A frontal boundary over Oregon spread moderate to occasionally heavy precipitation over the south WA Cascades near and south of Hwy12 and Mt Hood overnight. The cloud cover boundary from this feature is quite stark, with clear skies generally north of Hwy2 and back towards the Olympics. The heaviest of the precipitation is done, but scattered showers, mostly light but occasionally moderate, will continue to pepper the same southern areas this morning. That north/south divide extends to snow levels with cooler temps to the north and milder temperatures to the south. Northern areas that start clear this morning will see some low clouds bubbling up this afternoon along with a chance of light showers mainly for the central and southern WA Cascades and the Mt Hood area.
Tuesday night should be mostly dry, with a few leftover showers along the west slopes of the Cascades and down near Mt Hood. An upper low offshore will pinch off from the main flow and a broad upper level trough and NW flow will take over for the PNW on Wednesday. Light snow showers for the west slopes of the Cascades, occasionally moderate for West Central and West North, will give way to sunnier skies further east of the crest and down near Mt Hood. Look for ridgeline winds to increase on Wednesday as well.
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 in the morning, becoming partly sunny in the afternoon. Light ridgeline winds.
Tuesday
Night
Mostly cloudy with a chance of light snow showers. Light to moderate ridgeline winds.
Tuesday
Mostly sunny in the morning, becoming partly sunny in the afternoon. Light ridgeline winds.
Tuesday
Night
Mostly cloudy with a chance of light snow showers. Light to moderate ridgeline winds.
Tuesday
Mostly sunny in the morning, becoming partly sunny to mostly cloudy in the afternoon with a slight chance of showers. Light ridgeline winds.
Tuesday
Night
Mostly cloudy with a chance of light snow showers. Light to moderate ridgeline winds.
Tuesday
Cloudy with scattered light to occasionally moderate rain and snow showers. Light to moderate ridgeline winds, strongest in the morning.
Tuesday
Night
Mostly cloudy with isolated light snow showers. Light to moderate ridgeline winds.
Tuesday
Cloudy with a chance of light rain and snow showers in the afternoon. Possible sunbreaks late morning through mid-day. Light east winds at Pass level. SE winds at ridgeline in the morning, then SW in the afternoon.
Tuesday
Night
Mostly cloudy with isolated light snow showers. Light to moderate W winds at Pass level and WNW at ridgeline.
Tuesday
Cloudy with scattered light rain and snow showers. Light east winds at Pass level. SE winds at ridgeline in the morning, then SW in the afternoon.
Tuesday
Night
Mostly cloudy with isolated light snow showers. Light to moderate W winds at Pass level and WNW at ridgeline.
Tuesday
Mostly sunny in the morning, becoming partly sunny in the afternoon. Light ridgeline winds.
Tuesday
Night
Partly cloudy. Moderate ridgeline winds.
Tuesday
Mostly sunny north of Hwy 2 in the morning, becoming partly sunny in the afternoon. Cloudy south of Hwy 2 in the morning, becoming mostly cloudy in the afternoon. Light to moderate ridgeline winds.
Tuesday
Night
Partly cloudy. Moderate ridgeline winds.
Tuesday
Cloudy with periods of light rain and snow in the morning, then mostly cloudy in the afternoon. Light to moderate ridgeline winds.
Tuesday
Night
Partly cloudy. Moderate ridgeline winds.
Tuesday
Cloudy with light to moderate rain and snow showers in the morning, then scattered light showers in the afternoon. Moderate ridgeline winds.
Tuesday
Night
Mostly cloudy with scattered light rain and snow showers, especially west-side of the mountain. Moderate 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).