Avalanche Forecast

Light to moderate showers Friday night should taper off after midnight with only isolated light snow showers expected on Saturday. The same trend is expected for the moderate to occasionally strong W-SW winds forecast for Friday night with winds easing considerably on Saturday.

Strong winds Friday and Friday night will have built fresh wind slab on lee aspects mainly near and above treeline. Watch for new wind slab in the upper portion of the below treeline band. Easterly aspects will be highlighted in the elevation/aspect diagram but watch for firmer wind transported snow on a variety of aspects.   

Despite the cooling trend, new and shallow storm slab instabilities may be locally sensitive. Storm slab size will range from small to large in the Mt. Baker area where more snowfall is expected.  

For areas west of the Cascade crest including Mt. Baker, Crystal and Mt. Rainier, wet slabs will not be listed as they are very unlikely due to the cooling trend. However, for one more day avoid travel below unsupported slopes, especially below treeline, with the low likelihood/high consequence of large wet slab avalanches in mind. Wet slab releases are hard to predict and can happen a day or two after peak warming and rainfall.   

Weather and Snowpack

A strong storm cycle Friday 2/3 through Monday 2/6 produced 3-5 feet of snow along the west slopes of the Cascades. 

A strong plume of moisture brought heavy rain to the west slopes of the Cascades (Mt. Baker, Crystal and Paradise) Wednesday evening through Thursday with a mix of snow, freezing rain, and rain seen in the Cascade Passes. A strong cold front swept through the Cascades mid-day Thursday with bands of light to moderate showers in SW flow following the front. A switch to westerly flow brought a bump up in temperatures in the Cascade Passes Thursday afternoon and night.  

Friday was windy with a slow cooling trend during the day. Light showers increased and generally became moderate in the afternoon. The Mt. Baker area had received the most snow with 13 inches recorded at Heather Meadows through 6 pm Friday.  

Recent Observations

North

Mt. Baker pro-patrol reported that the cooling trend had quickly locked up the recent wet snow within the ski area. Strong W-SW winds were transporting snow to lee slopes and not bonding well to the new crust. 

Central

Stevens Pass pro-patrol and DOT reported a natural avalanche cycle Thursday morning with major paths running D2 - D3. The pro patrol also observed some natural activity off Skyline Ridge and heard an unusual report of a path running to the Nordic road in Mill Valley. A bit east of Stevens Pass, a large avalanche off of Dirty Face Peak knocked in a garage door of a house on the north shore of L. Wenatchee around 1130 am Thursday. 

On Thursday, Alpental pro-patrol reported a breakable freezing rain crust (i.e. less stout than the 1/17 IFrc) that made for tough ski conditions. Cornices along ridgelines weakened during the warming with some cornice breaks observed in the early afternoon. The cornice failures triggered some D1-D2 storm slabs below ridges.  

South

Crystal pro-patrol observed several loose wet slides up to size D2, all aspects, within the ski area Thursday. No large slab releases were produced with explosives Thursday afternoon. Wet slabs estimated to be about 1 ft deep were observed from the ski area in Pickhandle Basin. 

White Pass reported similar conditions as the other Passes, with a freezing rain crust up to at least mid-mountain and very strong W-SW winds atop Pigtail Peak through Friday. 

Crystal pro-patrol reported minimal results during control work Friday except... when they used a 25 lb explosive on Powder Bowl. The result was an 8 ft crown, 150-200' wide, that broke down to facets 3" above the ground. While this slide isn't relatable to human triggering, everyone loves a photo of a big avalanche.

 P. Dale, Crystal Mt Pro-patrol, 2-10-17