This is Mark Staples with the avalanche forecast for Wednesday, January 8th, at 7:00 a.m. sponsored by Klim and Cooke City Super 8/Bearclaw Bob’s. This forecast does not apply to operating ski areas.
WINDS increased this morning blowing 15-30 mph with gusts up to 40 mph from the W and NW. Temps this morning are mostly in the mid-teens F. In the Bridger Range, winds are gusty at all elevations.
The main feature driving our weather is a large ridge of high pressure over the Pacific. The jet stream is riding over this ridge and dropping down from the northwest into Montana bringing a “series of troughs, interrupted by transient ridges, through the region for the next week or so.” - NWS discussion
Today will be windy, and skies will become mostly cloudy with snowfall this afternoon. The most wind and snow will occur in the mountains near Bozeman. Ridgetop winds from the W will average 15-20 mph and gust 30-40 mph (a bit lighter further south). Near Bozeman, several inches of snow should fall today with several more tonight (3-6” total). Further south, 2-3 inches should fall by tomorrow morning.
Persistent slab avalanches 2-4 ft deep remain the main concern and reports of avalanches and collapsing continue to trickle in (scroll through the weather & avalanche log). There hasn’t been a widespread avalanche cycle, but snowfall on 12 of the last 13 days has kept the snowpack somewhere near its breaking point.
The reason for these avalanches is a layer of weak facets from dry weather in early December. Some surface hoar was buried as well, mostly near Cooke City. I’m hopeful that recent snowfall is helping to heal this layer, but it is still producing avalanches so I’m not ready to trust it.
There’s a lot of fresh powder for winds to move today. Wind slab avalanches on the downwind side of ridges and gullies will become more likely to trigger. A more serious problem will be the increased likelihood of persistent slab avalanches happening on these wind-loaded slopes.
Today the avalanche danger is CONSIDERABLE. I’m unsure of the exact likelihood of triggering an avalanche on any given slope, but I’m sure that safe travel requires cautious route finding and conservative decision making.
Avoid slopes being loaded by today’s winds. IF you choose to enter the peripheries of avalanche terrain, think about (1) where an avalanche would take you, (2) what the consequences would be, and (3) if your partners are watching from a safe location with the gear and training to dig you out quickly.
The Bridger Range is loaded with fresh powder (44 inches over the last week - the old news). Increased downhill winds moved some snow yesterday, and increased winds today will move even more snow (the new news). A good heads up has been several recent wind slabs including one on Monday on South Saddle Peak. This avalanche ran 1500 vertical feet, broke 6 inch diameter trees, and piled debris 20 feet deep.
Wind slab avalanches are the primary problem today. Winds will continue moving snow and human triggered avalanches will be likely. There haven’t been any reports of persistent slab avalanches breaking deeper in the snowpack, but everything has a breaking point and slopes with heavy wind loading could reach that point.
With snow available for transport, more falling this afternoon, and increased winds, the avalanche danger is CONSIDERABLE. Seek out slopes without wind-drifted snow which may become harder to find depending on what winds do today.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
TONIGHT in Idaho Falls, 7-9:30 p.m., Avy Savvy Night at the Colonial Theater. More information HERE.
Avalanche Fundamentals with Field Session for non-motorized travelers THIS WEEKEND. Sign up ASAP or sign up for one on the last weekend of January.
Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.
Yesterday, a skier was killed in an avalanche in Colorado (initial report from CAIC). On Sunday a skier was killed, and a second sustained injuries in an avalanche in western Wyoming (preliminary information from BTAC). Our hearts go out to the skiers’ friends and family, backcountry partners, and the rescue teams.
Thank you for sharing observations. Please let us know about avalanches, weather or signs of instability via the form on our website, or you can email us at mtavalanche@gmail.com, or call the office phone at 406-587-6984.