Archived Advisories

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Snowpack and Avalanche Discussion Attached images Attached Videos
Apr 10, 2017 - Alex Marienthal
Spring is an active time in the mountains. Weather and snow conditions can change quickly, and a range of weather produces a variety of avalanche problems. Here are some avalanche concerns to keep in mind:(For more information on spring avalanche problems and travel advice see a couple recent videos from the end of this season (video 1, video 2), or this article.)1. NEW SNOW AND WIND-LOADINGSpring storms are notorious for...
Spring Sled Fest in Cooke City
Apr 9, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CityToday’s new snow makes dry and wet loose avalanches possible in steep terrain. These slides can run long distances and become large where a firm crust lies below the new snow. In areas that got more snow, dense slabs of new snow are possible for a skier or rider to trigger.Fresh...
Spring Sled Fest in Cooke City
Apr 8, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CityAbove freezing temperatures yesterday followed by rain and snow create a mix of spring snow conditions today. Before rain and snow fell last night the snowpack was wet and not frozen up to 10,000’ near Bozeman. New snow insulates weak unconsolidated snow where the snowpack did...
Spring Sled Fest in Cooke City
Snowpack is changing daily
Apr 7, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityClouds won’t cover all of southwest Montana until this afternoon. With temperatures in the mid-40s in the northern ranges, a few hours of sunshine would be enough to create wet loose avalanches, even with a “cooling” wind. Pinwheels rolling downhill is a sign of the surface snow becoming unstable. Winds last night were...
Wind transport, Beartooths
Snowpack is changing daily
Apr 6, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityYesterday, cooler temps and cloudy skies kept the wet snow avalanche danger at bay. Today, warmer temps and periods of sun could produce wet loose avalanches on sun exposed slopes. Roller balls and pinwheels are the first sign that wet-loose avalanches can quickly follow video. Fortunately, partly to mostly cloudy skies combined with...
Wind transport, Beartooths
Climber triggered slide on Beehive Peak 3
Snowpack is changing daily
Apr 5, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CitySpring is an amazing time. You can ski in the morning and golf in the afternoon. Today will be Taylor Made for both activities. Skiing or riding will be best early in the day before sun and warming temps soften the snow surface. On all but due north facing slopes, wet loose avalanches will be the primary problem.Over the past few days, a few...
Natural Avalanches, Tobacco Roots 4/4/17
Climber triggered slide on Beehive Peak 3
Snowpack is changing daily
Apr 4, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityAs Mister Roger’s said, “It’s a beautiful day in the neighborhood.” In the last three days a few inches of new snow with cold temperatures increased the riding and sliding value yet did not raise the avalanche danger. Yesterday I did a long snowmobile tour into Lionhead and found stable conditions. Under the new snow...
Middle Basin Snowpit Profile
Climber triggered slide on Beehive Peak
Snowpack is changing daily
Apr 3, 2017 - Alex Marienthal
Lionhead area near West YellowstoneThe mountains near West Yellowstone got 3-5” of snow last night, and moderate wind this morning is forming fresh drifts of snow that could be triggered by a skier or rider. Be extra cautious of steep wind loaded slopes, or avoid them altogether. Cornices are huge and can break far back from the edge. Give these monsters a lot of distance and avoid slopes directly below. The avalanche...
Snowpack structure is changing rapidly
Climber triggered slide on Beehive Peak 2
Climber triggered slide on Beehive Peak
Wind Slab, Mt Blackmore 3/31/2017
Snowpack is changing daily
Apr 2, 2017 - Alex Marienthal
Bridger Range   Madison Range   Gallatin Range   Lionhead area near West Yellowstone   Cooke CitySnow, wind, sunshine, and warm temperatures created heightened avalanche danger this weekend (video, video). Today, more snow and possibly rain contribute to the mix of avalanche problems to look out for. Eric was near Bridger yesterday and summarized conditions as “full on...
Climber triggered slide on Beehive Peak 2
Climber triggered slide on Beehive Peak
Wet loose avalanches, Saddle Peak 4/1/17
Wind Slab, Mt Blackmore 3/31/2017
Apr 1, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityToday, wet loose avalanches will be the primary concern. The snow that fell Wednesday night and Thursday morning will move easily when exposed to direct sun and warming temps. Yesterday, my partner and I took a final tour up Hyalite and found 8” of new snow above 9,000 feet. The new snow was dense and contained more than 1” of SWE...
Wind Slab, Mt Blackmore 3/31/2017
Wet loose avalanches -  Bridger Bowl
Dry loose slide - Mt Blackmore
Glued on to unglued, it won't take much - 31 March 2017
Mar 31, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityYesterday, loose snow avalanches were observed in the Bridger Range (photo), northern Gallatin Range (photo) and northern Madison Range. In upper elevation terrain, these slides would be considered dry loose avalanches. On mid to lower elevation slopes, mainly in the Bridger Range, these slides occurred as wet loose avalanches. Either way,...
Wet loose avalanches -  Bridger Bowl
Dry loose slide - Mt Blackmore
Mar 30, 2017 - Eric Knoff
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityThe current weather pattern will create a variety of avalanche problems today. On mid to low elevation slopes, above freezing temps and rain will increase the wet snow avalanche hazard. The thick surface crust that formed the past few days will hold up this morning, but the snowpack will become soft and unsupportable as the day progresses,...
Skier triggered avalanche - Cooke City
Wet, loose avalanches
Slab avalanche on steep terrain
Mar 29, 2017 - Doug Chabot
Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityToday is a day of transition as another storm approaches. This morning sun will dampen the snow surface creating the possibility of wet loose avalanches. This danger will be short lived as increasing cloud cover and wind will keep significant melting at bay. Later this afternoon rain may occur at lower elevations. Rain on snow is bad and...
Wet, loose avalanches
Slab avalanche on steep terrain
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