Mountain Weather Forecast

Weather Synopsis for Saturday & Thursday

Our active pattern continues with the second low pressure system in 24 hours for the Pacific Northwest sliding down over the area in NW flow aloft. Precipitation has become moderate to locally heavy over the Cascade Passes this morning and precipitation rates in general should increase through the early afternoon hours.  The low pressure center currently off the northern tip of Vancouver Island will pass into southern British Columbia this afternoon with the trailing front passing through the Cascades in the early afternoon. A swath of warmer air will push into the mountains from about Stevens Pass to Mt. Hood, with the north Cascades having a more muted warming trend. Snow levels should peak around 6000 ft at Mt. Hood, 4500 ft in the Crystal Paradise/Mt. Rainier area and 4000 feet for Stevens/Snoqualmie Pass mid-day. The frontal passage will be followed by an increase in westerly winds in all areas but most pronounced from Snoqualmie Pass and southward this afternoon. Expect sharp cooling this afternoon behind the front. 

The quasi-stationary Pacific upper level ridge parked offshore will retrograde to 145W Saturday night and Sunday. This will open the door for the coldest air of the season to begin to inflitrate from the interior.  As the upper level trough digs over the Pacific Northwest and northern California Sunday, a weak surface low pressure system off the Washington/Oregon coast will invigorate snow shower activity for the Mt. Hood area and the south Washington Cascades while a slow drying trend takes place over the northwest and central-west Cascades. Colder air being drawn across the Strait of Juan de Fuca will lead to upslope snow showers in the Hurricane Ridge area. Upslope snow showers also look likely along the east slopes of the Cascades on Sunday.

Shower activity will wane Sunday night as the trough digs over the intermountain West and the flow aloft turns northerly.