THIS SNOWPACK SUMMARY EXPIRED ON January 8, 2016 @ 11:00 pmSnowpack Summary published on January 8, 2016 @ 6:00 am
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.
As mentioned in the summary I posted on New Years Eve, their is some existing potential to trigger a wind slab at upper elevations. Slabs are likely to be small in size and destructive potential. However, give steep leeward slopes a hard look before commiting to riding or skiing in these areas. Also, pay close attention to the effects of solar radiation as well as the terrain and potential consequences of being caught by a slide.
SOLE (Selkirk Outdoor Leadership & Education) will be hosting a AIARE Level 1 (Decision Making in Avalanche Terrain) course on January 16-18th as well as January 22-24. For info go to http://soleexperiences.org/register-sole-experiences/
DTSAR will be hosting a "Introduction to Avalanches Course" on January 22nd and 23rd in Libby. For info contact Terry Crooks at 293-1618.
New years day I went for a tour in the Eastern Cabinet range which took me across both north and south aspects up to an elevation of 7,700'. I observed widespread surface hoar development on shaded aspects ranging from 4,500' up to 6,500' in elevation. The surface hoar was not prevalent above the inversion layer or on any aspect that was recieving solar radiation. Above the inversion layer there was substantial warming which created some roller balls as well as a thin crust. Just below ridgeline there were some small wind slabs that had released naturally but posed minimal hazard.
Yesterday (January 7th) my partner and I traveled to the St. Paul Peak area in the southern Cabinets. On the climb into Cliff Lake we found obvious signs of warming, and recent solar radiation had broken down much of the surface hoar as well as developed a light crust. We dug a pit at 7,000' on a sheltered southwest aspect. Extended column test produced fracture without propagation across the column with hard force (ECTN28), 40 cm below the surface on a stellar crystal layer (new snow). This layer did not propagate or show any signs of reactivity on test slopes or wind loaded areas as we traveled further up the mountain. Upper elevations showed signs of light northeast winds. Data from the Chicago Ridge Snotel site combined with travel observations show that wind loading and snow transport has been minimal over the last 7 days.
Weather and CURRENT CONDITIONS
Weather for the past 7 days have delivered minimal amounts of additional snow to the Kootenai region. This combined with relatively warm daytime temps and solar radiation above the inversion layer have signicantly decreased the distribution of surface hoar found developing on the Kootenai snowpack. These same factors have also resulted in the development of a thin sun crust 1-2 cm in thickness. National Weather Service predictions for the Kootenai area are calling for some light snowfall through Friday followed by a decrease in temperatures and light east winds. With the potential for the occasional sunny break, backcountry travelers should pay close attention to how the sun is affecting the snow stability over the next week.
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.
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