Posted:
Mar 8, 2018 @ 6:07 am

The current avalanche danger is LOW for the west central Montana backcountry. Low danger does not mean no Avalanche danger. Use safe travel protocols, only exposing one person to a slope at a time. Look for loose wet avalanches to be the primary concern with warming temperatures below 6000 feet.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for March 08, 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 25 F to 32 F in the region. In the Bitterroot winds are 11mph with gusts of 17 mph out of the SW. In the northern part of the advisory area, winds are reading 9 mph with gusts of 20 mph out of the NW. The forecast area received no new snow in the last 24 hours.

Logan and I were in the Rattlesnake yesterday. Tim and Greg went to Mt. Fuji near Lolo Pass. We all found our snowpack to be relatively stable. The primary avalanche problem was loose wet avalanches on southern exposed slopes. We were not able to get any propagations in our pit tests.

The primary avalanche problem is loose wet avalanches on slopes below 6000 feet. Snotels showed that all sites froze overnight and temperatures are rising. Rollerballs will be signs of surface instabilities. If you see pinwheels, it is time to change aspects or get to higher elevations.

Overall the snowpack is well consolidated. Cornices are big right now give them a wide berth. With warming temperatures, these large cornices are weakening. Dig a pit 3 feet down before committing to any steep terrain. Use safe travel protocols, only exposing one person to a slope at a time.

Avalanche and Weather Outlook

Later today a warm wet system will move into the region. See the forecast here. This new snow will fall on a variety of old snow surfaces from sun crusts to surface hoar. Use small test slopes to see how the new snow is bonding to old snow surfaces. With the addition of fresh snow or rain below 5000 feet look for the avalanche danger to increase. Pay attention to weather changes that can change the avalanche danger such as wind and additional loading from snow.

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 - Loose Wet

  • TYPE

    loose-wet

    Loose Wet

    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

    2-3

    1 (Small)

    The potential size of avalanche resulting from this problem.

  • LIKELIHOOD

    Likelihood-2

    Unlikely/Possible

    The likelihood of an avalanche resulting from this problem.

  • IMAGE

Snotels showed that all sites froze over night and temperatures are rising. Rollerballs will be signs of surface instabilities. If you see pinwheels, it is time to change aspects or get to higher elevations.

VIDEO

Observations Rattlesnake 03/07/2018

GALLERY

Rattlesnake Study Plot-07-Mar
Rattlesnake Study Plot-07-Mar
IMG_0752
IMG_0752
IMG_0750
IMG_0750
IMG_0751
IMG_0751
Loose Debris 3/7/18
Loose Debris 3/7/18
Roller Balls
Roller Balls
Surface Hoar
Surface Hoar

Observations 03/07/2018

FORECAST & OUTLOOK

Later today a warm wet system will move into the region. See the forecast here. This new snow will fall on a variety of old snow surfaces from sun crusts to surface hoar. Use small test slopes to see how the fresh snow is bonding to old snow surfaces. With the addition of new snow or rain below 5000 feet look for the avalanche danger to increase. Pay attention to weather changes that can change the avalanche danger such as wind and additional loading from snow.

 

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.