A vertically stacked upper-level and surface low is moving southward off the Oregon Coast. A band of very light snow wraps around the low into the Oregon and southern Washington Cascades early Thursday. Light SE ridgeline winds shift W by the afternoon, with enough cold air aloft for some cloud buildup and isolated light snow showers (but less than recent days). An incoming shortwave ridge shifts upper-level flow northerly overnight. When combined with clearing skies, expect a cold Thursday night with 5000 ft temperatures dropping into the 10s in most areas.
The transient ridge should bring fair weather to most areas on Friday. Another closed low dropping southward from the Gulf of Alaska could keep some light snow shower activity in the forecast for Mt Hood, but less than an inch of snow is expected. Southerly flow should allow temperatures to warm a few degrees relative to Thursday.
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
Partly cloudy with isolated snow flurries.
Thursday
Night
Gradually clearing skies. Cold.
Thursday
Partly cloudy with isolated snow showers in the afternoon.
Thursday
Night
A few clouds. Cold.
Thursday
A slight chance of light snow in the morning with isolated snow showers in the afternoon.
Thursday
Night
A few clouds. Cold.
Thursday
Periods of light snow in the morning with isolated snow showers in the afternoon.
Thursday
Night
Snow flurries in the evening with gradual clearing overnight.
Thursday
Periods of light snow in the morning with isolated snow showers in the afternoon. Light and shifting ridgeline winds. Light E winds shift W at the Pass by late morning.
Thursday
Night
Snow flurries in the evening with gradual clearing overnight. Light ridgeline and W wind at the Pass.
Thursday
Periods of light snow in the morning with isolated snow showers in the afternoon. Light and shifting ridgeline winds. Light E winds shift W at the Pass by late morning.
Thursday
Night
Snow flurries in the evening with gradual clearing overnight. Light ridgeline and W wind at the Pass.
Thursday
Snow flurries or light snow showers, mainly in the afternoon.
Thursday
Night
Partly cloudy in the evening, clearing skies overnight.
Thursday
Snow flurries or light snow showers, mainly in the afternoon.
Thursday
Night
Partly cloudy in the evening with a few snow flurries. Clearing skies overnight.
Thursday
Periods of light snow or light snow showers, mainly in the afternoon.
Thursday
Night
Partly cloudy in the evening with a few snow flurries. Clearing skies overnight.
Thursday
Periods of light snow in the morning, then light snow showers. L
Thursday
Night
Isolated snow showers. Light to moderate 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).