January 2, 2012 Avalanche Advisory

Above 6000 feet on wind-loaded terrain steeper than 35 degrees the avalanche danger is CONSIDERABLE.  Natural avalanches are possible and human triggered avalanches probable.  Dangerous avalanche conditions exist on many north to south facing slopes.

The avalanche danger is MODERATE on other slopes.  Natural avalanches are unlikely, human triggered avalanches are possible.  There is LOW avalanche danger below 5000 feet.  Natural and human triggered avalanches are unlikely.

Good morning backcountry travelers, this is Steve Karkanen at the West Central Montana Avalanche Center with your backcountry avalanche advisory for January 2, 2012.

Weather and Snowpack Analysis

The New Year brought a short break in the weather allowing us to get out and see some of the terrain we’ve been concerned about this past week.  On a tour in the Rattlesnake we saw evidence of several large and small natural avalanches that released sometime during the storm December 28-30.  As mentioned in our warning, high winds determined which slopes would be brought to their breaking point. Northeast to east aspects are the most heavily loaded with north and south shoulders having more varied loads. The west half of the compass has been scoured hard in many locations.

We experienced some collapse noise and fracture propagation in open spots but nothing like we witnessed last Thursday through the weekend.  All our stability tests indicate that we still have dangerous avalanche conditions on steep wind loaded terrain.  South and north aspect slopes at 7900 feet are the weakest here with consistent failures at the same level.  A hard slab overlies faceted snow found at the mid-point of the snowpack.  This video of an extended column test shows what we found in our pits yesterday:   New Years Day.  We received a report of similar conditions in the southern Swan range east of Seeley Lake, Montana.

Dudley and Tim rode out to a higher elevation site near Rocky Point and found a similar snowpack structure but stronger overall stability.  They still felt that steep wind loaded terrain needs a couple more days to adjust to the new load.  The facets are not as pronounced here or at any of the other Bitterroot observation sites.  Observers on Saddle Mountain Saturday were seeing more stable conditions than experienced Thursday.  Everyone’s gut feeling is that overall conditions are now at CONSIDERABLE on any wind loaded slope steeper than 35 degrees above 6000 feet.

Weather Forecast and Avalanche Outlook

High elevation temperatures will warm up Monday with a chance for a return of light snowfall Monday night and Tuesday.  The next system with a good chance for snow is expected Wednesday night with light to moderate snowfall amounts.

Expect avalanche danger conditions to remain similar with slow improvement over time.  We have persistent weak layers that will unfortunately remain with us for several days or weeks.  Any time a new load is added either by new snow, wind or by us, these weaknesses will be put to the test.  You really have to pay close attention to conditions this year.  This is the kind of snowpack that gives avalanche workers nightmares.

Avalanche Accident near Cooke City, MT.

Two separate avalanches claimed the lives of a skier and a snowmobiler Saturday near Cooke City, MT.  Avalanche specialists from the Gallatin NF Avalanche Center are investigating these incidents and will post details once they complete their investigation. Our sympathies go out to the friends and families of the individuals involved.

We continue to receive great reports from many of you. These are very valuable in that they help us provide better information.  Send your observations via our on-line form or simply drop us a line at [email protected]

Have a safe and Happy 2012!  Tim Laroche will issue the next advisory on Friday, January 6.