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THIS SNOWPACK SUMMARY EXPIRED ON January 15, 2016 @ 11:00 pmSnowpack Summary published on January 15, 2016 @ 6:00 am
Issued by
Ben Bernall - Kootenai National Forest
Avalanche Character 1: Storm Slab
Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize.
Many locations across the Kootenai National Forest have recieved close to 12 inches of new snow that has come in with relatively warm temperatures and moderate southwest winds. These factors have created a denser and cohesive slab layer overlying softer and weaker snow. On some aspects (southerly and westerly) this hazard is further complicated by a crust layer that formed during the sunny/warm days of early January. Frequent collapsing and "whumpfing" was noted in todays travels across areas with this underlying crust layer. This "bullseye" data screams at us as an obvious sign of instability. Backcountry travelers would be wise to be CAUTIOUS AND CONSERVATIVE in choosing their terrain and travel routes until this new snow has had time to settle and bond to the underlying layers.
Avalanche Character 2: 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.
While the new snow presents a widespread potential hazard it is most reactive in locations exposed to the effects of wind. Todays travels took us into the Canuck Peak area where winds seemed to be moderate and southwesterly. As mentioned previously, this new storm snow was more cohesive and reactive on south and west facing aspects where the wind created a dense top layer that is also worsened by the crust layer on these same aspects. Considering that the Kootenai National Forest is a very large coverage area with minimal wind data available I would advise backcountry travelers to BE VERY CONSERVATIVE IN TERRAIN SELECTION and to PAY CLOSE ATTENTION TO CHANGES IN SNOW DENSITY AND THE EFFECTS OF WIND as you change aspects and elevations.
Snowpack Discussion
BOTTOM LINE: The current snowpack conditions are DANGEROUS, TRICKY AND POTENTIALLY MISLEADING. Please be cautious with decision making and encourage your partners to do the same.
On Wednesday, an avalanche accident occured in the St. Regis Basin near the Idaho/Montana border. Reports state that the avalanche caused injuries but no fatalities. This area is within the Idaho Panhandle National Forest Avalanche Center.
recent observations
Today Nate Stephens and I snowmobiled into the Spread Creek area of the Purcell Mountains and skied to the top of Canuck Peak. On our travels across south and west facing aspects we observed a fairly dense slab layer that showed some cracking in the skin track as well as some very audible "whumpfs". Stability tests produced a wide range of results which inspired very little confidence and simply proved that now would be an easy time to be lured into the notion that we are working with a safe snowpack. On some aspects and elevations conditions seem pretty stable underfoot and tests supported this, BUT as one moves around in elevation and aspect there are some very reactive pockets within the snowpack. Again, conditions are likely to vary greatly across the forecast area and CONSERVATIVE DECISION MAKING WILL BE ESSENTIAL THROUGH THE UPCOMING WEEEK.
Weather and CURRENT CONDITIONS
weather summary
In the past 48 hours the Kootenai has recieved as much as 12 inches of snow in many locations. Current weather forecasts for the region show that we will continue recieving snow through the weekend with relatively mild temperatures. Pay close attention to the weather forecasts this weekend and check the SNOTEL sites for snowfall and temperature data before heading into the mountains. The predicted weather conditions will likely increase the existing avalanche hazard through the weekend and possibly into next week.
Disclaimer
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.
