The Pacific Northwest enters a period of NNW flow aloft. Weak disturbances on NW flow bring very light snow showers (a dusting to 2") to the west slopes of the Cascades on Thursday with minimal if any spillover onto the east slopes. Temperatures should remain in the 20s in most mountain locations, keeping snow levels in the 2000-2500 ft range.
A more organized disturbance moves through the area Thursday night and Friday. Light snow picks up first in the central and northern Cascades, then shifts gradually south heading into Friday. Snowfall tapers early Friday from Mt Baker to Stevens Pass, lasting into the morning hours for the southern Washington volcanoes, and into the afternoon for Mt Hood. Weak convergence could also sustain snowfall a bit longer around Snoqualmie Pass. We're currently forecasting 2-6" of snow for the west slopes of the Cascades with a dusting to an inch for areas in the immediate lee of the Cascades. The uncertainty with this system is how much moisture will even make it as far east as the Cascade Crest, with some models indicating most of the moisture gets squeezed out by the Cascade Foothills.
Expect moderate ridgeline winds for exposed terrain from the I-90 corridor southward Thursday night, continuing into the morning hours on Friday for Mt Hood.
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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Thursday
A slight chance of very light snow showers. Mostly cloudy in the morning, becoming cloudy.
Thursday
Night
Increasing light snow.
Thursday
Very light snow showers. Mostly cloudy in the morning, becoming cloudy.
Thursday
Night
Increasing light snow.
Thursday
Very light snow showers. Mostly cloudy in the morning, becoming cloudy.
Thursday
Night
Increasing light snow.
Thursday
Light snow showers (most prevalent at Paradise). Mostly cloudy in the morning, becoming cloudy.
Thursday
Night
Increasing light snow.
Thursday
Very light snow showers. Mostly cloudy in the morning, becoming cloudy. Light ridgeline and W wind at the Pass.
Thursday
Night
Increasing light snow. Light to occasionally moderate ridgeline and light W wind at the Pass.
Thursday
Very light snow showers. Mostly cloudy in the morning, becoming cloudy. Light ridgeline and W wind at the Pass.
Thursday
Night
Increasing light snow. Moderate ridgeline and light W wind at the Pass.
Thursday
Mostly cloudy near the crest with a slight chance of snow flurries. Partly cloudy further east.
Thursday
Night
A chance of very light proximal to the Cascade Crest. Partly cloudy further east.
Thursday
Mostly cloudy near the crest with a slight chance of snow flurries. Partly cloudy further east.
Thursday
Night
A chance of very light proximal to the Cascade Crest. Partly cloudy further east.
Thursday
Mostly cloudy near the crest with a slight chance of snow flurries. Partly cloudy further east.
Thursday
Night
A chance of very light proximal to the Cascade Crest. Partly cloudy further east.
Thursday
Light snow showers focusing on the W slopes of Mt Hood. Mostly cloudy in the morning, becoming cloudy.
Thursday
Night
Increasing light snow focusing on the W slopes of Mt Hood.
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).