A weak shortwave system that passed over the region Monday night ushered in cooler air, increased W winds, and a band of convergence rain/snowfall. Temperatures cooled most significantly over northern and western Washington, with minimal cooling in the southern Cascades and east of the Cascade Crest. A light convergence band produced several inches of snow at Mt. Baker and that band continues to shift south, possibly reaching Stevens or Snoqualmie Pass before fizzling out entirely. Westerly winds continue to accelerate down the east slopes of the Cascades, leading to moderate to strong ridgeline winds in the Wenatchee Mountains. Winds should ease as the shortwave feature moves away. Expect partly to mostly cloudy skies today with more sunshine expected along the east slopes of the Cascades.
Skies continue to clear Tuesday night, with temperatures dropping into the upper 10s and low 20s.
A broad ridge of high pressure centered over the Great Plains amplifies into our region on Wednesday. This should bring warmer temperatures and freezing levels up to 4000-6500 ft after a chilly start to the day. SW flow aloft and E flow through the mountain gaps develop as a deep trough digs southward in the NE Pacific. At the leading edge of the trough, a front will bring precipitation to coastal British Columbia. Expect high and mid-level clouds associated with that front over the Olympics and Mt. Baker areas with thinner clouds and direct sunshine for much of the rest of the Cascades on Wednesday.
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
Partly cloudy.
Tuesday
Night
Partly cloudy.
Tuesday
Light snow tapering off by late morning, then remaining mostly cloudy.
Tuesday
Night
Partly to mostly cloudy skies.
Tuesday
Light snow tapering off by late morning with a weak convergence band focused on the mountain loop area. Remaining mostly cloudy in the afternoon.
Tuesday
Night
Partly to mostly cloudy skies.
Tuesday
Mostly cloudy, becoming partly cloudy late in the day.
Tuesday
Night
Partly cloudy.
Tuesday
A chance of very light snow possible in the morning, then mostly cloudy. Light W wind at the Pass.
Tuesday
Night
Partly cloudy. Light W wind becoming variable at the Pass.
Tuesday
A chance of very light snow possible in the morning, then mostly cloudy. Light W wind at the Pass.
Tuesday
Night
Partly cloudy. Light W wind becoming variable at the Pass.
Tuesday
Mostly cloudy.
Tuesday
Night
Partly to mostly clear.
Tuesday
Mostly cloudy with a slight chance of snow flurries near the Cascade Crest. Decreasing clouds in the afternoon. Moderate to strong winds decreasing throughout the day.
Tuesday
Night
Partly to mostly clear.
Tuesday
Mostly cloudy with clouds decreasing late in the day.
Tuesday
Night
Partly to mostly clear.
Tuesday
Mid-level clouds early, then becoming partly cloudy. Moderate ridgeline winds with strong gusts.
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).