The persistent convergence zone and snow showers that lingered overnight between the central Cascade Passes should wind down this morning. Hood continues to receive moderate snowfall with moderate to strong winds today. With that exception, most areas will enjoy a relative lull before the snowfall ramps up again later. Once it does, we're in for a prolonged and impactful storm associated with an atmospheric river that'll last through Thursday at some point.
The nose of the leading warm front pushes into the area by mid day, spreading light but increasingly moderate snow showers to the west slopes and passes. On the east side of the crest we'll see increasing clouds with light snow starting up before the end of the day. Temperatures begin a gradual nudge upwards but remain cool today.
Snowfall rates will steadily increase this evening, becoming heavier with strengthening SW ridgeline winds. The firehose slowly tilts to the SSW during the day on Wednesday as heavy precipitation and strong to extreme winds continue. Snow levels rise overnight and hang out in the 4,000-4,500ft range for much of the day on Wednesday. Light east flow through the passes may slow the warming process, but it'll eventually be overtaken by the warm air mixing in. The heaviest precipitation during the day is aimed at the north Cascades as the front stalls out a bit.
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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Tuesday
Partly cloudy, becoming cloudy with light snow showers.
Tuesday
Night
Stormy, with moderate to heavy snowfall.
Tuesday
Becoming mostly cloudy with light snow showers by mid day. Increasing SW ridgeline winds.
Tuesday
Night
Moderate to heavy snow with strong SW ridgeline winds.
Tuesday
Becoming mostly cloudy with light snow showers by mid day. Increasing SW ridgeline winds.
Tuesday
Night
Moderate to heavy snow with strong SW ridgeline winds.
Tuesday
Mostly cloudy and breezy with light snow showers starting by mid day.
Tuesday
Night
Moderate to heavy snow with strong SW ridgeline winds.
Tuesday
Light snow showers tapering in the morning. Mostly cloudy with light snowfall starting up again by mid afternoon. Snowfall becomes picks up and becomes moderate by sunset.
Tuesday
Night
Moderate to heavy snowfall and increasing SW ridgeline winds.
Tuesday
Mostly cloudy with a stray snow shower this morning, then light snowfall starting up again by mid afternoon. Snowfall becomes picks up and becomes moderate by sunset.
Tuesday
Night
Moderate to heavy snowfall and increasing SW ridgeline winds.
Tuesday
Partly sunny with broken skies, becoming mostly cloudy later with light snowfall to end the day.
Tuesday
Night
Moderate snowfall and stormy with increasing ridgeline winds.
Tuesday
Partly sunny with broken skies, becoming mostly cloudy later with light snowfall. Ridgeline winds increasing later.
Tuesday
Night
Moderate to heavy snowfall and stormy with increasingly strong ridgeline winds.
Tuesday
Partly cloudy and breezy, becoming mostly cloudy later with light snowfall. Ridgeline winds increasing later.
Tuesday
Night
Moderate to heavy snowfall and stormy with increasingly strong ridgeline winds.
Tuesday
Moderate snowfall with strong ridgeline winds. Snowfall becomes lighter mid morning, then picks up to moderate again by mid day.
Tuesday
Night
Stormy, with moderate to heavy snow and 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).