Feb 7, 2011 @ 3:24 pm

Special Update for February 7, 2011

Hello! This is Steve Karkanen with a special update to the West Central Montana Avalanche Center’s backcountry avalanche advisory for Monday, February 7, 2011. This update was issued at 1530 on February 7, 2011.

Current Avalanche Danger

On wind-loaded slopes steeper than 30 degrees, the avalanche danger is HIGH. Natural avalanches are likely and human-triggered avalanches are very likely. Large avalanches are possible wherever wind slabs have formed especially at the higher elevations above 5000 feet..

All other slopes above 5000 feet and steeper than 30 degrees have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely.

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.

On all slopes below 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.

Weather and Snowpack Analysis

This special update to the avalanche danger is based on the heavy load of new snow and high winds received across the advisory area today.

This heavy new snow is being deposited on a layer of weak layer of cold light snow and in some areas, faceted snow that formed during the cold temperatures last week.

SNOTEL sites throughout the advisory area have picked up an inch or more of Snow Water Equivalent (SWE) the past few hours and it is expected to keep snowing through the evening. High W-NW winds are present at the higher elevations and easily moving snow around. The Point Six RAWS station recorded a wind gust of 62 MPH this morning before it shut down.

We received a report of remotely triggered avalanche activity in the southern Swans on both south and north aspects. These slab avalanches propagated over a long distance about a foot deep. The southern Swans picked up about a foot of new snow this past weekend prior to the current storm.

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 remain HIGH for the next several hours until the snowpack has a chance to adjust to this new load.

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

Upcoming Events:

POSTPONED  Avalanche Film and Raffle at the ON Store  POSTPONED

When was the last time you heard that a ski film had to be cancelled due to snow?  Because of heavy new snow and emergency travel only, the On Store elected to postpone Monday night’s showing of The Fine Line and the raffle until a later date.  We will post the new date here once we know it.

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!


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.