Good morning. This is Alex Marienthal with avalanche and weather information from the Gallatin National Forest Avalanche Center on Sunday, December 3rd, at 7:20 a.m. This information is sponsored by Uphill Pursuits and the Cooke City Super 8/Bearclaw Bob’s. We will update this information as conditions change.
Since snowfall began on Friday the mountains received 12-14” of low density snow near Cooke City, Big Sky, West Yellowstone and Island Park, and 3-6” in the Bridger Range and Hyalite. Wind has been out of the west at 10-25 mph with gusts of 40-60 mph. Temperatures are single digits to teens F this morning. Today, temperatures will reach mid-20s to low-30s F, wind will be westerly and increase this afternoon to 25 mph with gusts of 40-50 mph.
Snow showers will continue through tomorrow and will favor the mountains near Cooke City with 5-8”, and 1-3” elsewhere. Tuesday through Wednesday, daytime temperatures will reach mid-30s to low 40s F under partly sunny skies. Late Wednesday into Thursday temperatures will return to 20s to low 30s F with snow possible through next weekend.
Prior to this weekend’s snow the mountains held a mix of dry slopes and slopes with up to 12-20” of old snow. During our recent dry spell that old snow became faceted and weak. I witnessed this in the northern Madison Range on Thursday (video), and Ian saw it a couple weeks ago on Sawtelle Peak (observation). Yesterday, skiers at Bridger saw 3” inches of wind-drifted new snow easily cracked on top of the old, weak snow (observation and photo), and Doug noted similar potential for avalanches while climbing in Hyalite (observation).
Near West Yellowstone and Cooke City got 12-14” of snow equal to 1.0” of snow water equivalent (SWE). This will create dangerous avalanche conditions, especially as more snow falls over the next 24 hours and where strong winds drift this snow into thicker slabs.
Carefully assess the stability of recent snow prior to riding or crossing below avalanche terrain. Avoid steep slopes where more snow fell, where new snow is drifted into thicker slabs, and if you see recent avalanches or cracking and collapsing in the new snow. Carry your avalanche rescue gear (beacon, shovel, probe) and make sure your and your partner's gear and skills are in working order.
Over a foot of new snow equal to 1.0” of snow water equivalent (SWE) creates dangerous avalanche conditions, especially where strong winds drift this snow into thicker slabs. Carefully assess the stability of recent snow prior to riding or crossing below avalanche terrain. Avoid steep slopes where more snow fell, where new snow is drifted into thicker slabs, and if you see recent avalanches or cracking and collapsing in the new snow. Carry your avalanche rescue gear (Beacon, shovel, probe) and make sure your and your partner's gear and skills are in working order.
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.
Monday, December 4th, 6:30 p.m., FREE Avalanche Awareness at MAP Brewing
Tuesday, December 5th, 6:00 p.m., Free Avalanche Awareness + Beacon Demo Clyde Park Community Hall, hosted by the Big Sky SnowRiders
Tuesday, December 9th, 9:00 a.m. to 3:00 p.m., West Yellowstone Motorized Avalanche Fundamentals, Pre-registration and more information HERE.
We offer Avalanche Fundamentals with Field Session courses targeted towards non-motorized users in December and January and one geared towards motorized users in January. Sign up early before they fill up.
Loss in the Outdoors, is a support group for those who have been affected by grief and loss related to outdoor pursuits. Check out the link for more information.
We travel with a lot of electronics that could interfere with our avalanche transceiver, both as a victim and as a rescuer. Check out our article on Electronic Warfare to learn what to do.