Feb 8, 2010 @ 12:00 am

February 8, 2010 Avalanche Advisory

Posted 0600 on February 8, 2010.

Hello! This is Steve Karkanen at the West Central Montana Avalanche Center with backcountry avalanche information for Monday, February 8, 2010.

Current Avalanche Danger

On all slopes steeper than 35 degrees and on all aspects above 6000 feet, the avalanche danger is MODERATE. Natural avalanches are unlikely, human triggered avalanches are possible. On all other terrain above and below 6000 feet, the avalanche danger is LOW, natural and human triggered avalanches are unlikely.

During periods of rapid warming the avalanche danger can quickly raise to CONSIDERABLE, natural avalanches are possible and human triggered avalanches likely. Many wet snow point release avalanches occur during periods when the sun bakes a slope for a few minutes. While these smaller avalanches by themselves do not present much of a hazard, it is possible the rapid load to a weak snow structure can result in these slides stepping down to the weak facets at the ground.

Weather and Snowpack Analysis

Since Friday, all the SNOTEL sites recorded minimal amounts of precipitation. Afternoon temperatures have been in the 30’s each day and the wind has not been a factor this week. Shaded aspects are still skiing well and riding conditions are very good where the snow is deep enough.

Weak faceted crystals are present in the upper 20cm of the snowpack that fail during stability testing but this currently is not much of an avalanche problem. A heavy load of new snow will be of concern unless we see a couple of melt-freeze cycles that affect this layer. Afternoon temperatures have been above freezing at most mountain locations and this trend is expected to remain with us for a few more days.

Weather Forecast and Avalanche Outlook

Two comments sum up our conditions concisely. The first is from a weather forecaster who said; “High pressure will dominate through Thursday, what else would you expect in this El Nino winter?”

The other comment is from Dudley referring to a sun crust, which is the weakest feature in the current snowpack with 5-10cm of near-surface facets under the crust. He states; “the crust breaks with lots of energy but is just not very deep and does not constitute a hazard except for the breakable crust itself”.

So now, we wait for the next big change in weather.

Everything we see in the backcountry right now is telling us we have a mostly stable condition but that does not give us the green light to abandon safe travel preparations and procedures.

We are seeing many examples of unsafe route finding in the Rattlesnake recently. We think most people are choosing these routes because of the low hazard right now but remember, people tend to follow the path of least resistance when skinning. Under these conditions that is proving to be across steep open slopes, over slope convexities and through areas where people are exposed for a longer period than necessary in places where we have seen avalanches triggered over the years. Yeah, you can get away with it under low hazard conditions but please understand that a skin track set through a starting zone or an area exposed to avalanche terrain will be followed by less knowledgeable individuals during high hazard conditions.

We live and die by our habits. Stick with proven safe travel protocol and avoid taking shortcuts through hazardous terrain. It’s one thing to expose yourself to avalanche terrain for a couple of minutes when skiing, quite another to expose yourself, your partners and those who follow your track for 20 minutes or so while you trudge back up the hill for another run.

It is still possible to trigger an avalanche on some terrain features. Many places are still holding weak faceted snow especially on shallow rocky slopes. Pay particular attention to wind loaded terrain even after minor snowfall amounts. Always carry and know how to use a transceiver, probe and shovel and always travel with only one person exposed to hazardous terrain.

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.