The ridge of high pressure dominating our weather pattern flattens as the ridge axis shifts eastward. Wednesday and Wednesday night remain dry throughout the region. Some high clouds skirt NW Washington and filter into the southern portions of the forecast region on Wednesday. High clouds increase more significantly Wednesday night as a digging trough offshore pushes a disturbance northward toward our region. Freezing levels remain elevated in the 9,500-12,000 ft range. The entrenched cold pool remains in place, but continues to thin. Many ridgelines will become more exposed to SW winds aloft and warming. The thinning of the cold pool will become more pronounced in the afternoon hours, with most ridges moderating above freezing, while valleys and lower-elevation gaps remain cold.
That disturbance starts to bring light precipitation into our region from the south on Thursday. Precipitation is likely to reach the Mt Hood region in the morning and the southern half of the Washington Cascades in the afternoon. Precipitation type remains tricky as pockets of cold air remain at lower elevations and in the mountain gaps, so expect a mix of snow, rain, and freezing rain with high snow levels ranging from 3000 ft up to ridgeline elevations, depending on how much cold, dry air remains in a given location as that moisture moves in.
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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Wednesday
Mostly sunny with periods of high cloud cover. Warm.
Wednesday
Night
Mostly clear with occasional thin, high clouds. Warm.
Wednesday
Mostly sunny with periods of high cloud cover. Warm.
Wednesday
Night
Mostly clear with occasional thin, high clouds. Warm.
Wednesday
Mostly sunny with periods of filtered sunshine. Warm.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken in the early morning hours.Mild.
Wednesday
Mostly sunny. Warm.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken in the early morning hours.Mild.
Wednesday
Mostly sunny with periods of thin high clouds. Warm above 5000 ft, cold below. Light ridgeline and E wind at the Pass.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken in the early morning hours. Warm above 5000 ft, cool below. Light ridgeline and decreasing mostly light E wind at the Pass.
Wednesday
Mostly sunny with periods of thin high clouds. Warm above 5000 ft, cold below. Light ridgeline and light to moderate E wind at the Pass.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken in the early morning hours. Warm above 5000 ft, cool below. Light ridgeline and decreasing mostly light E wind at the Pass.
Wednesday
Mostly sunny with periods of thin high clouds. Warm above 5000 ft, cold below.
Wednesday
Night
Mostly clear in the evening, then high clouds increase overnight. Warm above 5000 ft, cool below.
Wednesday
Mostly sunny with periods of thin high clouds. Warm above 5000 ft, cold below.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken in the early morning hours. Warm above 5000 ft, cool below.
Wednesday
Mostly sunny with periods of thin high clouds. Warm above 5000 ft, cold but moderating below.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken overnight. Warm above 5000 ft, cool below.
Wednesday
Mostly sunny with periods of obscured skies. Warm above 5000 ft, cooler below.
Wednesday
Night
Mostly clear in the evening, then high clouds lower and thicken overnight. Warm above 5000 ft, cool below.
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).