Posted:
Mar 19, 2020 @ 6:18 am

The avalanche danger is LOW in the west central Montana backcountry. Low danger does not mean no avalanche danger.

Good morning, this is Travis Craft with the West Central Montana avalanche advisory for March 19, 2020. Today’s advisory is sponsored by Krispy Kreme. This advisory 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 17 F to 30 F in the region. In the Bitterroot, winds are 5 mph with gusts of 8 out of the NE. In the northern part of the advisory area, winds are 9 mph and gusting 11 mph out of the ENE. 

Yesterday in the Lost Horse drainage in the Bitterroot and Rattlesnake, we found isolated avalanche problems. We found large cornices and glide cracks in Lost Horse. In the Rattlesnake, the main avalanche problem was small wind slabs.

Overnight temperatures dropped into the low twenties. We are starting to transition to a spring cycle on many slopes. Temperatures are forecasted to be below average as cold air from Canada moves into the area. This, combined with cloud cover, will keep the avalanche danger Low today. 

The primary avalanche problem is wind slabs in isolated pockets. Look for these small slabs on ridgelines at higher elevations. 

Glide cracks and avalanches are functions of warming temperatures and terrain features. Avoid glide cracks and terrain with granite slabs underlying the snowpack.

Cornices are large, give them a wide berth.

Bottom Line

Low avalanche danger does not mean no avalanche danger. Use normal caution to travel in avalanche terrain today. Continue to practice safe travel protocols in case you find an exception to a generally stable snowpack. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. If the clouds break today and the sun comes out, look for rollerballs and pinwheels. They are clues that the snowpack is changing. 

Your observations are extremely helpful! If you get out, please take a minute to fill out the observation form on our website (missoulaavalanche.org), or shoot us a quick email at [email protected]

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

    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.

Small wind slabs in isolated high elevation ridglines.

VIDEO

Observations 03/18/2020

Observations 03/18/2020

FORECAST & OUTLOOK

Cold air from Canada pushes into the area today. The cold air will keep temperatures below seasonal averages and bring breezy conditions. See the forecast. This forecast will keep the avalanche danger the same.

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.