Dec 9, 2010 @ 10:45 pm

December 10, 2010 update

Hello! This is Steve Karkanen with the December 10th update from the West Central Montana Avalanche Center in Missoula.

Although it’s not officially winter we’re well into what could very well be a record breaking snow year with snow totals at or exceeding yearly norms for early December. And more is on the way…

The National Weather Service Forecast Office in Missoula has issued a winter storm warning valid for our area from 5PM Thursday to 11PM Friday. Storm snowfall totals may be impressive with 15-18” forecast for some of the higher terrain in the Bitterroot, Sapphire and Clearwater mountains.

Strong westerly winds at 25 mph will be associated with this system with gusts up to 40 mph.

The nature of this weather system alone will increase the avalanche hazard on many slopes. Leeward terrain will be the most dangerous for several hours during and immediately after the storm. But there is another factor that may come into play in a few isolated areas.

Earlier this week, during the clear sunny days and cold clear nights, many locations saw surface hoar develop which later gave way to very warm temperatures or was destroyed by wind prior to the light snow we received Wednesday and Thursday. While touring around Point Six yesterday I found little evidence of it until I dug a few pits. It was not present in most places but once found, it’s pretty obvious. But you have to dig a little to see it. It’s buried about 15cm deep and is most prevalent on N, NE and E aspects in areas sheltered from the wind.

It fails very easily during stability testing (on isolation on steeper terrain-see attached profile) and easily propagates fractures. Not a widespread condition and not a problem now but 8-10” of new or wind blown snow on these areas and it will be a big problem. Certainly worth looking for if we do get the big dump.

Stay tuned!

Avalanche Transceiver Training Parks

All 3 Beacon Parks are now operational.

Lolo Pass

The Lolo Pass park is now available 7 days a week as it is no longer necessary to check out the control box from the Visitor Center Staff. It is stationary and will remain in the same spot all winter. Please inform the Visitor Center Staff if you encounter problems with the controls. Organized groups who want to use the site for an educational or training program need to contact Buffie Cerutti at the Powell Ranger Station (208) 942-3113 regarding special use permit requirements.

Montana Snowbowl

The Professional Ski Patrol at Montana Snowbowl set up a 3 transceiver park at the top of Snowbowl this week. The Snowbowl beacon park is located at the cutoff to the backcountry towards Point Six, just off the trail to Nutcracker. The control box is set up in the morning and taken down at sweep. If the park is not set up (there is a sign, a stand and a yellow waterproof box), users can check the control box out from the Snow Bowl patrol at the patrol shack at the top of the Lavelle lift. You must purchase a lift ticket or have a ski pass to access this park.

Lost Trail Powder Mountain Ski Area

New for 2009/2010 is a Beacon Basin training facility at Lost Trail Ski Area on Highway 93 at Lost Trail Pass. The training opportunity is available to anyone who coordinates with the Ski Patrol at Lost Trail. Please send a message to Steve Porcella at to arrange your Thursday – Sunday.

Please note that you must have a transceiver and a probe to use these sites.

More detailed information is available on our website here:

Twice weekly avalanche advisories begin next Friday, December 17.

If you do get out and want to send your snow observations to us we will gladly look at them. Public observations have become an important part of our program as they help fill the gaps in areas we don’t travel to. We’ve tried to make it easier for you by providing a form page with easy to navigate menus and room for narrative and an easy way to send a picture or video. And if you don’t want it posted just let us know and we’ll honor your request.


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.