Dec 13, 2013 @ 6:48 am

December 13, 2013 Avalanche Advisory

Today’s avalanche danger in the west central Montana backcountry is MODERATE  on wind loaded terrain steeper than 35 degrees above 6000 feet.   There are isolated pockets on north to east facing steep open slopes and gullies where it may be possible to trigger one of these wind slabs.

Below 6000 feet the avalanche danger is LOW.

Good morning!  This is Steve Karkanen at the West Central Montana Avalanche Center with the avalanche advisory for Friday December 13, 2013. This avalanche danger rating expires at midnight on December 13th, 2013.

Weather and Snowpack Analysis

Our observers visited backcountry locations near Lost Trail Pass, Lolo Pass, Hoodoo Pass and the Rattlesnake yesterday.  Everyone was out looking for weak faceted snow but came back with evidence that the overall snowpack has adjusted well to the most recent snowfall.

There are a couple of avalanche problems that need to be checked out prior to committing to anything steep.

The mountains north of Missoula received 18 to 28 inches of snowfall this past Tuesday. SNOTEL sites in the Bitterroot recorded less snow, but at elevations above 8000 feet high winds have been moving much of this storm snow onto east and northeast aspects.

None of our observers saw evidence of recent avalanche activity but these wind slabs  could be an issue on leeward terrain at the higher elevations.

This past Tuesday’s storm snow is bonding well to the older snow surface.

The overall snowpack has had time to adjust to this load and is showing signs of continued strengthening through settlement.  Stability testing indicated low energy failures at the interface of the old snow surface and deeper into the snowpack at the ice crust that formed during the warm weather in November.

We’ve posted 4 snow pit profiles from the above locations available for viewing here.


Weather Forecast and Avalanche Outlook

The backcountry weather forecast from NOAA Missoula Weather Service reports warmer conditions Saturday through Monday with only light amounts of snow for the period.

I expect that conditions should improve during the warmer temperatures over the weekend.


Additional Safety Information

The local ski resorts are in early season mode and not yet fully open.  When closed, the terrain inside resort boundaries is considered backcountry with no avalanche control and no rescue services.  Ski areas with snow making equipment may have power and water lines exposed on or just under the snow surface that can be easily cut by a ski edge. Grooming equipment may be operating at any time of day or night.  If you plan to hike/skin the terrain inside a ski area permit boundary please respect private property and understand that you are responsible for your own welfare.

If you are unsure of a resort’s policy, the time honored Montana tradition is to ask for permission.


Advisory Area Map Revised

We have a more clearly defined boundary map available for review here.  The areas our observer group and avalanche forecasters routinely visit are the Lost Trail, Lolo and Hoodoo Pass areas in the Bitterroot mountains, the Rattlesnake mountains and southern Swan and Missions near Seeley Lake.  There are large areas in between that we may or may not frequent therefore we rely on information from backcountry skiers and snowmobilers who visit these areas.  This information is vital to us and help us produce a better product.

If you get out and see weather and snow conditions that you’d like to share, you can easily submit an observation here or simple send us a quick email to [email protected].  Your information could save a life!

The next avalanche advisory will be issued by Dudley Improta on Tuesday, December 17, 2013.  Have a safe weekend!


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.