A dynamic storm system is underway this morning, with heavy precipitation and strong to extreme winds expected in many areas, as well as a slow cooling trend over the next 24 hours. A deep low pressure system will drift over the northern inland waters this afternoon, and then weaken as it passes east of the Cascades tonight. Heavier precipitation this morning rotating out from the low will favor the volcanoes, Crystal mountain area, and the Olympic peninsula. Cool east flow through the Passes has kept Stevens Pass as snow while patchy freezing rain is possible at Snoqualmie Pass. Along the east slopes of the Cascades, rain transitions to freezing rain or snow along the Hwy 2 corridor, and then it's been lightly snowing at Mazama. These areas will gradually warm today, with a switch to west winds in the afternoon helping to mix down some warmer air.
To the south of the low, strong to extreme winds will pummel the Mt Hood region today and tonight along with a cooling trend and heavy precipitation, which should create white-out conditions. Strong S winds can also be found in the Crystal area today. An upper level feature will swing through in the afternoon, and usher in a period of strong to extreme W winds as far north as Stevens Pass and the Highway 2 corridor Tuesday evening and overnight. Heavy showers will shift from the Mt Hood/south Washington Cascades up to the west-central/Mt Baker area Tuesday night. This will be snow accumulation at trailheads and Pass levels as snow levels fall to 3000' overnight.
Showers and winds will wind down on Wednesday as snow levels settle around 2500'.
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
Stormy with moderate to heavy rain and snow. Strong winds easing in the afternoon.
Tuesday
Night
Moderate rain and snow showers. Moderate to strong winds.
Tuesday
Stormy with moderate to heavy rain and snow. Strong winds easing in the afternoon.
Tuesday
Night
Moderate to occasionally heavy rain and snow showers. Moderate to strong winds.
Tuesday
Moderate to heavy rain and snow. Moderate to strong winds easing in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers. Strong winds.
Tuesday
Stormy with moderate to heavy rain and snow. Strong to extreme winds.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers tapering off after midnight. Strong to extreme winds.
Tuesday
Periods of light to moderate rain and snow, increasing in the afternoon. Light east winds at Pass level becoming West in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers. Strong W winds.
Tuesday
Periods of light to moderate rain and snow, increasing in the afternoon. Chance of freezing rain near and east of the Pass this morning. Light east winds at Pass level becoming West in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers tapering off after midnight. Strong to extreme W winds.
Tuesday
Light to moderate rain and snow.
Tuesday
Night
Light to occasionally moderate rain and snow showers. Winds becoming moderate to strong.
Tuesday
Light to moderate rain and snow. Patchy freezing rain in the valleys through mid-day.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers tapering off after midnight. Strong to extreme winds.
Tuesday
Light to moderate rain and snow. Winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers tapering off after midnight. Extreme winds.
Tuesday
Stormy with moderate to heavy rain and snow. Extreme winds.
Tuesday
Night
Stormy with moderate to heavy rain and snow showers tapering off after midnight. Extreme 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).