While the calendar has turned to March and the first day of meteorological spring, the weather pattern has firmly decided it's still winter. An upper-level trough over the region will be the dominant weather feature over the next few days. While the storm track pummels California with heavy precipitation, we'll see showers and low snow levels.
Today, showers will be focused on the Olympic peninsula and more scattered over the Cascades this morning. An upper level disturbance will enhance shower activity this afternoon through this evening and turn the flow aloft more southerly. While the precipitation amounts are not impressive by PNW standards, low density snow will easily squeeze out a few inches with prolonged showers. The air mass is unstable, so you may see graupel mix in during the afternoon and heavier showers. Snow levels will rise to around 1500-2000' each day and with freezing levels 500-1000' higher and fall to near sea-level overnight. Temperatures will fall rapidly with height, so if you're planning to push into upper elevations, be prepared for temperatures in the teens. We'll see periods of moderate to locally strong ridgeline winds.
We'll see a compact low pressure system bring more showers and bring a ramp up in wind Friday night, followed by a switch to WSW winds on Saturday. There's low confidence in the timing of individual weather features in this pattern.
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
Cloudy with light to moderate snow showers. Heaviest showers southwest slopes of the Olymipcs. Moderate ridgeline winds.
Friday
Night
Cloudy with light to moderate snow showers. Heaviest showers southwest slopes of the Olymipcs. Periods of moderate ridgeline winds.
Friday
Mostly cloudy with light snow showers this morning, then becoming light to moderate showers in the afternoon. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Periods of moderate ridgeline winds.
Friday
Mostly cloudy with light snow showers this morning, then becoming light to occasionally moderate showers in the afternoon. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Periods of moderate ridgeline winds.
Friday
Mostly cloudy with light to occasionally moderate showers. Moderate to strong ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Moderate to strong ridgeline winds.
Friday
Mostly cloudy with light to occasionally moderate scattered snow showers. Periods of moderate Pass level and ridgeline S-SE winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Moderate SE Pass level and ridgeline winds.
Friday
Mostly cloudy with light to occasionally moderate scattered snow showers. Periods of moderate Pass level and ridgeline S-SE winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Moderate SE Pass level and ridgeline winds.
Friday
Mostly cloudy with light scattered snow showers becoming light to occasionally moderate in the afternoon. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with scattered light snow showers. Periods of moderate ridgeline winds.
Friday
Mostly cloudy with light scattered snow showers becoming light to occasionally moderate midday. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Moderate ridgeline winds.
Friday
Mostly cloudy with light scattered snow showers becoming light to occasionally moderate midday. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. Moderate ridgeline winds.
Friday
Mostly cloudy with light to occasionally moderate snow showers. Strong ridgeline winds.
Friday
Night
Mostly cloudy with scattered light to occasionally moderate snow showers. 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).