Mountain Weather Forecast

Weather Synopsis

A cold upper low off just off the Washington coastline continues to rotate moisture into the region on a light S flow. The original vertically stacked surface low retrogrades slightly westward Saturday night as upslope moderate snow tapers for the southern Washington volcanoes as well as the SE slopes of the Olympic Mountains. Meanwhile, a secondary surface low forms in the Columbia Basin overnight. The new low should enhance support for light to occasionally moderate upslope ENE flow along the east slopes of the Cascades. The focus of the light snow shifts from areas south of I-90 to I-90 northward by late evening. In between the two surface lows, a zone of wind shear sets up and should be associated with a band of moderate snowfall. Exactly where this sets up will be difficult to predict precisely, but it looks like it will linger over the central Cascades (both sides) from the late evening hours through early Sunday. This band may drift northward into the Methow Valley area later Sunday with light snowfall tapering overnight. The snow event along the east slopes should bring the heaviest snow to Mission Ridge which can expect around 12" of snow Saturday night through Sunday while other parts of the eastern mountains might expect 5-10".

Outside of the band of precipitation in the central Cascade on Sunday, expect some partial clearing during the late morning hours, but convective cumulus clouds will build and may produce some more intense graupel showers during the afternoon and evening. Skies partially clear with limited snowfall overnight. Expect partly cloudy skies Monday morning with another build-up of convective snow showers more focused on the E slopes of the Cascades with light low-level E winds.

Snow levels vacillate between just above sea level in the early morning hours up to around 1500 ft each afternoon.

2:10 PM: Fixed an issue with the temperature forecast