Jan 29, 2010 @ 12:00 am

January 29, 2010 Avalanche Advisory

Hello! This is Steve Karkanen at the West Central Montana Avalanche Center with backcountry avalanche information for Friday, January 29, 2010.

Current Avalanche Danger

The avalanche danger is LOW at all elevations with the exception of recently wind-loaded terrain steeper than 35 degrees above 5000 feet where the avalanche danger is MODERATE.

Continued moderate temperatures and light snowfall continue to give our snowpack plenty of time to strengthen. Our high elevation snowpack is generally stable but isolated pockets of instability still exist. These areas of concern are recently wind-loaded slopes steeper than 35 degrees mostly at the higher elevations of the advisory area.

Weather and Snowpack Analysis

Most locations picked up another 2 to 4 inches of snow since Monday. High humidity the past 24-48 hours has helped surface hoar crystals form on top of everything making for some very enjoyable skiing.

Reports from the Bitterroot Mountains at Lost Trail Pass, Lolo Pass, Lookout Pass and the Rattlesnake Mountains all indicate continued strengthening of the weak layers described in earlier reports. We’re close to the point of not even mentioning them anymore since it takes so much force to make them fail, but we have yet to be tested by a big storm.

Our primary concern, once it begins snowing again, will be this current crop of surface hoar crystals. These 5-10mm size crystals tend to be our biggest avalanche problem once buried. Sun, warm temperatures and wind easily and quickly destroy these crystals when they are exposed, but when buried, they create problems for us as they persist for weeks as a weak layer. In addition, we can never be sure of where they formed, and if they were destroyed, prior or during the big storm we all desire.

Weather Forecast and Avalanche Outlook

High pressure shifts eastward over western Montana and will persist through Friday. A Pacific weather system approaches the region Saturday, which will push a significant surge of moisture and energy across north central Idaho and western Montana late Saturday night and Sunday. The best moisture enhancement will be the Clearwater, Bitterroot and Mission mountains north to Glacier Park. Winds start out from the south and east but turn westerly and increase at higher elevations Saturday.

Please take the time to fill out our survey. This is your opportunity to let us know what you think the strengths and weaknesses of our program are and where we need to go in the future. Your comments make a difference. We wouldn’t have an avalanche center here if it wasn’t for your written comments a few years ago and we wouldn’t be issuing advisories 2 days each week and as needed if it wasn’t for your comments, participation and financial support of the West Central Montana Avalanche Foundation. THANKS FOR YOUR CONTINUED SUPPORT!

If you get out and see avalanche activity or want to send us quick snow observations, send us a note at [email protected] or call us at 406-530-9766. 530-9SNO.


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.