Trip Planning for Island Park

as of 5:00 am
Today0″ | 20-30 SW
Jan 17 0″ | 15-30 W
Jan 16 0″ | 10-32 W
8775′  01/18 at 17:08
13℉
SW - 11mph
Gusts 18mph
7750′   01/18 at 17:00
21℉
49″ Depth
Bottom Line: The snowpack across the advisory area is generally stable and the expected snow won’t be enough weight to change this. However, new snow will likely bury a feathery layer of weak surface hoar that will be our new layer of concern until proven otherwise. Human-triggered avalanches are unlikely to break deeper than the 1-2” of snow falling today. Test the snowpack, assess for isolated instability and employ safe travel practices if you chose to enter avalanche terrain.
Primary Problem: Persistent Weak Layer

Snow Observations- Island Park & Lionhead

Island Park
Sawtelle Peak
Sawtelle Peak stability evaluation
Incident details include images

We dug at 9300' off the Sawtelle Peak Road to keep tabs on stability since we put out warnings and basic information for this area. We work with the guys who manage the FAA road and they give us access for pit digging. 

The stability in this area seems generally stable. The 2 pits today tracked with our findings last week, as well as what we are seeing in nearby Lionhead. The snow is 6-7 feet with a weak layer of facets near the ground. The  facets are weak, but not unstable. With a big enough load they would be, but for the moment we are optimistic that stability will get better. 

Full Snow Observation Report
Island Park
Sawtelle Peak
Head of White Elephant Canyon

Recent Avalanches? None

Observed Cracking? None

Experienced Collapsing? None

The snowpack is generally quite solid, except for the interface under the storm snow. Use caution on wind loaded slopes that could break at the
bottom of the storm snow layer or within the drifted snow slab. Steep slopes can still pose a problem considering the addition of extra weight coming during the next 24 hours.

Full Snow Observation Report
Island Park
Yale Creek
Yale Creek out of Island Park

Recent Avalanches? None

Observed Cracking? None

Experienced Collapsing? None

Experienced PWL at ground level is alive and well but seems to be healing with the thick insulation layer of snow covering it. Because the snowpack is generally very cohesive on top of the PWL it will be very hard to trigger. The biggest concern is of a couple of slabs of drifted snow in the top 1 to 2 feet of snow. Not sure how widespread the near surface facet layer is, but I found a very touchy layer at high elevation on an east facing slope. this is something to keep in mind after the next storm cycle adds weight and stress to this layer. My biggest concern is of the wind slabs mostly on NE slopes. I observed a lot of blowing snow today that will add weight and stress to these areas. Watch for cracking as you enter wind loaded slopes. It is going to be very difficult to trigger the deep persistent weak layer, what could happen is that a wind slab avalanche could step down into the deeper snowpack triggering a sleeping monster. We don't want to wake him up!

Snow pit location on the east slope of Sawtell. Elevation 7600 ft on north facing 18 degree slope. HS 155cm HN 5cm. Scored ECTN14@132cm and ECTN25@115cm FC confirmed on the ground underneath a MF crust. Although this PWL exists the crystals had some cohesion. About 4F.

Second pit was excavated at 9000ft SW of Sawtell Peak at the head of Yale Creek on an east facing 20 degree slope. HS 255cm HN 8cm. Scored ECTN1@247cm and ECTN17@200cm. I didn't dig down to the facet layer at the bottom of the snowpack, but could feel a strong MF crust at about 35cm off the ground and then very low resistance after poking through the crust into the facet layer. I did identify a surface facet layer at 8cm into the snowpack, just under the new snow, that was very touchy.

Full Snow Observation Report
Island Park
Mt Jefferson Bowl
Avalanche Activity in Centennials, Mt Jefferson

We rode from the Sawtell Road up to Mount Jefferson then through to upper Hell Roaring Creek on a tour of the range and accident sites with three members of the Fremont County SAR team, Randy, Nick and Justin. The ride was a beautiful traverse of the range. There was one very large natural avalanche that failed a week earlier on Mount Jefferson and several others that broke during the last loading event. We dug a couple of snowpits, finding a DEEP (200-230 cm HS) and mostly stable snowpack (ECTXs). Brett Rasmusen found a layer of NSF in the head of the White Elephant drainage and an avalanche nearby at Lionhead is indicative of a more widespread weak layer 1-2’ under the surface. LOW / MODERATE seemed appropriate on deeper instabilities, but with anticipated loading, we must communicate the concern about this new weak layer and the potential for large avalanches breaking in the upper part of the snowpack.

Full Snow Observation Report
Island Park
Centennials - Montana
Centennial Mountains, Tin Cup Pass
Incident details include images

We rode into the Hell Roaring drainage via Willow Creek to Tin Cup Pass from the Keg Springs parking lot in Idaho. There was no recent avalanche activity observed along this route. I dug one pit at Tin Cup Pass on the Montana side at 8000' on a NW aspect. Total snow depth was 165cm and the snowpack was relatively homogenous with the exception of one melt freeze crust near the bottom of the snowpack at 39cm. From the melt freeze crust to the ground the structure was very sugary. A CT and an ECT were completed with results as follows, CT 12 @135cm, CT 28@ 115cm, and ECTN 16@ 150cm. My greatest concern in the snowpack was the melt freeze crust near the bottom of the snowpack.

Full Snow Observation Report
Island Park
Hellroaring Hut
Incident details include images

Skiid the into the Hellroaring Drainage 12/29/21-1/2/22. Did not observe any natural slide activity or indicators of instability during the tour into the hut. Snow depth was consistently 130 cm at 8000'. Skiid W & NW aspects up to 35 degree slope angle. Fair structure + Good Strength = Generally Stable Conditions in the Eastern Centennial.

WNW aspect, 8,000' HS 130 cm
CT3 Q3 @ 20 cm (new snow)
CT20 Q2.5 @60 cm (new snow)
ECT-N+

Full Snow Observation Report
Island Park
Two Top
Two Top Mtn.
Incident details include images

We rode into Two Top Mtn. on the two top Loop Road from the Island Park side. Dug a pit on a road cut on a west aspect and there was 4 feet of snow, 3/4 of it from the recent storm. New snow was right side up and there was minimal old snow to create instability below the new snow at this elevation. Our second pit was at 7,800’, NE aspect, heavily wind loaded. Snow depth was 6 feet and the lower snowpack was very hard and stable. We dug a third pit on a SE aspect at 8,100’. Depth here was 4.5 feet. There was a crust above facets about 1.5 feet above the ground. This layer could be capable of producing avalanches. There was one natural avalanche that occurred during the storm on Lionhead Ridge. We did not see other signs of instability today. Remain cautious of the possibility of avalanches breaking 3 feet deep below the recent large storm.

Full Snow Observation Report
Island Park
Sawtelle Peak
Sawtelle Peak Snowpack
Incident details include images

I drove up the Sawtelle Peak road and dug a pit at the snow marker at 8,800'. There was 1.5 feet (60 cm) of snow on the ground. Around 7,000' the snow was on all aspects, but below that there were melted patches. The snow was supportable and there was no cracking or collapsing. A layer of weak, sugary snow 1 foot off the ground broke clean in stability tests (ECTP 18, 21) and I anticipate this layer will get weaker with time. On the surface there is a thin layer of snow that is faceting and getting weaker. Photos and snowpit are on this page. 

Full Snow Observation Report

Relevant Avalanche Activity

Lionhead Range
Lionhead Ridge
Avalanche near Lionhead Peak
Incident details include images
Lionhead Ridge
SS-N-R3-D2-O
Elevation: 9,000
Aspect: NE
Coordinates: 44.7328, -111.3320
Caught: 0 ; Buried: 0

This avalanche broke wide in a northerly facing bowl off Lionhead Ridge. It looks to have broken a foot or less deep. The propogation indicates a uniform weak layer, likely near-surface facets or surface hoar.


More Avalanche Details
Island Park
Mt Jefferson Bowl
Avalanche Cycle in the Centennial Mtns
Incident details include images
Mt Jefferson Bowl
HS-N
Coordinates: 44.5658, -111.5000
Caught: 0 ; Buried: 0

A large avalanche cycle occurred around Mt Jefferson, Reas Peak and Hellroaring Creek around the 28th of December. Slides ran on faceted snow near the ground and they propagated far and wide. 


More Avalanche Details

Relevant Photos

Displaying 1 - 27
  • Riders reported on 1/15/22: "Some surface hoar is forming on nearly every aspect at all elevations. over 1 cm thick in some areas." Photo: B. Rasmussen

  • Riders reported on 1/15/22: "Some surface hoar is forming on nearly every aspect at all elevations. over 1 cm thick in some areas." Photo: B. Rasmussen

  • Settlement rings around the base of trees near Cooke City, January 15, 2022. Photo: B. Fredlund

  • Ian Hoyer stands in the 7 foot deep snowpit we dug to look at layering and stability. Stability was good. We dug at 9300' off the Sawtelle Peak Road to keep tabs on stability since we put out warnings and basic information for this area on our Trip Planning page. Photo: GNFAC

  • The crown line is visible on the shaded face in the middle of the picture. Large avalanches released naturally during the week of 12/27 in the Centennial Mountains outside Island Park. Photo: GNFAC

  • Large avalanches released naturally during the week of 12/27 in the Centennial Mountains outside Island Park. Photo: GNFAC

  • Large avalanches released naturally during the week of 12/27 in the Centennial Mountains outside Island Park. Photo: GNFAC

  • Behind the sledders are deep piles of debris from an avalanche cycle a week ago in the Mt. Jefferson area near Island Park. Photo: GNFAC

  • A sled was recovered uphill of the 2 avalanche victims in the same area it was stuck. The sled was found with a probe line and is buried 3-4 feet deep. The avalanche crown can be seen in the upper slopes above them. Photo: GNFAC

  • The crown of the avalanche that killed two snowmobilers on December 27, 2021 was 300 feet wide and 4-5 feet deep. Photo: GNFAC

  • These are the two sites where the 2 snowmobilers were recovered. They were buried 4-5 feet deep in debris piles that measured 9 feet deep. Photo: GNFAC

  • Ian Hoyer stands next to the crown where we dug a snowpit and investigated the snow structure. The crown averaged 4-5 feet deep. Near his right knee is the layer of weak faceted snow that broke 40 cm above the ground. Above this layer was a thick slab of windblown snow. Photo: GNFAC

  • Dave Zinn of the GNFAC gets 3 layers breaking in his Extended Column Test. About 3 feet of snow fell in the last 4 days which got blown into wind slabs. The weight of the new snow is also creating instability on a weak layer of sugary facets near the ground. Photo: GNFAC

  • Located off Lionhead Ridge outside West Yellowstone, this natural avalanche likely released after the large storm ended Wednesday, December 15. This slope is SE facing and the crown is about 9,400 feet. Faceted snow at/near the ground was the likely weak layer that avalanched. Photo: GNFAC

  • Snowpack on Two Top Mtn. near Island Park, ID on 12/17/21. More than 3 feet of snow fell last week and it was right side up and generally stable. There is some weak snow and crusts near the ground, but we are not seeing signs that these layers are unstable yet. Photo: E. Knoff

  • A skier in the Southern Madison Range remotely triggered this avalanche in the Bacon Rind area from a flat bench above the slope. It broke over 50-75' away where the slope got steeper. Human-triggered avalanches are likely. Avoid steep terrain until the snowpack stabilizes. Photo: Anonymous 

  • From obs: 12/12/21: "Heavy wind loading from gusty SW winds and recent snowfall. Made for some touchy conditions. This was at 9100’ between Sage and Sunlight basins." Photo: JR Mooney

  • At Lionhead Ridge, strong winds are drifting snow into unstable slabs. On steep rollovers, we observed shooting cracks and one large collapse, or "whumph." With more wind and snow in the forecast, expect conditions to get more dangerous before they improve. Photo: GNFAC

  • New snow was blown into thick drifts that can be triggered by skiers or riders. Cracking like this is a sign that drifts are unstable and could slide on steeper slopes. Photo: GNFAC

  • From email (12/5/21) : "Small avalanche triggered while approaching ice climb in East fork of Hyalite basin. 

    Another D1 natural avalanche was observed later in the day similar aspect/elevation

    NE @7600’
    SS-AFu-D0.5-I"

    Photo: A. Schoening

  • Skiers on Mount Blackmore observed cracking within the freshly wind-loaded snow on a southeast-facing slope just below the ridge (11/24/21). Photo: J Schack

  • The snow was breaking 1 foot off the ground in the layer at the blue crystal card. Weak, sugary snow broke and propagated in the extended column test with 18 and 21 taps. We anticipate this weakness to get worse in the coming weeks. Photo: GNFAC

  • There was almost 2 feet of snow (60 cm) at 8800' on NE aspect of Sawtelle Peak. Weak snow (facets) is forming a foot off the ground and were breaking consistently in stability tests. Photo: GNFAC

  • Snowcover on Lionhead ridge begins at about 7,000' in elevation on 11/16. Snowmobiling or skiing from Targhee Pass looks very thin and patchy. Photo: GNFAC

  • Taken on 11/16, consistent snow on all aspects begins around 7,000 feet. 1.5-2 feet of snow is found above 8.500'. Photo: GNFAC

  • From e-mail 11/7/21: "...Once in airplane bowl we saw multiple large slides that ran last night, syn-storm. Most of which came down from the East face of Sac. A few 200-300’ wide and running the length of the bowl.,,, attached is a grainy cell phone pic of the slides in Airplane Bowl." -Anonymous.

  • From email 11/4/21: "...noticed two small wet loose avalanches in the east facing bowl between Pomp and Hardscrabble Peaks." Photo: H. Darby

Snowpit Profiles- Island Park

 

Select a snowpit on the map to view the profile image

Weather Forecast- Island Park

Extended Forecast for

10 Miles ESE Lakeview MT

  • Tonight

    Tonight: A 40 percent chance of snow.  Mostly cloudy, with a low around 12. South southwest wind 6 to 8 mph.  Little or no snow accumulation expected.

    Chance Snow

    Low: 12 °F

  • Wednesday

    Wednesday: A chance of snow before noon, then a slight chance of snow after 1pm.  Mostly cloudy, with a high near 19. Northwest wind 7 to 10 mph becoming southwest in the afternoon.  Chance of precipitation is 30%. Little or no snow accumulation expected.

    Chance Snow

    High: 19 °F

  • Wednesday
    Night

    Wednesday Night: A 20 percent chance of snow.  Mostly cloudy, with a low around 11. Wind chill values as low as zero. South southwest wind around 8 mph.

    Slight Chance
    Snow

    Low: 11 °F

  • Thursday

    Thursday: Snow likely, mainly after 11am.  Mostly cloudy, with a high near 16. Wind chill values as low as -5. South southwest wind 9 to 14 mph, with gusts as high as 23 mph.  Chance of precipitation is 70%. New snow accumulation of around an inch possible.

    Snow Likely

    High: 16 °F

  • Thursday
    Night

    Thursday Night: Snow.  Low around 14. South southwest wind 10 to 13 mph, with gusts as high as 21 mph.  Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible.

    Snow

    Low: 14 °F

  • Friday

    Friday: Snow likely, mainly before 11am.  Partly sunny, with a high near 24. North northwest wind 10 to 15 mph, with gusts as high as 25 mph.  Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

    Snow Likely
    then Chance
    Snow

    High: 24 °F

  • Friday
    Night

    Friday Night: Partly cloudy, with a low around 7. North wind 10 to 13 mph, with gusts as high as 22 mph.

    Partly Cloudy

    Low: 7 °F

  • Saturday

    Saturday: Mostly sunny, with a high near 22. North wind around 11 mph becoming south southwest in the morning. Winds could gust as high as 20 mph.

    Mostly Sunny

    High: 22 °F

  • Saturday
    Night

    Saturday Night: Partly cloudy, with a low around 8.

    Partly Cloudy

    Low: 8 °F

The Last Word

As we wait for the next dump of snow, now is an excellent time to practice avalanche rescue. Are you fast and efficient with your beacon? Is your partner? Even the sharpest knife needs an occasional tune. Check out this BCA video to hone your skills.