Idaho Panhandle Avalanche Center
This message is available by calling (208) 765-7323 or toll-free at 1-866-489-8664.
Good Morning, this is Kevin Davis with the Idaho Panhandle Avalanche Center. This advisory is valid for today, January 7th, 2011, with an outlook for the 8th and 9th. This report does not apply to local ski areas within the forecast region and the hazard rating will remain valid through midnight, January 7th. Special thanks to Idaho Parks and Recreation for sponsoring this morning’s avalanche advisory. Thanks to Silver Mountain Ski Patrol for sending us pit data from the Mountain.
Another big swing in the weather has brought a significant warming trend to the mountains of North Idaho. At 5AM regional snotel sites are showing temperatures hovering near and above the freezing mark indicating that the magic line is hovering between 4-5,000 feet. This is influencing the peculiar North Idaho phenomenon where snow falls at above freezing temperatures. 24 hour snowfall shows that most locations picked up several inches of new snow with the highest amounts falling in the Lookout Pass area. Snotel depth measurements may be misleading since heavy snow is compressing the light snow that fell this week. We can expect more snow today and this weekend with the southern portion forecasted to receive the greatest amounts. The avalanche conditions will remain for the outlook period.
Avalanche conditions for the Selkirk and Cabinet Mountain Region are rated as MODERATE on all aspects steeper than 30 degrees above 4,500 feet. Natural avalanches are unlikely and human triggered avalanches are possible. Avalanche conditions are rated as LOW on aspects less than 30 degrees.
On our tour around the Cabinet Mountains yesterday we found that a thin crust layer had formed from freezing rain on Wednesday evening. The crust was breakable and covered several inches of light snow which buried last weekend’s surface hoar. Shears were easy and consistent on this weak layer that was about 6 inches deep on sheltered aspects and 3 inches on exposed aspects. Below this the pack is fist density, very light, all the way down to the decomposing crust layer buried 2 feet deep now. You’ll find the crust to be very weak and sugary. Warmer temperatures for the near future won’t bode well for this layering and if we get rain, that will weaken the pack further. Watch for heavier snow sloughing and potentially slabbing up on the thin ice crust.
Avalanche conditions for the St. Regis Basin and St. Joe Mountain Region are rated as CONSIDERABLE on windloaded aspects steeper than 32 degrees above 4,500 feet. Natural avalanches are possible and human triggered avalanches are probable.
Avalanche conditions are rated as MODERATE on aspects less than 32 degrees and where not windloaded.
In their pit tests around Lookout Pass yesterday, Carole and Dan found weak layers associated with changing density in the new snow at about 6 inches deep. Heavier snow has not bonded well with underlying layers and with new snow accumulations will be undergoing additional stress. Silver Mountain Patrol found fist density snow 2 feet deep shearing cleanly but with moderate force on a layer of dense rounded grains. They also noted the decomposing crust just over 3 feet deep. Rain will rapidly decrease stability. They did note that the buried surface hoar was harder to shear but failed cleanly with multiple jumps on the Rutschblock test. Shoshone county is under a winter weather advisory that is in effect from 10PM this evening to 4PM Saturday. There is a 100% chance of 2-4 inches tonight and 3-5 inches on Saturday. SW winds will be loading NE-SE aspects so look for instability in windloaded new snow.
The next advisory will be issued next week on January 14th.
The State of Idaho Parks and Recreation Department in cooperation with the IPNF-AC, is conducting (Free) avalanche workshops for snowmobilers this winter in Coeur d’ Alene on January 14th and 15th, St. Maries January 28th and 29th, and in Bonners Ferry February 11th and 12th. For more information, go to the Idaho Parks and Recreation Department website at www. parksandrecreation.idaho.gov, or call Marc Hildesheim, North Region Trails Specialist, at (208) 769-1511.
The Panhandle Avalanche Center in Sandpoint and Sandpoint Parks and Recreation is sponsoring free avalanche workshops for all snowgoers this winter. Our next course will be, "What we can learn from ten years of avalanche accident review in North Idaho", offered 2/9/11. These are offered at the new Forest Service Building in Sandpoint at 6PM and are Free to the public. For class schedules in the Silver Valley contact Dan Frigard at 752-5130. So far Dan has a workshop scheduled for January 22nd at 9AM and will be an interactive class focusing on avalanche dynamics. In Avery, contact Ed Odegaard at 245-6209.
If you have a group or club that is interested in more education on avalanche safety we will be available for free avalanche awareness classes beginning in December, so feel free to give us a call. As usual we would appreciate hearing from anyone who happens to observe any recent avalanche activity while out in the backcountry or just wants to let us know what is going on in their area.
Have a safe and pleasant weekend.