The Pacific Northwest enters an increasingly active weather pattern. A weak low-pressure center spins off of Vancouver Island, allowing waves of moisture to continue to drift northward. These waves emanate out the other part of a split system now over the Great Basin. The first wave should bring mostly very light rain and snow as it lifts northward across the central and northern Cascades through the early afternoon hours. The upper-level trough moves onshore with scattered and locally more intense showers for places like Mt Hood and the Olympics. This shower activity reaches the Washington Cascades on Wednesday night. There's a wide range of model forecast precipitation during this time frame with higher resolution models hinting at higher water numbers, so we've gone with a middle-of-the-road solution here.
On Thursday, mostly light (moderate for Mt Hood) stratiform precipitation arrives with an N-S-oriented frontal system. Expect a brief warm-up late in the day that could result in a period of rain at Snoqualmie Pass.
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
Light rain and snow showers. Light ridgeline winds.
Wednesday
Night
Light rain and snow showers. Light to occasionally moderate ridgeline winds.
Wednesday
Light rain and snow at times through the early afternoon, then mostly cloudy. Light ridgeline winds.
Wednesday
Night
Light rain and snow. Light ridgeline winds.
Wednesday
Light rain and snow at times through the early afternoon, then mostly cloudy. Light ridgeline winds.
Wednesday
Night
Light rain and snow. Light ridgeline winds.
Wednesday
Mostly cloudy with scattered rain and snow showers. Light ridgeline winds.
Wednesday
Night
Light rain and snow showers (may be moderate at Paradise). Light ridgeline winds.
Wednesday
Light rain and snow at times through mid-day, then mostly cloudy. Light ridgeline winds and E winds at the Pass.
Wednesday
Night
Light rain and snow showers. Light ridgeline winds. Light E winds switch W at the Pass during the evening hours.
Wednesday
Light rain and snow at times through mid-day, then mostly cloudy. Light ridgeline winds and E winds at the Pass.
Wednesday
Night
Light rain and snow showers. Light ridgeline winds. Light E winds switch W at the Pass during the evening hours.
Wednesday
Light snow at times through the early afternoon hours, then mostly cloudy. Light ridgeline winds.
Wednesday
Night
Scattered snow showers. Light ridgeline winds.
Wednesday
Light snow at times through the mid-day hours, then mostly cloudy. Light ridgeline winds.
Wednesday
Night
Scattered light rain and snow showers. Light to moderate ridgeline winds.
Wednesday
Partly to mostly cloudy early, then a chance of rain or snow showers. Light ridgeline winds.
Wednesday
Night
Scattered light rain and snow showers. Light to moderate ridgeline winds.
Wednesday
Light rain and snow showers. Light ridgeline winds become moderate late in the day.
Wednesday
Night
Light rain and snow showers. 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).