Posted:
Mar 6, 2018 @ 6:17 am

The current avalanche danger is MODERATE in the west central Montana backcountry. Human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for March 06, 2018.  This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 15 F to 21 F in the region. In the Bitterroot winds are 5 mph with gusts of 11 mph out of the SSW.  In the northern part of the advisory area, winds are reading 8 mph with gusts of 15 mph out of the NNW. The forecast area received 1 to 6 inches of new snow in the last 24 hours.

Logan and I took the sleds to the Brushy Fork in the central Bitterroot yesterday. Tim went to the Rattlesnake. We all found wind loaded terrain to be the primary avalanche problem. Logan and I experienced intense snow banding yesterday. There are weak layers in our snowpack, but they were unreactive in our pit tests. We got several public observations from the weekend of similar problems. Overall our snowpack is relatively stable.

The primary avalanche problem is wind slabs. Identify wind loaded terrain. Look for rounded pillows of snow near ridgelines and on cross-loaded slopes. Recognize signs of instability such as cracking in the surface snow. It is possible to cause a slab avalanche on wind loaded terrain today.

Overall our snowpack is relatively stable. Identify wind loaded terrain. Dig a pit 3 feet deep before committing to any steep terrain(>35 degrees). Use small test slopes to see how the new snow is bonding to old snow surfaces. Cornices are very large this time of year and unpredictable in failure, give them a wide berth. Loose snow avalanches should not be a problem unless they knock you down and take you into terrain trap.

Avalanche and Weather Outlook

Light snow banding today. See the forecast here. Look for the avalanche danger to stay the same with these light accumulations. I will issue the advisory on Thursday, March 08.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory.

Ski and ride safe.

 

 

READ FULL ADVISORY  

Problem 1 - Wind Slabs

  • TYPE

    wind-slabs

    Wind Slabs

    Release of a cohesive layer of snow (a slab) formed by the wind.  Wind typically erodes snow from the upwind sides of terrain features and deposits snow on the downwind side.  Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

  • SIZE

    3-4

    1-2 (Small-Large)

    The potential size of avalanche resulting from this problem.

  • LIKELIHOOD

    Likelihood-3

    Possible

    The likelihood of an avalanche resulting from this problem.

  • IMAGE

Identify wind loaded terrain. Look for rounded pillows of snow near ridgelines and on cross-loaded slopes. Recognize signs of instability such as cracking in the surface snow. It is possible to cause a slab avalanche on wind loaded terrain today.

VIDEO

Brushy Fork 03/05/2018

Observations 03/05/2018

FORECAST & OUTLOOK

Light snow banding today. See the forecast here. Look for the avalanche danger to stay the same with these light accumulations. I will issue the advisory on Thursday, March 08.

 

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.