Mar 22, 2016 @ 6:34 am

The current avalanche danger is LOW for the west central Montana backcountry. Human triggered avalanches are still possible in isolated terrain and conditions may change rapidly throughout the day as a strong system of snow moves into the area. Carefully assess how the new snow is affecting the snowpack and don’t be surprised if the danger climbs to moderate by the afternoon. 

Good morning,  this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for Tuesday, March 22nd, 2016. 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

Snow is slowly moving into the area and a trace to 2 inches of snow has been recorded so far this morning. Currently mountain temperatures are hovering around freezing and winds are light and gusting to the teens from the ESE- S as the storm pushes into the region. Snow is expected to continue and intensify through midday and snow levels will drop throughout the morning.

Tim and I rode from Lolo Pass to Granite Pass yesterday and found wet saturated snow. The snowpack is moving towards being isothermal and mostly wet rounded and polycrystals were seen yesterday. We found loose wet slides to be the primary concern yesterday and loose snow will continue to be the primary concern today in the form of loose wet in areas that are receiving still relatively warm or receiving significant solar radiation and loose dry in areas that are accumulating new cold snow.

The new snow should bond fairly well to the old warm snow surface but as more snow falls keep an eye on how the storm slab bonds. If snow totals are high enough and there is a significant new load of SWE give the snow time to adjust to the new load. With temperatures hovering right around freezing as the snow is starting to fall areas may have had the snow surface freeze and now the new storm snow will be accumulating on a good bed surface. Storm slabs will not be apparent first thing this morning but will potentially develop later in the day so plan accordingly when choosing when and where to recreate today. 

Weather and Avalanche Outlook

Currently light snow is falling in the mountains of west central Montana and more is expected through noon. Above 6,000ft about 6+ inches is predicted in the forecast and snow totals will be greater towards the northern half of the advisory area. Winds will likely increase and shift to the west as the system moves into the region. The new snow will increase the avalanche danger in areas where enough snow has fallen to overload the interface or other weak layers in the snow pack.

Ski and ride safe, the next advisory will be issued on Thursday.


Problem 1 - Loose Dry and Loose Wet

  • TYPE


    Loose Dry

    Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose-Dry Avalanches,they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose-wet avalanches can trigger slab avalanches that break into deeper snow layers.

  • SIZE


    1 (Small)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

Loose Snow avalanches will be the primary concern today on slopes steeper than 35 degrees.

Problem 2 - Storm Slabs

  • TYPE


    Storm Slabs

    Release of a soft cohesive layer (a slab) of new snow which breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-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


    1 (Small)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

The snow is falling right-side up but storm slabs may become reactive if significant amounts of SWE are recorded or in areas where the snow is accumulating on a crust or slick bed surface.


  • Danger Trend


    Increasing Danger

  • Area Forecast


More snow is expected through the morning hours and snow line will continue to drop through the day. Mountain accumulation are expected to be around 6+ inches above 6,000 feet.

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.