Mar 21, 2008 @ 7:00 am

March 21, 2008 Avalanche Advisory

Weekend Avalanche Advisory
Posted March 21st at 0700

Hello! This is Steve Karkanen at the West Central Montana Avalanche Center with the weekend avalanche advisory for March 21st – 23rd, 2008. The avalanche danger rating expires at midnight March 21st. This report is based on field observations and data collected on Thursday and describes conditions seen at that time. This advisory is the sole responsibility of the Forest Service and does not apply to operating ski areas.

Weather and Snowpack Analysis

Mountain locations above 5000′ continue to receive bursts of accumulating snowfall. While these short-lived impulses of moisture are not big precipitation producers they have slowly added more snow to an already above normal snowpack. The snow we’ve been seeing is of a higher density and quickly settles once on the ground. This type of snowfall accumulation bodes well for stability as the snowpack has plenty of time to adjust to the new load and gain strength. All observers are reporting mostly stable conditions with high stability test scores and good skiing and riding conditions. 8000′ winds have been moving snow at the ridge tops so any leeward aspects must be treated with caution as wind slabs were forming on these slopes.

Today’s Avalanche Danger

Above 5000′ on slopes steeper than 35 degrees the avalanche danger is MODERATE. Natural avalanches are unlikely, human triggered avalanches are possible.

On all other slopes the avalanche danger is LOW. Natural avalanches are very unlikely, human triggered avalanches are unlikely. Low to moderate avalanche danger never means NO avalanche danger.

At this time of year the danger of wet snow avalanches may quickly increase to CONSIDERABLE when sun exposed slopes warm above the freezing point or whenever we receive rain at the higher elevations.

Weather Forecast and Avalanche Outlook

A Snow Advisory is in effect until 3PM for the Bitterroot and Sapphire mountains. A Pacific weather system will move into Northwest Montana Friday bringing a few inches of snow to the mountains above 2500′. High pressure will build in behind this system Friday night through Saturday night. Another system will move into the area on Sunday

Cooler weather and little snowfall will keep the avalanche danger at LOW to MODERATE conditions until the next significant snowfall or warm up.

While this is probably the most stable condition we’ve seen this winter, it is no time to let your guard down. Never expose more than 1 person at a time on a slope steep enough to slide, always carry and know how to use an avalanche transceiver, probe poles and shovel.

We received news of an avalanche fatality that occurred on March 16 in a remote area North of Orofino, ID. The preliminary information we have is that a group of friends were snowmobiling near Sheep Mountain when 3 riders were caught in a slide on an old harvest unit. 1 person was killed and 1 injured. Our thoughts are with the family and friends of the person who died in this avalanche.

The next avalanche advisory will be posted on March 28th, 2008.

If you are seeking further backcountry travel information please contact the local Forest Service Ranger District Office in the area where you wish to recreate or call us at 406-329-3752.


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.