Northwesterly winds and plenty of low-level moisture will continue to push showers up into the mountains Monday, especially for the central and southern portions of the forecast area. Showers should be strongest near the southern volcanoes and underneath a Puget Sound Convergence Zone. This narrow band of precipitation will bring locally heavier snowfall to areas between Stevens and Snoqualmie Passes. As winds continue to turn more northwesterly, look for this feature to focus on the I-90 corridor. While a few showers will make their way east of the crest, generally locations along the east slopes of the Cascades will stay cloudy and dry.
Many areas are experiencing very strong winds this morning, creating locally stormy conditions. As the day goes on, wind speeds should decrease slightly. However, winds will still remain strong enough to blow snow and decrease visibility.
We're sitting just on the eastern edge of a high-pressure ridge growing in the central Pacific. As the main flow of the jet stream shifts to our east Monday night and turns the upper elevation winds in a more north-northwesterly direction, this should bring in colder and drier air from Canada. As a result snow showers will decrease across the region. While you may still encounter a few isolated showers, expect generally dry conditions. We could even see a few sun breaks by Tuesday afternoon.
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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Monday
Cloudy with scattered snow showers. Light to moderate WNW winds decreasing in the afternoon.
Monday
Night
Cloud with a few flurries possible. Light to moderate W winds increasing overnight.
Monday
Cloudy with snow showers. Moderate W winds becoming WNW.
Monday
Night
Cloudy with isolated snow showers. Light to moderate W winds increasing slightly overnight.
Monday
Cloudy with snow showers, heavy at times. A Puget Sound Convergence Zone impacting areas between Hwy 2 and I-90. Moderate WNW winds decreasing slightly in the afternoon.
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).