Dec 25, 2012 @ 7:25 am

Christmas Day 2012 Avalanche Advisory

Current backcountry avalanche danger is MODERATE on wind-loaded terrain steeper than 35 degrees and LOW in other mountain locations.  Remember – it is possible to trigger an avalanche during periods of moderate avalanche danger.

Merry Christmas!  This is Steve Karkanen with today’s avalanche advisory from the West Central Montana Avalanche Center.


Weather and Snowpack Analysis

Since Friday, area mountains have received 6-10 inches of new snow.  The higher peaks and ridges have been sand blasted by winds that reached into the 30’s Sunday.  These winds have been moving a lot of snow from one aspect to another forming wind slabs on leeward and cross-loaded terrain.  Many ridgelines have been scoured down to the old November snow surface and there are now wind slabs in places that may surprise you.  A good example of this occurred last Friday when a skier triggered an avalanche on a south facing slope near Hoodoo Pass.  No one was caught or injured but the individuals were spooked by the depth of the slab.

SNOTEL sites are indicating that a great deal of settlement has occurred the past few days and these wind slabs are proving to be stubborn in our stability testing.  It is worth taking the time to read the terrain to see where they may be present.

We’re also starting to see some facet growth near the surface and in areas where the snow cover is thin.  This is not a problem now but could become a weak layer once it is more deeply buried.


Weather Forecast and Avalanche Outlook

Temperatures this morning are in the teens and low twenties and we received another dusting of snow overnight.  The Missoula Office of the National Weather Service is forecasting a ridge of high pressure to build today with another system expected to move into the northern Rockies late tonight. The area south of the I-90 corridor has the best chance for snow with the heaviest amounts falling along the ID-MT border.  After Thursday, weather models are leaning toward high pressure building which could give us an extended dry period.

The avalanche danger is expected to remain similar throughout the next few days. If any location receives more than 6 inches of snow, expect to see it easily slough off 35 degree and steeper slopes.


Leaving the Ski Area Boundary

Last February, an avalanche just outside the Stevens Pass Ski Area claimed the lives of 3 people.  This happened in an area easily accessed from the ski area.  The New York Times recently published an account of the accident with details about the decision making of a large group of skiers and snowboarders who left the ski area to enjoy fresh powder in the backcountry.

Snow Fall: The Avalanche at Tunnel Creek.

This is a good reminder that when you leave the ski area boundary you are now in a backcountry setting and in many cases, in avalanche terrain.  This is certainly the case at many of the ski areas in western Montana. If you leave the ski area, you need to be prepared. That means having knowledge of avalanche terrain, the ability to make good decisions, having rescue gear like a transceiver, probe and shovel and understanding that you may be own your own for a long time if something goes sideways.  Even a minor injury or equipment failure can have life-threatening consequences.

We hope Santa left some rescue gear under the tree for you. If so, or if you want to get proficient with your transceiver, visit one of our BCA Beacon Basin transceiver training parks.

The Lolo Pass Beacon Basin is available 7 days a week and is located next to the Lolo Pass Visitor Center.  This park does not require you to check anything out, just go to the control box, read the directions and you are good to go.  We also have similar parks at the top of Montana Snowbowl and Lost Trail Ski Areas. You must have a lift ticket to access these parks.

Have a safe holiday!  I will issue the next avalanche advisory this Friday, December 28th.





This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but the information can help you make a more informed decision regarding travel in avalanche terrain for the next few days.

Our advisory area includes National Forest System lands in the Bitterroot Mountains from Lost Trail Pass north to Granite Pass, the Rattlesnake Mountains north of Missoula and the Southern Swan and Mission Mountains near Seeley Lake, MT. Avalanche information for the Lookout Pass/St. Regis Basin area is available from the Idaho Panhandle Avalanche Center.