A frontal system that sagged south over Washington last night is lined up over the southern Washington Cascades and northwest Oregon this morning. Steadier snow from the central Cascades to Mt Hood will transition to showers from north to south this morning, remaining heaviest over Mt. Hood along with the strongest winds. An upper level feature rotating in from the upper level low parked off the central B.C. coast, will renew moderate showers for the Olympics this morning and then for the Cascades this afternoon. Heavier snowfall is expected for the Mt Baker area Monday afternoon in this pattern. This feature will also cause a spike in S-SSW winds for the northwest Cascades. After days of easterly flow in the Passes, this feature will also cause a switch from east to west winds around 12pm-2pm timeframe along with a subtle bump in snow levels this afternoon.
Showers will continue Monday night but become lighter in nature, except moderate near Mt. Hood. Another upper-level disturbance will pass through Tuesday morning to spread increasing showers over the Olympics and Cascades. A developing low pressure system will approach the central Oregon coast Tuesday afternoon, spreading steadier snow inland. WNW flow over the Washington Cascades will help keep light to moderate snow showers throughout the day.
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
Moderate snow showers this morning becoming light to occasionally moderate this afternoon.
Monday
Night
Light and scattered snow showers.
Monday
Light to occasionally moderate snow showers this morning, becoming moderate this afternoon. Increasing ridgeline winds mid-day.
Monday
Night
Moderate snow showers becoming light late in the evening.
Monday
Light to occasionally moderate snow showers this morning, becoming moderate this afternoon. Increasing ridgeline winds late morning.
Monday
Night
Light to occasionally moderate snow showers becoming light late in the evening.
Monday
Light to occasionally moderate snow, becoming light snow showers later in the morning. Ridgeline winds and showers increasing this afternoon.
Monday
Night
Light to occasionally moderate snow showers becoming light late in the evening.
Monday
Light to occasionally moderate snow, becoming light snow showers later in the morning. Ridgeline winds and showers increasing this afternoon. Light to moderate east winds in the Passes becoming west in the afternoon.
Monday
Night
Light to occasionally moderate snow showers becoming light late in the evening. Variable winds at Pass level.
Monday
Light to occasionally moderate snow, becoming light snow showers later in the morning. Ridgeline winds and showers increasing this afternoon. Light to moderate east winds in the Passes becoming west in the afternoon.
Monday
Night
Light to occasionally moderate snow showers becoming light late in the evening. Variable winds at Pass level.
Monday
Light to occasionally moderate snow showers this morning becoming scattered showers late morning. Ridgeline winds increasing in the afternoon.
Monday
Night
Light to occasionally moderate snow showers becoming scattered light showers late in the evening.
Monday
Light to occasionally moderate snow showers this morning becoming scattered showers late morning. Ridgeline winds increasing in the afternoon.
Monday
Night
Light to occasionally moderate snow showers becoming scattered light showers late in the evening.
Monday
Light to occasionally moderate snow, becoming light snow showers later in the morning. Strong ridgeline winds.
Monday
Night
Light to occasionally moderate snow showers becoming scattered light showers late in the evening.
Monday
Moderate to heavy snow and strong winds decreasing during the day and becoming moderate snow showers.
Monday
Night
Light to moderate snow showers. Moderate to strong 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).