We have an atypical weather pattern for the next few days with strong upper level high pressure flopping into British Columbia and a closed low digging over eastern OR/WA today and eventually shifting to the Great Basin on Wednesday. A tight gradient between these two broad scale features will keep moderate to strong E-NE ridgeline winds over much of the forecast region. Winds will typically be the strongest overnight when they aren't battling the diurnal influences of a strong mid-April sun. Exposed ridgelines in the West South, East Central, East South and Mt Hood will see the strongest winds from this event.
Freezing levels will be on the rise over the next two days bumping up 500'-1000' every 24 hours. As the upper level ridge and associated warm air mass become the dominant weather feature toward midweek, expect freezing levels to stay elevated overnight. Areas further north like the Olympics and Mt Baker area will warm a bit faster on Wednesday while areas further south, like Mt Hood, closer to the closed low will see muted warming and prolonged wind.
We should see few to scattered cumulus build up around 7000-9000' in the afternoon along the east slopes of the Cascades, near the Cascade crest and for Mt Hood this afternoon with full sun for areas further west.
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. Moderate ridgeline winds.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny. A few afternoon clouds. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny. Strong ridgeline winds.
Tuesday
Night
Mostly clear. Strong ridgeline winds.
Tuesday
Mostly sunny. A few afternoon clouds. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly clear. Moderate ridgeline winds.
Tuesday
Mostly sunny. A few afternoon clouds. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly clear. Moderate to strong ridgeline winds.
Tuesday
Mostly sunny. A few afternoon clouds. Moderate to strong ridgeline winds.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny. A few afternoon clouds. Strong ridgeline winds.
Tuesday
Night
Mostly clear. Strong ridgeline winds.
Tuesday
Mostly sunny. A few afternoon clouds. Strong ridgeline winds.
Tuesday
Night
Mostly clear. Strong ridgeline winds.
Tuesday
Mostly sunny. A few afternoon clouds. Strong to extreme 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).