Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Sunday, April 14th at 7:00 a.m. This is our 130th and final forecast for the season. Thank you to the readers of the forecast, everyone that sent in observations, took an avalanche class, or donated money, time or gear. Our success is directly related to support from our community and the Forest Service. Thank you for another great season.
We will issue conditions updates on Mondays and Fridays through April. This forecast does not apply to operating ski areas.
This morning temperatures are low 30s to mid-40s F with high 20s to mid-30s F near Cooke City. Wind is out of the south-southwest at 5-10 mph with gusts of 15-25 mph. There is no new snow. Today, under mostly sunny skies, temperatures will reach high 40s to low 60s F, and wind will be 5-10 mph from various directions. Clouds will increase tonight, and in some places skies might cloud up this afternoon. There is a chance for rain tonight and tomorrow, turning to chances for snow late tomorrow into Tuesday.
Temperatures remained above freezing for the third night in a row. Today will be another day of clear skies and above freezing temperatures which makes wet snow avalanches a likely hazard you will encounter on and below steep slopes. In the Bridger Range temperatures are what I would call “hot” with lows in the 40s F at all elevations this morning.
Loose wet avalanches ran naturally over the last few days. Today you can expect similar slides to run naturally and be easy to trigger on steep slopes (photos from Bridgers). The snowpack will continue to melt today, and without freezing overnight, slides have the potential to be larger with a possibility of bigger destructive wet slabs. In the Bridger Range the avalanche danger is CONSIDERABLE this morning, and it will quickly rise to HIGH. Travel in avalanche terrain is not recommended.
Where temperatures were closer to freezing, clear skies overnight probably helped freeze the snow surface at least a little. In some regards, the snowpack held up surprisingly well during the last few days of heat, but today could be the day it falls apart. Wet snow avalanches will quickly become a concern when the snow surface starts to melt with today’s sun and warm temperatures.
Stay diligent with careful snowpack assessment and cautious route finding. When the snow surface gets wet and unsupportable more than a few inches deep, wet avalanches will be possible and will quickly become more likely through the late morning and middle of the day. Plan to be off and out from underneath steep slopes before the snow becomes too wet, and make sure you have safe options for your egress out of the mountains.
Cornices along ridgelines have been weakening with the warm temperatures and breaking naturally, and a skier triggered one on the Sphinx on Thursday (Sphinx photo). These can be dangerous on their own, and they can trigger larger slab avalanches (as this photo from Iceberg Peak demonstrates). A falling cornice could trigger an avalanche on the deeper weak layers we haven’t seen activity on in weeks. Give cornices a wide berth as you travel along ridgelines and minimize time spent on slopes below.
On shady slopes where the snowpack has stayed dry you might still be able to trigger a wind slab or an avalanche on weak layers in the upper couple feet of the snowpack. Dig a quick snowpit and do a stability test to make sure you don’t get surprised.
The avalanche danger is MODERATE this morning and will quickly rise to CONSIDERABLE as the day heats up.
This is our last daily forecast of the season. We will continue to issue conditions updates on Mondays and Fridays and as needed through the rest of April.
If you get out please submit an observation. 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 by email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Hyalite Road Closure: Hyalite road is closed to ALL MOTORIZED VEHICLES until the morning of May 16. This is a regular annual road closure to reduce road damage during the spring thaw. Bicycle and foot traffic are allowed. Contact the Bozeman FS Ranger District for more info.
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.
On Tuesday, April 9th, Doug Chabot wrote his final avalanche forecast for the Gallatin National Forest Avalanche Center. Doug, thank you for your friendship, mentorship and 29 years of service to Southwest Montana’s community. Congratulations on your fast approaching retirement!