A broad upper-level trough gradually slides eastward across southern Canada. The PNW lies in cold WNW flow on the back side of the trough with the region drying out from post-frontal showers. A few snow showers or flurries may linger for the central Washington Cascades but are expected to come to an end by around 8 AM.
Mountain temperatures remain cold across the region with overnight lows ranging from below zero in the Methow to the upper 10s in the Mt. Hood area. Temperatures should rebound slightly today, but temperatures remain well below seasonal norms. Expect more cloud cover from around the Mountain Loop southward.
Flow turns NWerly overnight as a ridge builds into the near-shore waters, allowing for partly cloudy to mostly clear skies and strong radiational cooling. Moderate E flow develops with E winds increasing into the moderate range through the mountain gaps. Bitterly cold temperatures continue.
On Thursday, clouds increase as a shortwave trough moves into the near-shore waters with the weak ridge axis over our region. Light snow should start up around Mt. Hood by the end of the day. Expect strong E winds at low levels to create bitterly cold wind chills through mountain gaps, with mostly light southerly winds aloft.
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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Wednesday
Partly to mostly cloudy. Cold.
Wednesday
Night
Partly cloudy. Cold.
Wednesday
Mostly sunny. Cold.
Wednesday
Night
Mostly clear. Cold.
Wednesday
Mostly cloudy in the morning, transitioning to mostly sunny by the afternoon. Cold.
Wednesday
Night
Partly cloudy. Cold.
Wednesday
Mostly cloudy in the morning with a chance of snow flurries. Becoming partly cloudy during the afternoon.
Wednesday
Night
Partly cloudy. Cold.
Wednesday
Mostly cloudy in the morning with a chance of snow flurries. Becoming partly cloudy during the afternoon. Cold. Light ridgeline winds with variable pass-level winds turning light easterly.
Wednesday
Night
A few clouds. Cold. Increasing ridgeline and E winds at the pass transitioning from light to occasionally moderate.
Wednesday
Mostly cloudy in the morning with a chance of very light snow showers early. Becoming partly cloudy during the afternoon. Cold. Light ridgeline winds with variable pass-level winds turning light easterly.
Wednesday
Night
A few clouds. Cold. Increasing ridgeline and E winds at the pass transitioning from light to moderate.
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).