Tuesday will be a classic pre-frontal day with increasing cloud cover. Some areas might enjoy a few hours of filtered sunshine before the clouds thicken later in the day. Temperatures will continue to moderate above the inversion, and will be most noticeable on the west side of the crest. On the east side, very cold arctic air has settled into place. Easterly winds are still blowing that icy breeze through mountain passes, but they should relent a little compared to the past few days. Snowfall may begin first in the southwest and Hood before sunset, but should hold off until evening for the rest of our region.
A front swings in from the southwest and lifts north across the Cascades Tuesday night. This first act should give most mountain areas a nice fresh blanket of 6-12" through Wednesday morning. Behind the front, a low pressure moves into the corner pocket of the Olympic/ Vancouver Island area and slows down. This sets the stage for more disturbances to ripple through in strong westerly flow, which is expected to bring significant snowfall (another 1-2ft+) to the mountains. The front and following disturbances could be likened to a breakdancer throwing a some moves as they slide into the center, then really get down for a while before moving on. By 4pm on Wednesday many areas should have well over a foot of new snow, and it'll be stacking up quickly. Snow densities are expected to be slightly higher than what we've enjoyed recently, but with snow levels in the 0-2,000ft range, we're still talking about cold snow.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later.
Tuesday
Night
Light snowfall.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds and ridgetop winds into the moderate range later.
Tuesday
Night
Light to moderate snowfall. Snow becoming heavy by early morning.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later.
Tuesday
Night
Light to moderate snowfall.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds and light snowfall later.
Tuesday
Night
Light to moderate snowfall. Increasing ridgetop winds.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later. Light to moderate east winds at pass level.
Tuesday
Night
Light to moderate snowfall.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later with a chance of very light snow towards the end of the day. Moderate east winds at pass and ridgetop.
Tuesday
Night
Moderate snowfall. Light to moderate east winds at pass and ridgetop.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later.
Tuesday
Night
Light snow and cold.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later.
Tuesday
Night
Light to moderate snow and cold.
Tuesday
Mostly cloudy with a chance of filtered sunshine. Increasing clouds later.
Tuesday
Night
Light to moderate snow.
Tuesday
Thickening clouds and increasing ridgetop winds. Light snowfall starting by mid afternoon.
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).