Low-level clouds are spread across much of the forecast region this morning with a few stray showers bringing drizzle to the west slopes of the Central Cascades. As the day moves on, these clouds should thin out and allow periods of significant sunshine for many of our mountain areas particularly east of the crest and south of I-90. NW flow and lingering moisture will likely keep places near the Mt Loop Highway and Snoqualmie Pass cloudier at low elevations and could produce a few very isolated showers. We're situated squarely between a high-pressure ridge in the western Pacific and a deep trough over the Rockies. With the jet stream directly overhead, you may see bands of passing high and mid level clouds, especially in the afternoon.
This high-pressure ridge and overhead jet will be the dominant features in our weather this week. Overnight, a small disturbance slides along the jet stream and into Washington. While this isn't a real storm, it should provide just enough lift to create isolated showers near and west of the crest and spread clouds a bit further east. Along with the precipitation, look for winds to increase in most areas with the strongest and gustiest wind speeds near Mt Hood. Showers may linger into the morning hours for a few locations, but Wednesday seems to be a repeat of today. Look for increasing sunshine, passing high clouds, and light to moderate winds across the mountains.
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 to mostly sunny. Calm winds becoming light NW.
Tuesday
Night
Low clouds with light NW winds.
Tuesday
Partly to mostly cloudy with spotty very light precipitation. Winds becoming Light W in the afternoon.
Tuesday
Night
Cloudy with isolated showers. Light W winds becoming calm overnight.
Tuesday
Cloudy with isolated very light showers. Light NW winds.
Tuesday
Night
Cloudy with isolated showers. Light to moderate WNW winds deceasing overnight.
Tuesday
Becoming partly to mostly sunny, with low clouds. Light NW winds.
Tuesday
Night
Mostly cloudy with isolated showers. Light to moderate NW winds.
Tuesday
Low clouds with sun breaks possible. Isolated very light precipitation possible in the morning. Light W winds.
Tuesday
Night
Cloudy with isolated showers. Light to moderate W winds.
Tuesday
Low clouds with isolated very light showers. Some sun breaks possible in the afternoon. Light to moderate NW winds.
Tuesday
Night
Cloudy with scattered showers. Light to moderate NW winds increasing slightly overnight.
Tuesday
Mostly sunny with spotty low clouds. Light to moderate N winds becoming NW in the afternoon.
Tuesday
Night
Increasing clouds overnight with a few flurries possible near the crest. Moderate W winds becoming NW overnight.
Tuesday
Mostly sunny with some low elevation clouds. Light to moderate N winds becoming NW.
Tuesday
Night
Increasing clouds with a few flurries possible near the crest. Moderate NW winds.
Tuesday
Mostly sunny with a few spotty low clouds. Light to moderate N winds becoming NW.
Tuesday
Night
Increasing clouds near the crest. Moderate NW winds.
Tuesday
Mostly sunny with a few low-level clouds. Light to moderate N winds.
Tuesday
Night
Increasing clouds and a few isolated showers. NW winds increasing significantly and becoming very strong and gusty.
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).