MissoulaAvalanche.org

Avalanche Information for West Central Montana

February 3, 2012 Avalanche Advisory

Current Danger Rating is MODERATE

In the west central Montana backcountry above 6000 feet there is MODERATE avalanche danger on slopes steeper than 35 degrees.  There is LOW avalanche danger on all other slopes above and below 6000 feet.

Hello backcountry skiers and riders!  This is Steve Karkanen with the West Central Montana Avalanche Center’s avalanche advisory for Friday February 3, 2012.

Moderate avalanche danger means there is heightened avalanche conditions on specific terrain features where natural avalanches are unlikely but human triggered avalanches still possible. Small avalanches are possible in specific areas and large avalanches in isolated areas.

Low avalanche danger never means NO avalanche danger. Areas below 6000 feet have either had an opportunity to settle out and adjust to the weight of the most recent snowfalls or simply don’t have enough snow to be a problem.

Avalanche Accident

An avalanche accident claimed the life of a backcountry skier Wednesday in the Jewel Basin located in the northern Swan Range northeast of Bigfork, MT.  Preliminary reports state that a large cornice collapsed under the victim then triggered a large avalanche as it rolled dowslope.  Avalanche specialists with Glacier Country Avalanche Center are investigating the accident and will post details on their website glacieravalanche.org as they complete their investigation.  Our thoughts and prayers are with the family and friends of the victim.

Weather and Snowpack Analysis

SNOTEL sites throughout the advisory area picked up about an inch of SWE or about 10 inches of snow since Sunday.  Winds were primarily from the SW early in the week but were out of the N-NW Thursday.  This newer snow is heavy and dense so was able to form wind slabs in many ridgetop locations.

This morning the sky is clear and mountain temperatures are in the teens and low 20′s.

Warmer temperatures and rain in many areas up to 6000 feet have helped further settle our snowpack during the week.  Observers near Lost Trail, Hoodoo Meadows, Lookout Pass and in the Rattlesnake all report mostly stable snow conditions with the earlier weaknesses continuing to gain strength.  Skiing and riding conditions have been excellent above the rain line.

The higher terrain in the southern Swan has a lot of variability and the guys at Yurt Ski recommend that skiers and riders pay close attention and dig around a bit before committing to anything steep.

Our northern Mountains above 8000 feet have serious depth hoar 50-70 cm thick at the ground.  The snowpack above this faceted layer is very strong and it doesn’t fail under conventional stability testing but it is something to keep in mind when it snows heavily again or warms up quickly.  A slab avalanche involving the upper newest snow could be enough weight to trigger a much deeper catastrophic slide.  The probability is low of triggering an avalanche involving this layer but the consequences would be severe.

Weather Forecast and Avalanche Outlook

The Missoula Office of the National Weather Service is forecasting a ridge of high pressure to dominate our weather for the next several days.  Mountain temperatures will gradually warm into the 30′s while valley locations remain cold and foggy.  I expect the avalanche conditions to continue to slowly improve during this episode however it will be important to pay close attention to the sun exposed slopes and watch for wet snow avalanches during the peak of afternoon heating.

Clear dry conditions are great for fair weather skiers and riders but not so great for future snow stability.  Expect to see significant surface hoar development the next few days and remember where you see before it gets buried.  This will be our next big concern for stability when it starts snowing again.

Fund Raising Event

Please join us tonight for the premiere showing of the latest Warren Miller film “Like There’s No Tomorrow” at the Wilma Theater.  Doors open at 7PM and the show starts at 8PM.  A portion of all proceeds will benefit our friends group the West Central Montana  Avalanche Foundation.  There will also be a raffle drawing during intermission with several very nice gear, clothing and lift tickets to local resorts being given away.  It’s worth the price of admission just to get a chance to buy raffle tickets for this gear!

Let us know what you see out there.  Your information helps us better inform everyone about avalanche safety.  The life you save may be your own!

I will post the next advisory on Monday, February 5.  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 you can use the information we provide to help you make more informed decisions regarding travel in avalanche terrain for the next few days.

Our advisory area includes the Bitterroot Mountains from Lost Trail Pass North to Hoodoo Pass, the Rattlesnake Mountains and the Southern Swan and Mission Mountains near Seeley Lake. Avalanche information for the Lookout Pass/St. Regis Basin is available from the Idaho Panhandle Avalanche Center.