Mountain Weather Forecast

Weather Synopsis

The latter half of the Holiday week brings more wind, unseasonably mild weather, and some precipitation.

A deep upper-level low offshore continues to drive decreasing moderate E flow through the evening hours. A secondary front that is known in the meteorological lexicon as a "bent-back occlusion" arrives Wednesday night behind the initial frontal passage. These bent-back occlusions have a history of windstorms in the Pacific Northwest, but this one tracks far enough offshore that we just get a glancing blow. Hurricane Ridge and Mt Baker can expect some hours of 30 mph winds with some 50+ mph gusts before the low exits into British Columbia. The tight pressure gradients driving these winds will also have enough moisture to produce moderate rain and snow for the Olympics, Mt Baker, Mt St Helens, and Paradise overnight. In the case of Mt Baker, the more intense precipitation extends through the morning hours on Thursday. West of the Cascade Crest, snow levels hover around 5000 ft (a touch lower than on Wednesday). However, persistent SSW flow has eroded significant amounts of the cold air pool east of the Cascades, so lighter precipitation south of Highway 2 arrives as a wintry mix or rain at lower elevations east of the Cascade Crest.

Rain and snow shower activity taper on Thursday as a ridge builds across the interior. Expect mostly cloudy skies to linger.

Another relatively deep upper low moves into our offshore waters Thursday night and Friday, driving another round of increasing E winds, which could reach moderate strength on Friday. SSW flow continues to spin limited moisture into the Olympics at times with some very light upslope rain, snow, or wintry mix possible at times along the east slopes of the Cascades.