Good morning. This is Dave Zinn with the Gallatin National Forest Avalanche Forecast on Monday, March 18th at 7:00 a.m. Today’s forecast is sponsored by the Idaho State Snowmobile Association - Avalanche Fund and Gallatin County Sheriff Search and Rescue. This forecast does not apply to operating ski areas.
Mountain temperatures are in the mid-20s to low-30s F this morning, with 5-15 mph winds from the west to the north. There is no new snow. Today will be similar to yesterday but a few degrees warmer. Temperatures will be in the mid-40s to low-50s F with 5-15 mph winds from the west to southwest. Enjoy a few more days of spring because winter is forecast to return by this weekend.
All Regions
Large avalanches breaking deep in the snowpack on persistent weak layers and wet, loose snow avalanches are possible in the mountains across the advisory area.
The likelihood of triggering an avalanche deep in the snowpack on persistent weak layers has decreased over the last week, but the consequences remain as severe as before. Ask the rider in the Taylor Fork who escaped a slide that broke 2-4 feet deep on Sunday and the skier who, less than 30 miles outside the advisory area, remotely triggered a large avalanche that snapped trees like pick-up sticks on Friday if they remain possible. You will hear a resounding yes (Taylor Fork photo and details, Lawnmower details and photos). A few days of melt-freeze cycles have not fundamentally changed the structure of the snowpack. Yesterday, a skier in Beehive Basin triggered a collapse on a small, low-angle slope with a frozen melt-freeze crust that shifted a few inches downhill (observation). Currently, accurately assessing the likelihood of a slide on the slope scale is difficult to impossible so careful terrain evaluation is our best tool. Add certainty to your day by avoiding slopes over 30 degrees (Cooke City video). Lower-angle avalanche terrain and slopes with clean runouts and without terrain traps are the best options if you choose to play the odds. Follow safe travel practices, including traveling one at a time while a partner remains in position for rescue.
The danger of wet snow avalanches will increase throughout the day as high temperatures reach the 40s and 50s F. Alex described from the Taylor Fork how a frozen melt-freeze crust is indicative of wet snow stability and a snow surface with more than a few inches of wet slushy snow indicates wet snow instability (video). Get off any steep terrain before the surface snow becomes unstable, and remember this process will happen faster in lower elevations, so ensure safe egress options. With a solid overnight freeze, these avalanches should remain relatively small, but they can pack a punch (Crown Butte wet snow avalanche, Cooke City video).
The avalanche danger is rated MODERATE.
If you venture out, please fill an observation form. It does not need to be technical. Did you see any avalanches? How much snow is on the ground? Was the wind moving snow? Simple observations are incredibly valuable. You can also contact us via email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Loss in the Outdoors is a support group for those affected by loss and grief related to outdoor pursuits. Check out the link for more information.
The Colorado Avalanche Information Center, the Avalanche Research Program at Simon Fraser University and the U.S. National Science Foundation National Center for Atmospheric Research are conducting research to examine how backcountry recreationists, including skiers, mountain snowmobilers, snowshoers and ice climbers, interpret avalanche forecast information. They aim to better understand how useful different kinds of avalanche forecast information are for trip planning. To participate, take the Colorado Avalanche Information Center survey.