An atmospheric river is rolling through the region and laying quite the egg of a forecast on Easter Sunday. Stormy conditions will increase throughout the day over the Olympics and Washington Cascades with the heaviest precipitation rates for the southern slopes of the Olympics and northwest Cascades where several inches of water are expected. Other areas will have heavy precipitation in the afternoon as well and all areas will experience strong S-SW ridgeline winds. Unfortunately, we are on the warm side of the jet stream that's aimed into SW B.C. Snow levels will rise to 5500-6000' in the north and 7000' in the southern Cascades. Mt Hood and areas east of White Pass will be on the southern periphery of the storm and will see less precipitation today.
The moisture tap will begin to ease overnight before another slug of moisture rides up the same frontal boundary on Monday. The cool upper level trough in the Gulf of Alaska that's driving this moisture into our region will begin to approach the coast. This will allow for cooling on the backside of the front. We'll see quite the W-E split in snow levels with 3500-4000' snow levels on the cooler western side of the frontal boundary and 6000-8000' snow levels on the milder eastern edge. Confidence is low in the details regarding this messy weather pattern for Monday.
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
Stormy with moderate to heavy rain and snow, heaviest southern slopes of the Olympics. Strong to extreme ridgeline winds.
Sunday
Night
Light rain and snow showers.
Sunday
Stormy with moderate to heavy rain and snow, heaviest in the afternoon. Strong to extreme ridgeline winds.
Sunday
Night
Light to moderate rain and snow.
Sunday
Stormy with moderate to occasionally heavy rain and snow, heaviest in the afternoon. Strong to extreme ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate to strong ridgeline winds decreasing after midnight.
Sunday
Light to moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Heaviest Paradise and St Helens area. Strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate to strong ridgeline winds.
Sunday
Light to moderate rain and snow becoming moderate in the afternoon. Light east winds at Pass level, moderate SW winds at ridgeline.
Sunday
Night
Light to moderate rain and snow. Light west winds at Pass level, moderate SW winds at ridgeline.
Sunday
Light to moderate rain and snow becoming moderate to occasionally heavy in the afternoon. Light east winds at Pass level, moderate to strong SW winds at ridgeline.
Sunday
Night
Light to moderate rain and snow. Light west winds at Pass level, moderate SW winds at ridgeline.
Sunday
Light to moderate rain and snow becoming moderate in the afternoon.Heaviest precipitation near the Cascade crest. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate winds.
Sunday
Light to moderate rain and snow becoming moderate in the afternoon.Heaviest precipitation near the Cascade crest. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate to strong ridgeline winds.
Sunday
Periods of light rain and snow in the morning becoming light to moderate in the afternoon. Heaviest precipitation near the Cascade crest. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate to strong ridgeline winds.
Sunday
Periods of light rain and snow in the morning becoming light to moderate in the afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow. 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).