We're in store for a nice day in the mountains with mostly sunny skies and light winds. After a cool start to the day, expect temperatures to warm up with freezing levels rising to 3500-4500 ft. Scattered low-level clouds may build up slightly along the E slopes of the southern Washington Cascades in the afternoon. A broad upper-level trough extending from central Canada will stay over our region through Tuesday night. On Tuesday night, an approaching low and associated frontal system will draw colder air southward along the E slopes of the Cascades and also through the Fraser River Valley overnight. This will bring subfreezing temperatures to most elevations along the E slopes of the Cascades by Wednesday morning.
The aforementioned warm front lifts northward on Wednesday. Light snow develops around Mt Hood in the morning hours as mid and high clouds will fill in the few sunny areas near the Canadian border. By the afternoon, as snowfall becomes moderate intensity for Mt Hood, light snowfall spreads into the southern Washington Cascades, southern Olympics, and areas north of I-90 by the end of the day. Increasing light SE or ESE ridgeline winds become moderate in the afternoon. Don't be surprised to find a few inches of snow even at lower elevations along the E slopes of the Cascades by the end of the day with upslope enhancement. Snow levels should be in the 1000-2000 ft range for the Cascades and around 3000 ft for the Southern Olympics.
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
Mostly sunny.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds.
Tuesday
Night
Mostly clear. Increasing high and mid-level clouds in the early morning hours.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds. Light and variable winds.
Tuesday
Night
Mostly clear. Increasing light ridgeline and E wind at the Pass.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds.
Tuesday
Night
Mostly clear. Increasing light ridgeline and E wind at the Pass.
Tuesday
Mostly sunny.
Tuesday
Night
Mostly clear. Cold.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with a few afternoon clouds.
Tuesday
Night
Mostly clear. Increasing high and mid-level clouds in the early morning hours.
Tuesday
Mostly sunny.
Tuesday
Night
Mostly clear. Increasing high and mid-level clouds after midnight.
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).