Feb 7, 2011 @ 6:53 am

February 7, 2011 Avalanche Advisory

Hello! This is Steve Karkanen with the West Central Montana Avalanche Center’s backcountry avalanche advisory for Monday, February 7, 2011.

Current Avalanche Danger

On all slopes above 5000 feet, the avalanche danger is MODERATE. Natural avalanches are unlikely, human-triggered avalanche are possible. There are heightened avalanche conditions on some terrain features.

Areas of concern are steep slopes recently wind-loaded where sensitive wind-slabs have formed or where it is possible to trigger large sluffs. While these loose snow avalanches can usually be managed with careful skiing and riding technique it is possible to be knocked down and carried into trees or other terrain traps if you’re taken by surprise.

All other slopes including areas below 5000 feet now have a LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Be aware of unstable snow in isolated areas that have been influenced by wind and terrain.

Weather and Snowpack Analysis

Once again the primary avalanche concern is wind slab development in areas exposed to high W-NW winds the past few days. Most locations received just a few inches of snow Friday with W-NW winds 25-30 mph on the higher exposed ridge-tops.

This wind scoured W-NW and even some N aspects and stiff wind slabs have formed on leeward slopes in many areas. These wind slabs can be very touchy and can take you for a nasty ride if you get caught in one. These can be found mostly above 7000 feet on E-S aspects. This video is a good example of what we found in an isolated pocket in the Rattlesnake Sunday.

Observers in the Saddle Mountain, Lolo Pass, Rattlesnake and in the N Fk of Placid Creek near Seeley Lake were reporting mostly stable snow conditions. A heavy load of new snow will likely overload the cold dry snow at the surface as well as the wind-slabs that formed at higher elevations.

We received a report of natural avalanche activity in the southern Swans on both south and north aspects but it is unknown whether these are loose snow or slab avalanches.

SNOTEL sites throughout the advisory area are reporting 2-3” of new snow this morning and it is currently snowing.

Weather Forecast and Avalanche Outlook

A cold upper level trough will move over western Montana Monday delivering snow while an Arctic air mass spills over the continental divide bringing strong easterly winds and wind-blown snow.

Snow begins to taper off Monday night but the combination of very cold air and wind will create dangerous wind chill values. Tuesday through Wednesday a northerly flow aloft will maintain the cool influx from Canada but the pressure gradient will relax allowing winds to diminish. Some moisture is expected to make it’s way over the top of this ridge with the potential for light accumulation of snow.

Temperatures will begin to moderate but remain below the seasonal average.

Expect avalanche conditions to increase to CONSIDERABLE on steep terrain as we continue to receive new snow and wind.

Dudley issues the next advisory on Friday February 11, 2011.

Upcoming Events:

Avalanche Film and Raffle at the ON Store

The ON Store is hosting a fundraiser for the West Central Montana Avalanche Foundation at their location in the Southgate Mall on Monday February 7 from 6-9PM.

This will be an informative and fun event with a demo of GO PRO video cameras by a company rep and a short talk by Steve Karkanen from the Avalanche Center who will be showing an excellent avalanche film called The Fine Line. Ski and riding films will be showing throughout the store until closing.

There will be a raffle of a Go Pro helmet camera and accessories and a DaKine backpack.

Raffle tickets are $5 and you must be present in the store to win.

All proceeds from the raffle will be donated to the Avalanche Foundation. In addition, the ON Store is generously donating 1% of the days sales to the Foundation.

This event starts at 6PM with the Go Pro rep followed by the avalanche film at 7PM then the raffle after the film around 8:15PM. Other films will run until closing at 9PM.

There is no charge for entry but we encourage you to buy as many raffle tickets as you can afford!

If you’re thinking about a new laptop, video camera or any electronic gear, Monday would be a great day to make that purchase. Hope to see you there!

There is still room in the Level 2 scheduled for February 15-18 so please sign up at the American Avalanche Institute web site.


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.