This wet loose avalanche is a great example of where they often occur. Rocks absorb extra heat from the sun and can quickly melt and destabilize the snow. Either move under areas like this early in the morning (as we did), or if you have to travel under them later in the day, move quickly.
Trip Planning for Southern Madison
Primary Problem: Loose Wet
Bottom Line: Today and this weekend, the main threat is wet snow avalanches. A minimal refreeze of the snow this week combined with very warm weather the next few days will increase the odds of wet loose avalanches. Past 5 Days
Sun Apr 20
Low
Low
Mon Apr 21
None
None
Fri Apr 25
None
None
Mon Apr 28
None
None
Fri May 2
None
None
Relevant Photos
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Understanding Avalanche Safety Preparedness – 5-Minute Survey for Motorized Users
We need your input! Eastern Oregon University is conducting a survey to better understand avalanche safety preparedness among motorized backcountry users like you. Your feedback will help us learn more about who is purchasing and practicing with avalanche rescue gear (beacon, probe, shovel) and participating in avalanche education—and why some riders aren’t. The survey is confidential and anonymous.
Your feedback is invaluable in improving avalanche education and awareness. Please take a moment to share your experience and help us make a difference.
https://eoustmhs.qualtrics.com/jfe/form/SV_3L8QKAuZzcxJBLo
Thank you for your time and for being a part of this important effort!
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Snowmobile triggered slide in Taylor Fork today from above cutting across. Nobody caught. 2.5 feet deep 150 feet wide
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Snowmobile triggered slide in Taylor Fork today from above cutting across. Nobody caught. 2.5 feet deep 150 feet wide
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Persistent slab avalanche from (3/19) in Sunlight Basin, Taylor Fork. Photo: Anonymous
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Persistent slab avalanche from (3/19) in Sunlight Basin, Taylor Fork. Photo: Anonymous
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We rode into Tepee Basin and to the north wilderness boundary. There was 1.5-2 feet of new snow that fell since Thursday. We dug (3) snowpits on northeast, north and southeast slopes, between 8800'-9200'. The pits on northerly slopes had ECTP 17 and 22 on a thin weak layer below the new snow. We also had ECTP 6 within the storm snow. Photo: GNFAC
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On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
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On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
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On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
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On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
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On March 15 We looked at the avalanche in Sunlight Basin/Taylor Fork that was triggered by a snowmobiler yesterday (Mar 14). It was 50' wide, 100' vertical, 2-3' deep hard slab with 8-9" new snow on top. Broke on weak facets buried in late January. Dirt layer from Feb 4 was visible 6-8" above weak layer. Bed surface was 3" to 1.5' deep of weak, sugary facets. Slope angle was 38-40+ degrees. 8800', WNW aspect. Photo: GNFAC
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On Mar 14 A group of riders shared that they had triggered a 4' deep slide in a small pocket in Sunlight Basin of the Taylor Fork area. It was in an area with a relatively shallower snowpack, and broke on weak snow near the bottom of the snowpack. The rider that triggered it was going uphill and got stuck shortly after and noted the snowpack was much deeper there.
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Another day of warm temps and clear skies allowed us to cover a lot of ground in the Southern Madisons. We rode into the Taylor Fork, up to the weather station, to the top of Carrot Basin, through Sage Basin, up and over into Cabin Creek, and all the way up to the head of Red Canyon.
There were a handful of small wet-loose avalanches on solar aspects that we noted throughout the day. While northerly aspects stayed cold, solar aspects became wet a couple inches down. Photo: GNFAC
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Another day of warm temps and clear skies allowed us to cover a lot of ground in the Southern Madisons. We rode into the Taylor Fork, up to the weather station, to the top of Carrot Basin, through Sage Basin, up and over into Cabin Creek, and all the way up to the head of Red Canyon.
There were a handful of small wet-loose avalanches on solar aspects that we noted throughout the day. While northerly aspects stayed cold, solar aspects became wet a couple inches down. Photo: GNFAC
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Photo taken Mar 1 by GNFAC
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We also spotted an old wind slab avalanche (R1-D2) that broke earlier this week in Sunlight Basin. Photo: GNFAC
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On Mar 1 we also spotted one older cornice-fall triggered avalanche in Sunlight Basin. Photo: GNFAC
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On Mar 1 we also spotted two cornice-fall triggered (R2-D2) avalanches that broke earlier this week - one in Sunlight Basin and one in Sage Basin. Photo: GNFAC
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On Mar 1 We also spotted one cornice-fall triggered (R2-D2) avalanche that broke earlier this week in Sage Basin. Photo: GNFAC
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At the top of Carrot Basin, we saw a small avalanche (R1-D1) on a N aspect that likely broke yesterday on buried weak layers. Photo: GNFAC
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At the top of Carrot Basin, we saw a small avalanche (R1-D1) on a N aspect that likely broke yesterday on buried weak layers. Photo: GNFAC
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A rider triggered a huge avalanche in the uppermost reaches of Targhee creek on a north facing slope at 9200'
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A rider triggered a huge avalanche in the uppermost reaches of Targhee creek on a north facing slope at 9200'
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A rider triggered a huge avalanche in the uppermost reaches of Targhee creek on a north facing slope at 9200'
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From IG message: "Getting word that a group triggered a decent slide today out at cabin creek. I’ll attach the coordinates to the general area, to the best of my knowledge.
44.86484, -111.22023No burials. They were able to outride if. But thought I’d send coordinates in case you guys were gonna be in the area and wanted to check it out."
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From IG message: "Getting word that a group triggered a decent slide today out at cabin creek. I’ll attach the coordinates to the general area, to the best of my knowledge.
44.86484, -111.22023No burials. They were able to outride if. But thought I’d send coordinates in case you guys were gonna be in the area and wanted to check it out."
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Snowmobile triggered avalanche likely on Saturday, Feb 22. It appeared that no one was caught or buried.
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Snowmobile triggered avalanche that resulted in a partial burial with no injuries on Friday, Feb 21.
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Snowmobile triggered avalanche that resulted in a partial burial with no injuries on Friday, Feb 21.
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From IG message: "We remotely triggered this hillside in Taylor's fork yesterday [2/21] from the Ridgeline above it. We were looking for a safe spot to drop down when it released below us. Circled around for some pictures. The snow was pretty shallow, only 2-3 feet deep, and slid to the ground. South facing slope"
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From IG message: "We remotely triggered this hillside in Taylor's fork yesterday [2/21] from the Ridgeline above it. We were looking for a safe spot to drop down when it released below us. Circled around for some pictures. The snow was pretty shallow, only 2-3 feet deep, and slid to the ground. South facing slope"
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From IG message: "We remotely triggered this hillside in Taylor's fork yesterday [2/21] from the Ridgeline above it. We were looking for a safe spot to drop down when it released below us. Circled around for some pictures. The snow was pretty shallow, only 2-3 feet deep, and slid to the ground. South facing slope"
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There was a thin melt/freeze crust formed on solar aspects lower down (up to ~500 feet above the parking). Photo: BP
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From email: "One of my crew was partially buried in an avalanche today(head about 1’ down, leg and arm still above snow) at approximately 13:10 hrs. Slope was greater than 35 degrees, crown approximately 85 yards wide, over 3’ at its thickest point. I believe it was a NE exposure with wind loading at the top. I had a bad feeling about this slope and mentioned it to my crew and avoided riding on it until one rider ran out of gas and I had to help him. Upon completion of task, I rode back to a spot that wasn’t as safe a vantage point as what I had previously stayed at, but the intention was we were all on our way out. So I parked and within 30 seconds, I hear my friend yelling behind me. I turn and immediately think “oh he’s about to hit us”. So, I attempted to start up my sled, to no avail While watching behind me. Suddenly, a massive “snow cloud” appeared about 30 yards above him and it took about 2-4 seconds to register that it was an avalanche and not another rider careening out of control at us. By that time, it was too late to do anything. The avalanche had reached the back of my friend and my sled, pushing us forward about 6 feet at 3-4mph. After it stopped, I assessed 3 of four of our team was accounted for, and one (the one who yelled at us) was not. He was partially buried by the front of the avalanche much like our sleds were. Fortunately, within 5 seconds, I saw an arm and a leg sticking out of the snow and we had his airway and head cleared within about 20 seconds. He was located approximately 10 yards from us. "
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From email: "One of my crew was partially buried in an avalanche today(head about 1’ down, leg and arm still above snow) at approximately 13:10 hrs. Slope was greater than 35 degrees, crown approximately 85 yards wide, over 3’ at its thickest point. I believe it was a NE exposure with wind loading at the top. I had a bad feeling about this slope and mentioned it to my crew and avoided riding on it until one rider ran out of gas and I had to help him. Upon completion of task, I rode back to a spot that wasn’t as safe a vantage point as what I had previously stayed at, but the intention was we were all on our way out. So I parked and within 30 seconds, I hear my friend yelling behind me. I turn and immediately think “oh he’s about to hit us”. So, I attempted to start up my sled, to no avail While watching behind me. Suddenly, a massive “snow cloud” appeared about 30 yards above him and it took about 2-4 seconds to register that it was an avalanche and not another rider careening out of control at us. By that time, it was too late to do anything. The avalanche had reached the back of my friend and my sled, pushing us forward about 6 feet at 3-4mph. After it stopped, I assessed 3 of four of our team was accounted for, and one (the one who yelled at us) was not. He was partially buried by the front of the avalanche much like our sleds were. Fortunately, within 5 seconds, I saw an arm and a leg sticking out of the snow and we had his airway and head cleared within about 20 seconds. He was located approximately 10 yards from us. "
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Snowmobile triggered avalanche in Teepee Basin.
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Large cornice fall triggered avalanche in Sage Creek, Photo: GNFAC
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This snowpit on a SE aspect was made up of a dense slab of recent snow, sitting on top of many different layers of junky, faceted grains. Propagation was easy to find (ECTP 11, HS: 112). Photo: GNFAC
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We saw up to five recent avalanches from the last few days. 1-2 looked to have failed on PWLs, and the rest were wind slabs. Cornice collapses triggered at least two of these avalanches. Photo: GNFAC
Videos- Southern Madison
WebCams
Raynolds Pass, Looking N
Weather Stations- Southern Madison
Weather Forecast Southern Madison
Extended Forecast for20 Miles S Big Sky MT
Overnight
Low: 30 °F
Rain/Snow
LikelyMonday
High: 32 °F
Snow and
BreezyMonday Night
Low: 23 °F
Snow Showers
Likely and
BlusteryTuesday
High: 39 °F
Slight Chance
Snow Showers
then Mostly
SunnyTuesday Night
Low: 26 °F
Partly Cloudy
Wednesday
High: 48 °F
Sunny
Wednesday Night
Low: 34 °F
Mostly Clear
Thursday
High: 53 °F
Sunny then
Chance
ShowersThursday Night
Low: 35 °F
Slight Chance
Showers then
Mostly Clear
The Last Word
Thank you for another successful season. Our success is directly related to support from our community and the Forest Service. Thanks to the readers of the forecast, everyone that sent in observations, took an avalanche class, or donated money, time or gear. We will issue conditions updates on Mondays and Fridays through April.
GENERAL SPRING SNOWPACK AND TRAVEL ADVICE
Spring weather can be highly variable and create a mix of avalanche problems. Snow conditions and stability can change drastically from day to day or hour to hour. Anticipate rapid change and plan accordingly. Abundant snowfall over the winter with more spring snow to come makes avalanches possible into summer.
NEW SNOW AND WIND LOADED SLOPES
Spring storms are notorious for depositing heavy amounts of snow in the mountains. Even with a deep and generally stable snowpack throughout the advisory area, heavy and rapid loads of new snow will decrease stability. The main problems to look out for are avalanches breaking within the new snow, wind slabs, and loose snow avalanches. The likelihood of triggering an avalanche spikes during and immediately after snowstorms. New snow instabilities tend to stabilize quickly, but it’s a good idea to give fresh snow a day to adjust before hitting big terrain. New snow instabilities can be challenging to assess, and spring storms bond to old snow differently across aspects and elevations. Conservative terrain selection is essential during and immediately following storms. Avoid wind-loaded slopes and slopes steeper than 35 degrees for 24-48 hours after new snow and wind.
New snow can quickly change from dry to wet on a spring day, and stability can decrease rapidly with above freezing temperatures or brief sunshine. New snow may bond well early in the morning and then easily slide later. Wet loose slides are likely during the first above freezing temperatures or sunshine immediately after a storm. Anticipate changes in snow stability as you change aspect or elevation and over the course of the day. An early start is always an advantage. Be ready to change plans or move to safer terrain at the first signs of decreasing stability.
WET SNOW AVALANCHES
Spring and wet snow avalanches go hand-in-hand. Above freezing temperatures, rain, and/or intense sunshine cause the snow to become wet and weak and make wet avalanches easy to trigger or release naturally. Conditions tend to become most unstable when temperatures stay above freezing for multiple days and nights in a row. Avoid steep terrain, and be aware of the potential for natural wet avalanches in steep terrain above you, if you see:
- Heavy rain,
- Above freezing temperatures for more than 24 hours,
- Natural wet avalanches,
- Rollerballs or pinwheels indicating a moist or wet snow surface,
- Or if you sink to your boot top in wet snow.
In general, if the snow surface freezes solid overnight, the snowpack will be stable in the morning and stability will decrease through the day as snow warms up. The snow surface hardness, rate of warming, duration of sunshine, aspect and elevation determine how fast stability will decrease through the day. Be aware that sunny aspects may have a wet snow avalanche danger while shadier slopes still have a dry snow avalanche danger. Getting off of steep slopes should be considered when, or before, the above signs of instability are present. Wet snow avalanches, whether loose snow or slabs, can be powerful, destructive and very dangerous. Conservative terrain choices, starting early in the day, and careful observations can keep you safe.
CORNICES
Cornices along ridgelines are massive and can break under the weight of a person (photo). Prolonged above freezing temperatures and rain make them weaker and possible to break naturally. They can break off suddenly and farther back than one might expect. Cornice falls can also entrain large amounts of loose snow or trigger slab avalanches. Stay far back from the edge of ridgelines and minimize exposure to slopes directly below cornices. Regardless of whether a cornice triggers a slide or not, a falling cornice is dangerous to anyone in its path.
DISCLAIMER
It does not matter if new snow falls or not, avalanches will continue to occur until the existing snowpack is mostly gone. Always assess the slope you plan to ride with diligence and safety in mind. Do not let your guard down. Travel with a partner, carry rescue gear and only expose one person at a time in avalanche terrain.
Have a safe and enjoyable spring and summer!
Mark, Alex, Ian and Dave
For more spring travel advice see this article from our GNFAC forecaster blog.