Mountain Weather Forecast

Weather Synopsis for Wednesday night through Tuesday

The weather should be relatively quiet Wednesday night, Thursday, and Thursday night. A dry and decreasing WNW flow aloft keeps some moisture trapped in the low levels of the atmosphere. Very weak perturbations should wring out some very light snow showers and convergence at times, but trace amounts of snow accumulation are expected. The bigger impact will be the cloud cover and visibility, but the timing of convergence bands and periods of cloudiness remains difficult. Expect partly to mostly cloudy skies with light snow flurries at times along the west slopes of the Cascades with clear skies further east. Temperatures continue to cool on Wednesday afternoon through Wednesday night behind the departed front that passed early Wednesday. The resultant freezing levels should remain slightly cooler than average.

A stronger developing low detaching from the main flow drops south along the British Columbia coastline Thursday night and will be a complex system. The low spreads light snowfall into NW Washington State by Friday morning which increases to light to moderate as it transits off the Washington Coast during the day Friday, spinning moisture mainly into the Washington Cascades and Olympics with a rapid switch from SW to increasing moderate E or ENE flow that favors the east slopes for snowfall.  At this time it looks like 4-8" of snow should fall by the end of the day Friday for Hurricane Ridge, the Mt. Rainier area, Snoqualmie, Steens, Mission Ridge, with 2-4" in the North Cascades and Mt. Hood areas.

Strong moderate low-level Fraser outflow develops late Thursday night, spreading cold air into the Puget sounds lowlands. These winds intensify to become strong during the day on Friday, peaking Friday evening and don't fully decrease until sometime on Sunday. Expect these winds to enhance snowfall totals on the north slopes of the Olympic Mountains (Hurricane Ridge area) well after the low passes to the south.