Archived Advisories

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Snowpack and Avalanche Discussion Attached images Attached Videos
Mar 28, 2017 - Doug Chabot
Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityNew snow (.3-.5” snow water equivalent) combined with wind is drifting snow into slabs near the ridgelines which could be triggered. A supportable 6-8” thick ice crust is underlying the snow from the weekend. Our two dry snow concerns are triggering freshly formed wind slabs and releasing loose snow avalanches (sluffs) that can run for long...
Loose snow avalanches, N. Bridgers
Loose snow avalanche 1, N. Bridgers
Wet loose avalanche, Cooke City
Low Avalanche Danger (for now), Beehive Basin 25 March 2017
Mar 27, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CityA couple inches of snow overnight with light to moderate wind contributes little to the avalanche hazard today. Freezing overnight and cool daytime temperatures for multiple days have preserved a thick crust below last night’s snow, which creates a generally stable snowpack. Over the...
Loose snow avalanches, N. Bridgers
Loose snow avalanche 1, N. Bridgers
Low Avalanche Danger (for now), Beehive Basin 25 March 2017
Mar 26, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CityFreezing overnight temperatures and cool days have maintained a thick, supportable crust at the surface of the snowpack on all except for shady high elevation slopes. The snowpack is generally stable and avalanche concerns are confined to a few inches of recent snow. Eric was in Beehive...
Loose snow avalanches, N. Bridgers
Loose snow avalanche 1, N. Bridgers
Deep wet loose slide in Beehive
Mar 25, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CityEarly morning snow showers urge an increase in avalanche danger today. The forecast is for light snow accumulations and calm wind, but the forecast could be wrong and just a few inches of snow will create small hazards. New snow will bond poorly to firm crusts and make loose avalanches...
Dry slab avalanches, Cooke City 3/23/17
Spring Snow, Wet Avalanche Potential - 24 Mar 2017
Mar 24, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityIt’s not snowing but at least it cooled off. Below freezing temperatures overnight combined with clear skies will produce a firm and locked up snowpack during the first half of the day. On all but high north facing slopes, a solid curst will exist on the snow surface creating stable conditions.As the day progresses, snow conditions...
Dry slab avalanches, Cooke City 3/23/17
Wet loose avalanche, Cooke City
Pinwheels and Point Releases  - Texas Meadow
Cornice up Hyalite
Mar 23, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityIt’s a choose your own adventure type of day. Dry snow still exists on high north facing slopes while spring corn conditions can be found if timed right on south facing and lower elevation terrain.The snow will change quickly today. A surface crust that formed overnight due to below freezing temperatures will break down when exposed to...
Wet loose avalanche, Cooke City
Pinwheels and Point Releases  - Texas Meadow
Cornice triggered avalanche N. Bridgers
Mar 22, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin RangeLionhead area near West Yellowstone Cooke CityWet avalanches will occur today. Temperatures will rise and the sun will shine, warming and melting the snow. A thick and supportable ice crust 6-12” deep is a perfect sliding surface for the wet snow (photo). Expect natural, point release avalanches on slopes getting baked by the sun. Wet avalanches will be easy to trigger. Signs that...
Ice Crust under the new snow
Pinwheels and Point Releases  - Texas Meadow
Mar 21, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin Range Cooke CityLionhead area near West YellowstoneNew snow, above freezing temperatures, winds and a moist snowpack create a messy avalanche forecast. There are many variables changing hourly that are near impossible to keep track of, but all is not hopeless. Assessing stability is a step-by-step process. Under the new snow, the old surface is either wet or frozen. At the lowest elevations...
Wet avalanches are right around the corner
Mar 20, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Cooke CityLionhead area near West YellowstoneTrue to form, spring began with change. Wet snow was the concern this weekend, and today is colder with new snow. Below freezing temperatures since yesterday froze the upper few inches of a previously wet, non-cohesive snowpack, and avalanches are unlikely to break on layers below the new snow. Wind...
Cornice triggered avalanche N. Bridgers
Roller balls_2
Cornice up Hyalite
Mar 19, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Cooke CityLionhead area near West YellowstoneAbove freezing temperatures yesterday led to a wet, weak snowpack on all but the highest, shadiest slopes. Near and below freezing temperatures this morning will refreeze the snow surface and lower the potential to trigger wet avalanches. A thin breakable crust may be the extent of freezing on warmer...
Roller balls_2
Cornice up Hyalite
Mar 18, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Cooke CityLionhead area near West YellowstoneTemperatures did not drop below freezing last night. However, clear skies allowed for radiational cooling, which will firm up the snow surface. This will eliminate the wet snow avalanche hazard during the early morning hours.The surface crust will break down quickly under the influence of sun and warming temps. By late morning-early afternoon...
Roller balls_2
Cornice up Hyalite
Mar 17, 2017 - Eric Knoff
Cooke CityThe mountains around Cooke City got lucky last night and picked up 6-8” of snow totaling .8” of SWE. This new snow will improve riding conditions, but it will also bump up the avalanche danger. Wind slabs and wet loose avalanches will both be a concern today. Wind slabs will be most widespread on upper elevation slopes leeward to W-SW winds. These won’t be exceptionally large, but they could pack...
Roller balls_2
Cornice up Hyalite
Wet avalanches
Mar 16, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityToday, wet snow avalanches are the primary concern. Below 9,000’, temperatures have not dropped below freezing for multiple days (video). The lack of freezing temps combined with the potential for rain today will produce unstable conditions, mainly on mid to low elevation slopes. Obvious signs on instability such as roller balls and...
Roller balls_2
Cornice up Hyalite
Natural avalanche on Fan Mountain 2
It's still winter above 9,000 feet: Buck Ridge
Mar 15, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin RangeLionhead area near West Yellowstone Cooke CityThe mountains are in a transition with a battle being waged between winter and spring. Yesterday, Eric and I rode our sleds into Buck Ridge and discovered winter still flexing her muscles at the higher elevations (video). She won that round, but that was yesterday. Today will be different because sunshine and above freezing temperatures will...
Roller balls_2
Cornice up Hyalite
Natural avalanche on Fan Mountain 2
It's still winter above 9,000 feet: Buck Ridge
Mar 14, 2017 - Doug Chabot
RAINWith rain comes avalanches. A drizzle will not affect the stability, but a hard rain would quickly weaken the snow and trigger avalanches. Heavy rain is not forecasted, but forecasts can be wrong. Rain is the starting pistol to get out of avalanche terrain; think, “Run, Forrest, run!” And really, who wants to be out in the rain anyway.Bridger Range Madison Range Gallatin RangeLionhead area near West Yellowstone...
Cornice triggered avalanche
Surfing a large cornice
Avalanche on wind loaded slope near Cooke
Natural avalanche on Fan Mountain 2
Mar 13, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range  Lionhead area near West Yellowstone   Cooke CityStrong west to southwest wind through the last week drifted new snow into slabs that are possible to trigger today. These slabs range from 6 inches thick in the mountains near Bozeman to 6 feet thick near Cooke City. The most suspect slopes are below ridgelines and near large cornices....
Hole behind cornice in Hyalite
Avalanche on wind loaded slope near Cooke
Natural avalanche on Fan Mountain
Snowmobile triggered cornice on Black Mountain near Lionhead
Large cornices in Middle Basin
Mar 12, 2017 - Alex Marienthal
Cooke City   Lionhead area near West Yellowstone  Madison Range   Southern Gallatin RangeNear Cooke City, West Yellowstone, and Big Sky heavy snowfall and strong wind over the last week create our main avalanche concerns today. The mountains near Cooke City got 4-5 feet of snow, and 2-3 feet of snow fell near West Yellowstone and Big Sky since last Sunday. Good news is there are no widespread...
Avalanche on wind loaded slope near Cooke
Natural avalanche on Fan Mountain 2
Natural avalanche on Fan Mountain
Snowmobile triggered cornice on Black Mountain near Lionhead
Cooke City Avalanches - 3/10/17
Large cornices in Middle Basin
Mar 11, 2017 - Alex Marienthal
Wet Snow: Warm temperatures and sunshine today will moisten the snow surface and make wet loose avalanches likely on steep slopes. Avalanche danger could rise to CONSIDERABLE on all slopes by late morning. Avoid steep slopes if you see roller balls or can make snowballs with damp snow on the surface.Cooke CityThe mountains near Cooke City got 4-5 feet of snow totaling over 5” of snow water equivalent (SWE) in the last...
Large natural slide in Sheep Creek near Cooke
Snowmobile triggered cornice on Black Mountain near Lionhead
Cooke City Avalanches - 3/10/17
Large cornices in Middle Basin
Mar 10, 2017 - Eric Knoff
Cooke CityAlthough more snow fell overnight, the avalanche warning for mountains around Cooke City has expired. Since yesterday morning, Fisher Creek Snotel site picked up 8-10” of dense snow totaling 1.2” of SWE. This puts the three day total at 3.4” of (snow water equivalent).Winds over the past 24 hours have decreased slightly, but are still blowing hard enough to transport snow. Today, natural and human...
Triggering wind slabs at Lionhead
Mar 9, 2017 - Eric Knoff
Cooke CityOnce again the mountains around Cooke City are in a league of their own. Over the past 24 hours this area has received over a foot of snow totaling 1.5” of SWE. This puts the 48 hour total at more than 2’ of snow totaling 2.2” of SWE. This heavy amount of snow has been accompanied by strong winds out of the W-SW. This combination will create unstable conditions on all slopes (photo). Today, continued...
Lick Creek Avalanche
Triggering wind slabs at Lionhead
Soft slabs in new snow 2
Mar 8, 2017 - Doug Chabot
Lionhead area near West Yellowstone Cooke CitySince Saturday evening Cooke City and Lionhead have gotten 20” of snow (2” SWE). Winds have been strong out of the W-SW and drifts are thick, dense and ready to avalanche. Eric and I rode into Lionhead and pinned the throttle multiple times to plow through whale-sized drifts. Cracks would shoot out in front of the sled and in one spot we were able to trigger a small wind-...
Lick Creek Avalanche
Triggering wind slabs at Lionhead
Soft slabs in new snow 1
Mar 7, 2017 - Doug Chabot
Gallatin Range Madison Range Lionhead area near West Yellowstone Cooke CityAll the mountains south of Bozeman have gotten 8-12” of snow in the last 36 hours totaling .7-1” of snow water equivalent (SWE). Wind is blowing hard out of the west and drifting this snow into thick wind slabs that will be easy to trigger. The winds are also feeding cornices at the ridgetop making the overhangs ripe for calving. On Saturday,...
Soft slabs in new snow 2
Soft slabs in new snow 1
Skier triggered slab S. Madisons 2
Complex snowpack, complex terrain, Bridgers - 4 Mar 2017
Mar 6, 2017 - Alex Marienthal
Gallatin Range   Madison Range  Cooke CityLionhead area near West Yellowstone  New snow improves the skiing and riding on all aspects today, and increases the avalanche danger. Avalanches are easy to trigger where new snow did not bond well to the old surface, such as sun crusts on southerly aspects. New snow will bond better on slopes sheltered from sun and wind that held dense powder yesterday, or...
Mar 5, 2017 - Alex Marienthal
Bridger Range  Madison Range   Gallatin Range  Lionhead area near West Yellowstone   Cooke CityStrong wind and warm temperatures the last three days sculpted the snow surface to a different quality than last week’s powder frenzy. Wind scouring, minimal snowfall, and a melt-freeze of the surface have promoted stability, but created variable riding conditions. Good skiing and riding is found...
Mar 4, 2017 - Eric Knoff
Bridger Range  Madison Range  Gallatin Range Lionhead area near West Yellowstone  Cooke CityWarm weather yesterday with little wind helped promote stability. Yesterday, Alex and I skied near Hebgen Lake and found the snow surface to be damp on all but northerly aspects. Today, a melt-freeze crust will be present on sun exposed slopes. This will create rough riding but stable conditions. It will also limit...
Weak layer, but overall strong - Hebgen, 3 Mar 2017
Mar 3, 2017 - Eric Knoff
Cooke CityThe mountains around Cooke City have picked up over a foot of snow this week. In addition to consistent snowfall, strong winds have impacted the area. This combination has produced unstable conditions in isolated areas. On Wednesday, a skier south of town triggered two avalanches in non-wind loaded terrain, one remotely. These slides broke 12-16” deep and failed on a facet-crust combination beneath the new snow (...
New Snow Instabilities, Cooke City 3/1/17
Natural Avalanche, Tepee Basin 3/1/17
"Right here, right now, we're looking pretty good" Saddle Peak
Mar 2, 2017 - Eric Knoff
Cooke CityThe mountains around Cooke City have picked up measurable snowfall every day for the past six days. Fisher Creek Snotel site is recording 1.1” of snow water equivalent since last Saturday. This incremental loading has started to produce unstable conditions. Yesterday, a skier south of town triggered two avalanches in non-wind loaded terrain, one remotely. These slides were breaking 12-16” deep and appeared...
New Snow Instabilities, Cooke City 3/1/17
Natural Avalanche, Tepee Basin 3/1/17
"Right here, right now, we're looking pretty good" Saddle Peak
Mar 1, 2017 - Doug Chabot
Bridger RangeYesterday, Eric and I went to Saddle Peak to check on stability. This area had feet of snow from the weekend (4-6’ of powder snow measuring 1.5” of snow water equivalent) and winds. We anticipated finding wind slabs, but did not. Instead we found mostly stable conditions (video). The weekend’s snow bonded well to the old surface, did not weigh much and fell onto a snowpack without prominent weak...
"Right here, right now, we're looking pretty good" Saddle Peak
Feb 28, 2017 - Doug Chabot
Bridger RangeSince Friday night the Bridger Range has gotten 4-6’ of low-density snow measuring 1.5-2” of snow water equivalent (SWE). That equates to 3% powder, or 97% air. Although the weight is not a big burden the winds are blowing and drifting snow at all elevations, not just the ridgelines. On Saturday Eric was in the northern Bridger Range (video) and on Sunday Alex toured north of the ski area (video). Their...
Skier triggered new snow avalanche in northern Bridgers 2
Crown of Skier triggered avalanche in northern Bridgers