Jan 9, 2012 @ 6:41 am

January 9, 2012 Avalanche Advisory

There is a MODERATE avalanche danger in the west central Montana backcountry. Evaluate snow and terrain carefully; identify features of concern. There are pockets of CONSIDERABLE avalanche danger found on previously wind-loaded slopes steeper than 35 degrees throughout our advisory area. Careful snowpack evaluation, cautious route-finding and conservative decision making essential.

The avalanche danger below the elevation of 5000 feet is LOW.

Good Morning! This is Tim Laroche at the West Central Montana Avalanche Center with your backcountry avalanche advisory for Monday, January 9th, 2012.

Weather and Snowpack Analysis

Most advisory area locations picked up 1-2 inches of new snow over the weekend. The exception was the southern Mission and Swan mountains where snotel sites reported 5 inches of new snow. Temperatures are ranging in the mid to upper twenties and the winds are light out of the southwest this morning under clear skies.

Steve and I toured around the Saddle Mountain area in the southern Bitterroots yesterday to have a look at what we think is the weakest snowpack in our advisory area. We found a variable snowpack that is showing signs of strengthening, but is still harboring the persistent weak layers of buried surface hoar with weak faceted snow below. These weaknesses are now buried 1-3 feet deep and there is a dense slab sitting in the upper part of the snowpack. We are getting these weak layers to fail in stability tests in some locations, but not others. These same conditions are being reported in other destinations within our advisory area (check out our public observations page). This is what makes things tricky out there right now.

The most likely places you will be able to trigger a slide are just off upper elevation ridgelines that have been wind-loaded and shallow areas within the snowpack on steep, rocky slopes. We received this photo of a skier triggered slide in the Gash Point area this past weekend. Given the variability we are experiencing in our snowpack, this is a good time to be conservative in your decision making in the backcountry.

The snowpack is settling and stability tests are showing some improvement. There are places where you will find soft snow to ski and ride in. This is a good time to enjoy the soft snow on the shaded aspects of lower angle or treed terrain without committing yourself to steep open avalanche prone areas where it will be possible to trigger a slab.


Weather Forecast and Avalanche Outlook

A weather system will drop out of Canada tonight and produce snow amounts in the 5-8 inch range at upper elevations through Tuesday. Winds will be moderate mainly out of the west and northwest while temperatures will be in the 20’s. We will then slide back into a high pressure scenario through the end of the week.

I expect the avalanche danger to increase with the new snow, especially on wind-loaded slopes.

Steve will issue the next advisory on Friday, January 13th.

Thank you to all of you that have taken the time to send us your observations. If you get out and have the time to send us some information about what you are seeing, please use our “submit observation” link on our website or send us a quick note at [email protected]. This information is invaluable to us and in turn comes back to you in the form of a better forecast.

Mark your calendars now for our upcoming Pint Night at the north side Kettle House on January 18th. 5-8pm.




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.