Avalanche Forecast

Snow showers will continue Sunday with moderate ridge top winds. Temperatures should remain cool.

Recent storm and wind slabs may continue to build and storm layers from Saturday and Saturday night will have little time to settle or stabilize by Sunday. 

Either wind or storm slabs should remain sensitive and likely to trigger. A variety of aspects from north to southeast facing lee slopes will continue to be loaded throughout the day Sunday, as well as earlier loaded southwest aspects.  

Dangerous avalanche conditions are expected near and above treeline requiring conservative decision-making and cautious routefinding.

Travel conservatively by staying off, or below steeper slopes and avoiding the wind loaded terrain near and above treeline.

Persistent slabs now seem unlikely to trigger in the NE zone, but we will wait for more information before dropping this avalanche problem all together. Look for obvious clues to turn around like whumpfing or shooting cracks as evidence that persistent slab is an avalanche problem in the near and below treeline zones.  

Use extra caution if traveling into the above treeline zone as there have not been any recent observations from this elevation band. 

Snowfall over the east slopes the first week of December was about 1-4 feet. Then an atmospheric river arrived early in the week with additional snow in the northeast zone, rain in the southeast zone, with a transition in between in the central east zone. Almost 4 inches of water accumulated in 48 hours for Washington Pass and Holden ending early Thursday morning. 

Avalanche and Snowpack Observations 

We have varied conditions along the Cascade east slopes!  The forecast discussion is the same for the east slopes, but the danger ratings and problems differ by zone. 

A regionally deep snowpack exists in the northeast Cascades. Recent heavy precipitation along with a warming trend has likely thoroughly tested the buried persistent weak layers from mid-November. Current avalanche problems are more likely to have shifted to storm related weaknesses in the northeast zone. Persistent slabs now seem unlikely to trigger, but we will wait for more confirmation before removing this avalanche problem all together.  

NWAC observer Tom Curtis was at Blewett Pass in the central east zone Wednesday and found sudden collapse test results in faceted snow at the November crust 15 cm from the ground. On Thursday, Tom found similar sudden collapses with buried surface hoar averaging 50 cm down at 5100 ft on the north side of Mt. Cashmere. More importantly, Tom experienced whumpfing as this layer collapsed and heard a natural avalanche release far from his observation location. We don't know how this layer fares as one moves further up in elevation, thus we'll forecast conservatively until more information is known about lingering PWLs in the central-east Cascades.  Further east in this zone, Mission Ridge pro patrol did not find the recent storm snow particularly reactive during control work Friday morning, nor was there any evidence of lingering weak layers. 

Saturday, Tom Curtis and Ian Nicholson travelled to Jove Peak near Rainy Pass east of Stevens Pass. There was no evidence of the PWL in observations up to 5000 feet on S-W aspects. As of Saturday there was about 35 cm of storm snow over the crust.  

The southeast zone should have a much shallower and more stable snowpack affected by recent rain and warm temperatures. We have not received any observations from this zone.