Night
Cloudy with snow flurries.
Saturday
Moderate snow in the morning becoming light by afternoon.
Saturday
Night
Cloudy with very light snow showers.
Saturday
Decreasing moderate to heavy snow in the morning, becoming light to moderate in the afternoon.
Saturday
Night
Light snow showers.
Saturday
Moderate snow in the morning becoming light by afternoon. Decreasing moderate E winds at the Pass. Moderate to strong ridgeline winds.
Saturday
Night
Cloudy with very light snow showers. Light E winds at the Pass.
Saturday
Moderate to occasionally heavy snow in the morning becoming light by the end of the day. Decreasing moderate to occasionally strong winds at the Pass. Moderate to strong ridgeline winds.
Saturday
Night
Very light snow showers. Light to moderate E winds at the Pass.
Saturday
Light snow.
Saturday
Night
Very light snow or snow flurries.
Saturday
Moderate snow in the morning becoming light by the end of the day.
Saturday
Night
Very light snow showers.
Saturday
Gradually decreasing light to moderate snow.
Saturday
Night
Decreasing light snow showers.
Saturday
Decreasing heavy snow. 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).