Nov 30, 2007 @ 12:00 am

Early Season Update for December 1, 2007

Hi! This is Steve Karkanen at the West Central Montana Avalanche Center with an early season avalanche information update for November 30, 2007.

West Central Montana has been under the influence of a fairly wet but very cool air mass that continues to produce snow showers over the area. Average temperatures have been in the low 20’s at most mountain locations and the SNOTEL sites have picked up a few more inches of snow since Thanksgiving.

While most mountain locations don’t yet have enough snow to be a problem, there are places where you can easily trigger an early season avalanche. These places tend to be leeward open slopes steeper than 30 degrees where wind blown snow is deep enough to cover anchors. 8000′ wind speeds have been in the 30 mph+ range on several occasions this past week which is certain to load the leeward slopes. Even a small avalanche on a small slope can have severe consequences so travel with a partner, never expose more than 1 person at a time in avalanche terrain and be prepared to take care of yourself if things don’t go as planned. We’ve been getting some reports from backcountry skiers who are noticing faceted snow at the ground and surface hoar crystals in some areas of the Southern Bitterroot. These spotty weaknesses may be a problem if the snow is deep enough, the slope steep enough and if someone blindly jumps onto one of these weaker areas.

The Missoula Office of the National Weather Service is forecasting the possibility of significant mountain snow by Saturday night as the upper level flow transitions back to a more southwesterly pattern. This may allow warm pacific moisture to stream over the colder air at the surface causing significant snow. Weather models suggest continued moisture and warming temperatures through midweek. Significant snowfall at warmer temperatures may cause an unstable situation (heavier wetter snow deposited on drier lighter snow) until the snowpack has a chance to adjust to the new load. Pay close attention to changes in the weather during the 1st few days of December.

We begin issuing regular weekend advisories on December 14th. If you are out and see avalanche activity or just want to send us some information about what you see out there, please send us a note from our website. We are working with limited information right now so any observations we receive from the field are very helpful. Local ski areas are in the early stages of opening and may or may not allow you uphill travel on their slopes. The best policy is to ask and treat any unopened ski area as if it were the backcountry.

We have scheduled several avalanche awareness sessions this winter and are available to give avalanche safety presentations to groups or businesses in Western Montana. Many of these sessions are posted on our Education and Events page. We are also scheduling avalanche awareness classes for grades 5-12. Call us at 406-329-3752 for further information.


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.