745 AM: Updated cloud forecast for Snoqualmie Pass and West South for more sunbreaks today
We're in for more of the same today, mostly, with just some subtle changes. A strong polar jet over British Columbia continues to spill over high W-NW wind south of the border with strong to locally extreme ridgeline winds over parts of the Cascades, and especially at higher elevations. A weak upper level disturbance this afternoon will kick up winds another notch, especially along the eastern slopes of the Cascades. This has been an impressive multi-day wind event, not associated with a strong low-pressure system, but with a broad upper-level trough over much of the continent.
Locally moderate snow showers in the Mt Baker area should become more scattered this afternoon, as well as along the western parts of the West Central zone. The low clouds will continue thin today, and we can expect more sunshine mixing in for the west slopes near and south of I-90 than the prior 2 days. We'll see more warming today for the all areas, but the warmest temperatures/freezing levels will be felt over the south WA Cascades and Mt Hood area.
The winds finally back off late Friday night into Saturday morning, and the low clouds will relent as well as skies clear for areas along the west slopes of the Cascades during the day. However, high clouds from a cut-off upper low off the CA coast will spill northwards towards the Columbia River Gorge, with filtered sunshine at times. We'll see freezing levels rise everywhere and well above most trailheads and ski area bases.
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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Friday
Mostly cloudy with scattered light to occasionally moderate snow showers, except partly sunny north and eastern slopes. Moderate to strong ridgeline winds.
Friday
Night
Partly cloudy with a chance of light rain or snow showers western part of the range. Moderate to strong ridgeline winds easing after midnight.
Friday
Cloudy with light to occasionally moderate rain and snow showers in the morning, heaviest western part of the zone. Showers becoming more scattered in the afternoon. Strong ridgeline winds.
Friday
Night
Cloudy with a chance of light rain or snow showers in the evening. Strong ridgeline winds becoming moderate after midnight.
Friday
Cloudy with light to occasionally moderate rain and snow showers in the morning, heaviest western part of the zone. Showers becoming more scattered in the afternoon. Strong ridgeline winds.
Friday
Night
Cloudy with a chance of light rain or snow showers in the evening. Strong ridgeline winds becoming moderate after midnight.
Friday
Mostly cloudy with a chance of light showers western part of the zone. Partly to mostly sunny eastern and southern part of the zone. Mostly clear high on the volcanoes. Strong ridgeline winds.
Friday
Night
Partly clear. Strong ridgeline winds becoming moderate after midnight.
Friday
Cloudy with occasional light snow showers. Strong W ridgeline winds, moderate W at Pass level.
Friday
Night
Cloudy with a chance of light rain or snow showers in the evening. Strong W ridgeline winds, moderate W at Pass level in the evening, winds becoming moderate after midnight.
Friday
Mostly cloudy with sunbreaks and scattered light snow showers. Strong W ridgeline winds, moderate W at Pass level.
Friday
Night
Mostly cloudy with a chance of light rain or snow showers in the evening. Strong W ridgeline winds, moderate W at Pass level in the evening, winds becoming moderate after midnight.
Friday
Cloudy with occasional light snow showers near the Cascade crest, mostly cloudy further east. Strong to extreme ridgeline winds.
Friday
Night
Cloudy with occasional light snow showers near the Cascade crest in the evening, then mostly cloudy. Partly to mostly clear further east. Strong to occasionally extreme ridgeline winds becoming moderate after midnight.
Friday
Mostly cloudy with occasional light snow showers near the Cascade crest, partly sunny further east. Strong to extreme ridgeline winds.
Friday
Night
Mostly cloudy with a chance of a light snow shower near the Cascade crest in the evening, then mostly cloudy. Partly to mostly clear further east. Strong to extreme ridgeline winds becoming moderate to strong after midnight.
Friday
Partly to mostly cloudy near the Cascade crest, partly to mostly clear further east. Strong to extreme ridgeline winds.
Friday
Night
Partly to mostly cloudy near the Cascade crest in the evening, then mostly clear. Mostly clear further east all night. Strong to extreme ridgeline winds becoming moderate to strong after midnight.
Friday
Mostly sunny with a few high clouds. Moderate to occasionally strong ridgeline winds, stronger at higher elevations.
Friday
Night
Mostly clear with a few high clouds. Moderate to occasionally strong ridgeline winds in the evening, becoming light to moderate after midnight.
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).