Avalanche Forecast

Dangerous avalanche conditions will persist on Friday mainly above treeline due to additional light snowfall, an uptick in wind transported snow near and above treeline, and cold temperatures preserving recent storm instabilities. Due to lower density surface snow available for transport and moderate W-SW winds forecast, wind slabs may develop below treeline or further downslope than you might expect Friday.  Avoid travel on slopes if you encounter wind stiffened surface snow, especially on steeper exposed terrain and steep roll-overs. Give safe margins near and below growing cornices.

Persistent weak layers may be found in isolated areas in the northeast and central-east zones. Greater margins of safety are required due to the uncertainty surrounding the distribution of these layers, especially when considering consequential terrain.

There's plenty of good snow out there, so maintain a conservative approach to terrain selection. 

An extended storm cycle continues, sharing (almost) equally with the east slope locations! Total storm snow of 2 to 3.5 ft is typical, and the recent storm snow overlies a melt-freeze crust buried Jan 16th. The bonding continues to be favorable to this crust from most recent observations.

Observations above treeline have been limited leading to a higher level of uncertainty in this terrain.

Buried surface hoar was observed on the 1/16 crust in the Cascade East - Central zone on Wednesday, January 17th. The layer was also found on the crust in the Twisp River drainage on Monday, January 22nd, but faceted grains below the crust were also concerning. The crust/PWL interface were the suspect culprit for a large avalanche on Sunday 1/21 in the Cascade East-North zone. This layer will need to be watched during the upcoming stormy period as the extent and distribution of these weak layers remain uncertain and likely confined to isolated areas.

Snowdepth still decreases substantially east of the Cascade crest. In many areas below treeline, there has not been enough snow to present an avalanche danger.

Note - The NWAC Washington Pass station is back online - nice work DOT! Precipitation and other sensor repairs to be planned...

Observations

North

On Thursday, NCH observed evidence of numerous recent wind slabs that had released in steep terrain above treeline in the Washington Pass area. 

Wednesday, Jan 24th, NCMG observations on Delancy Ridge found nearly 3 ft of low cohesion storm snow in sheltered terrain below treeline with no avalanches noted. No reactivity was found at the 1/16 interface with the melt-freeze crust. 

On Monday, snowpit tests by a snow professional on a SE aspect near treeline in the Twisp River Valley gave sudden collapses within faceted grains below the 1/16 crust. Test results on a NE aspect yielded consistent sudden planar results above the 1/16 crust with partially decomposed surface hoar on the interface.

NWAC received a second-hand report of a large skier-triggered avalanche on west-facing slope (likely near treeline) on Abernathy Peak in the upper Twisp River drainage. The avalanche propagated widely and was suspected to have failed on the 1/16 crust. 

Central

A public observation from Wednesday in the Blewett Pass area identified basal facets at the bottom of the snowpack and surface hoar above the most recent crust. Snow cover was still regionally low in this area. Small skier triggered wind slabs were noted and rain briefly reached up to 5000' Wednesday morning. 

Buried surface was found in the Icicle Creek drainage over the 1/16 crust over a week ago up to 6800 ft.  

South

No recent observations