Trip Planning for Island Park

as of 5:00 am
Feb 20″ |
Feb 1 2″ | NA
Jan 31 0″ | NA
9885′     02/03 at 04:00
14.3℉
S - 0mph
Gusts Unknown mph
8750′     02/03 at 03:56
81.7″ Depth
0.0″New
7710′     02/03 at 04:00
21℉
66″ Depth
Bottom Line: Avalanche conditions remain dangerous today. Wind is blowing snow and loading slopes. Weak layers in the top 3 feet of the snowpack, as well as sugary, weak snow at the ground, are still adjusting to the weight of the weekend snow and recent wind-drifting. Avoid avalanche terrain and runout zones (slopes underneath).
Primary Problem: Persistent Weak Layer

Snow Observations- Island Park

GNFAC
Lionhead Range
Lionhead Ridge
Avalanches and remote trigger
Snow Obsdrvation includes images
Snow Obs contain video

As we rode into Lionhead we saw many slides that either ran naturally or from cornice falls. Most of the slides happened Fri or Sat. Winds are blowing strong at all aspects and elevations. Slopes are being loaded further and we triggered a small slide (video) from 50 feet away (aka remotely triggered). This is a serious sign of instability and we were careful to not get on or underneath avalanche terrain.

Full Snow Observation Report
K. Allred
Island Park
Two Top
Winter storm warning
Observation Date:

January 26, 2023 - January 26, 2023 

Submitted:

January 27, 2023 

Observer:

RRS - Kevin Allred 

Zone or Region:

Island Park 

Location:

Mount Two Top (NNE 7680')

Signs of Unstable Snow

Recent Avalanches? 

 None Observed 

Cracking? 

 None Experienced 

Collapsing? 

 None Experienced 

We Traveled to the Two Top area. Due to low visibility and new drifting snow Our snow pit location was in a lower tree covered elevation. We observed a surprisingly strong snowpack void of the obvious buried SH layers we found higher. With new snow available for transport and strong SW winds we observed wind loading on NNE aspects in the area. 

Snow Stability

Stability Rating: 

Good 

Confidence in Rating: 

 Moderate 

Stability Trend: 

Worsening 

Bottom Line

The Buried SH layers are still present especially in higher elevation open slope areas. With the arrival of new snow, accompanied by strong winds the potential to form a wind slab over a PWL (Buried SH) could have serious consequence to riders in this area.

Advanced Information

Weather Summary

Cloud Cover:

Obscured 

Temperature:

15° 

Wind:

Strong , SW 

New/Recent Snowfall:

1 inch of new snow reported from the previous night. 

Winter storm warning had been issued for the area. 18'' of new snow in higher elevations followed by strong winds. We observed new snow available for transport at all elevations 

Avalanche Observations

Avalanche Observation Comments:

None observed

Snowpack Observations

NNE aspect 7680' HS 175cm CTN

Avalanche Problems

Heightened awareness of increasing avalanche danger with the arrival of this storm.

Terrain Use

Our travel mindset for the day, to not travel in avalanche terrain over 30°.Due to low visibility, blowing and drifting snow our travel plan was impacted and our route was shortened. I learned later of 2 riders in the Keg springs area that dropped into Carrot canyon unable to get out due to a damaged Snowmobile they where rescued by Clark county SAR 03:30 this morning. All where cold tired but SAFE! A big thanks to Clark County SAR A reminder of the dangers of back country travel

Full Snow Observation Report
K. Allred
Island Park
Two Top
Buried Surface Hoar layers near Two Top

Signs of Unstable Snow

Recent Avalanches? 

 None Observed 

Cracking? 

 None Experienced 

Collapsing? 

 None Experienced 

We observed a strong cohesive snowpack on a wind loaded slope NE of Two Top. But we noticed three separate buried SH layers. First 5cm from surface second @ 25cm third @55cm. These buried SH layers tend to be touchy. They are concerning in that the deeper layers rest above and below densely packed wind blown slab.

Three separate layers of Buried SH within the top 100cm of the snow pack. The top layer @5cm from the surface is not worrisome at this time but with added snow in the future it has potential to become a problem layer. The second and third layer @25cm,@55cm,from surface could be human triggered, with the potential of a deadly slab avalanche.

Advanced Information

Weather Summary

Cloud Cover:

Partly Cloudy 

Temperature:

17° 

Wind:

Light , SW 

New/Recent Snowfall:

No resent snow 

Upper elevations mostly sunny the past 2 days.Lower elevations experienced AM fog Light winds. We noticed ridge top blowing snow.

Advanced Information

Weather Summary

Cloud Cover:

Partly Cloudy 

Temperature:

17° 

Wind:

Light , SW 

New/Recent Snowfall:

 

Avalanche Observations

Avalanche Observation Comments:

Observed several natural avalanches on NE ridge at Two Top below cornice in steep wind loaded terrain

Snowpack Observations

NNE aspect 8186ft, 44.62319,-111.24732, HS230,PWL buried SH@ 5cm,25cm,55cm from surface. First test, CTMsc@55 second test CTMsc@25. ECTN27@25 

layer of SH,@ 55cm below surface

Layer Depth/Date: Jan.22,2023  
Weak Layer(s):  Jan 5, 2023 (SH) 
Comments: Buried SH 5,25, 55, CTMsc@55, CTMsc@25 ECTN 27@ 25

Buried layers of SH. These layer's seem to be very widespread throughout the region. They are worrisome in that they could be human triggerd with deadly potential.

Terrain Use

Our travel Plan to avoid any terrain greater than 30°. There are many options in this area to have a challenging ride without exposing the group to avalanche hazard.

 

Full Snow Observation Report
K. Allred
Island Park
Yale Creek
Test

Observation Details

 

 

Observation Date:

January 21, 2023 - January 21, 2023 

Submitted:

January 21, 2023 

Observer:

RRS - Kevin Allred 

Zone or Region:

Island Park 

Location:

Yale Creek (SSW) 

Signs of Unstable Snow

Recent Avalanches? 

 None Observed 

Cracking? 

 None Experienced 

Collapsing? 

 None Experienced 

Found a layer of near surface facets 25 cm from the surface not problematic now but with new snow coming this could become a layer of concern 

Snow Stability

Stability Rating: 

Good 

Confidence in Rating: 

 Moderate 

Stability Trend: 

Steady 

Bottom Line

The snow seems to be very stable found a MF crust 45cm / surface from a warming trend early in January. Below the MF layer a strong cohesive slab. 15cm layer of DH at ground level average grain size of 2 mm 

Advanced Information

Weather Summary

Cloud Cover:

Clear 

Temperature:

17º 

Wind:

Calm , SW 

New/Recent Snowfall:

Trace of new snow past 24 hours 

Mostly clear skies light winds out of the south west no blowing snow 

Avalanche Observations

Avalanche Observation Comments:

None Observed

Snowpack Observations

Head of Yale Creek 8470' elevation SSW aspect HS 175 CTM SC @ 20 cm below surface on a near surface FC. ECTN 

Avalanche Problems

Our primary concern is a layer of SH that is variable in distribution . This layer was not evident in our snow pit location. 

Terrain Use

Our travel plan avoid avalanche terrain over 30° We traveled to observe an avalanche fatality site from 1998. The area had heavily trafficked by snowmobile activity. We remained with our conservative travel plan at 30°

Full Snow Observation Report
B. Rasmussen
Island Park
Centennials - Idaho
buried surface hoar
Snow Obs contain video

We are finding impressively strong snowpack. But we also have a weak layer buried about 2 feet into the snowpack that is very worrisome. It's deep enough that when triggered will be deadly, consider consequences and know where the persistent weak layer is before exposing your group. We have been on the snow all week and find lots of powder to play in without using slopes and connected terrain that is greater than 30 degrees.

SE aspect, 7640 ft, HS 130, PWL buried SH 83, DH 45, CTHsc@83, ECTN23@45. 

This PWL is widespread, but not necessarily reactive in all areas. We did feel a collapse on this same aspect and elevation yesterday, near Sawtelle Creek so we went back to test and found some results. 

Full Snow Observation Report
B. Rasmussen
Island Park
Sawtelle Peak
Whumpf near Sawtelle Peak

I dug one pit at 8200’ NE aspect in Yale ECTX. Kevin was a little lower and around on the east side of Sawtell, he felt a big wumph. He didn’t confirm what layer, but this is probably your buried SH.

Full Snow Observation Report
Anonymous
Lionhead Range
Two Top
Small avalanche off Two top, west Yellowstone
Snow Obsdrvation includes images

Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown.

Full Snow Observation Report
GNFAC
Lionhead Range
LIONHEAD AREA
Natural and sledder triggered slides, Lionhead
Snow Obsdrvation includes images
Snow Obs contain video

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

Full Snow Observation Report
RRS
Island Park
Sawtelle Peak
Sawtelle obs

Wind loading from last storm snow. Large surface hoar formed on all aspects. Also noticed 1-2cm settlement around trees on northeast facing slopes.

Full Snow Observation Report
GNFAC
Island Park
Arange Peak
Hunting for weak layers
Snow Obsdrvation includes images
Snow Obs contain video

We rode to Arange Peak and dug a pit (HS 210 cm, S facing, 8800'). We found the SH/nsf layer, but it did not propagate, It was a good 2 feet under the surface. We then rode and dug 3 more quick pits and either didn’t find the SH or had ECTN or CTN. We saw no avalanches and a rider who was near Mt. Jefferson 2 days ago also saw no activity. I am still very leery of the SH and believe it survived on a few slopes and acted accordingly, i.e. no riding steep slopes.

Full Snow Observation Report
GNFAC
Lionhead Range
LIONHEAD AREA
Natural and sledder triggered slides, Lionhead
Snow Obsdrvation includes images
Snow Obs contain video

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

Full Snow Observation Report
RRS
Island Park
Sawtelle Peak
Sawtelle obs

New snow and wind loading. On southeast facing slopes found 8cm layer of facets below melt freeze layer about 50-60cm below surface.

Full Snow Observation Report
Anonymous
Island Park
CENTENNIAL RANGE
two top trail

side hilled off of two top trail and broke small slab off

Full Snow Observation Report
High Mtn Adventure
Island Park
Mt Jefferson Bowl
Snowmobiler Triggered slide Island Park
Snow Obsdrvation includes images

From Facebook: High Mountain Adventures snowmobile rental reported one of their renters triggered a slide on the waterfalls (Mt Jefferson/Sawtelle).

Full Snow Observation Report
B. Rasmussen
Island Park
Sawtelle Peak
snowpack is becoming stronger
Snow Obsdrvation includes images

I am finding very solid snowpack in most areas. We dug one pit yesterday that exhibited two weak layers in the top 35cm and one near the ground. This was a wind loaded slope with HN 230cm. CT test did not fail. No evidence of surface hoar at this location. 9100 feet on a NE aspect.
At lower elevations I found evidence of surface hoar forming, but not necessarily on the snow, see photo.

We are entering a warming trend, which is generally healthy for the snowpack. The conditions are right for surface hoar development; however, I am only finding very isolated evidence of this. Something to keep an eye out for.

We have several weak layers in the snowpack that could fail causing an avalanche, likely a large deadly avalanche. It's hard to find places that exhibit reactive test results, but the evidence is in recently human triggered avalanches. We are not getting a ton of new snow and together with the mild temperatures this will create a strong snowpack over time. The places to watch out for are shallower snowpack areas where the persistent weak layer is easier to trigger.  

Full Snow Observation Report
D. Trainor
Island Park
Centennials - Montana
Pit in Island Park
Snow Obsdrvation includes images

From IG 1/7/23: We dug a pit in island park back up Blue Creek on the Centennials side. South facing slope. ECTX

Full Snow Observation Report
C. Rasmussen
Island Park
Sawtelle Peak
Column

Same PWL's as observed in recent past. Newly forming wind slabs and a more recently formed 2 cm (very fragile) melt freeze crust at 228 cm. 

4-5 in. HST on top of melt freeze crust

A lot of blowing and lightly falling snow the past few days. Larger drifts forming on the NE aspect ridge line where we dug our test pit today.

CTH 192 cm above melt freeze crust

Full Snow Observation Report
Brian
Island Park
Island Park Taylor Creek
Snow Obsdrvation includes images

Extremely crusty snow. Dug a pit and found three very defined ice layers around 5500ft. 

Full Snow Observation Report
C. Rasmussen
Island Park
Two Top
Near Two Top

Newly formed melt freeze crust near surface and wind slab continuing to form due to current weather conditions. Wind loaded slopes will continue to be a hazard along with PWL's.

Full Snow Observation Report
Andrew
Island Park
Yale Creek
whumpf under high load on south side of Taylor mountain.

Had 7 sleds in a relatively small area on the south facing side of Taylor mountain at about 10k ft.

Group noticed a substantial wumph after sitting for less than a minute.

Don't believe it is cause for serious alarm as a snow pit showed relative stability. Just something we all noticed and talked about and to be aware of as the snow continues to fall.

 

1/3/23

Full Snow Observation Report

Relevant Avalanche Activity

Island Park
Sawtelle Peak
Whumpf near Sawtelle Peak
Sawtelle Peak
Coordinates: 44.5611, -111.4430
Caught: 0 ; Buried: 0

I dug one pit at 8200’ NE aspect in Yale ECTX. Kevin was a little lower and around on the east side of Sawtell, he felt a big wumph. He didn’t confirm what layer, but this is probably your buried SH.


More Avalanche Details
Lionhead Range
Two Top
Small avalanche off Two Top
Incident details include images
Two Top
SS-AMu-R1-D1-I
Coordinates: 44.6249, -111.2590
Caught: 0 ; Buried: 0

Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown. 


More Avalanche Details

Relevant Photos

Displaying 1 - 26
  • Surface hoar can often be seen as a grey stripe on the wall of your snowpit as was the case at Bacon Rind in the Southern Madison Range on 1/23. Photo: GNFAC

  • Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown. 
     

  • Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown. 

  • Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown. 
     

     

  • Digging a pit near East Hotel Creek in Island Park where we found a layer of surface hoar buried two feet deep. Photo: GNFAC

  • On a Jan. 16 tour into Beehive, we found the concerning layer of feathery surface hoar buried under 6" of snow. It is widespread from Big Sky through West Yellowstone and Cooke City. It has produced avalanches near Hebgen Lake, with more snow, it will likely produce avalanches in Beehive too. Photo: GNFAC

  • Snowmobile triggered avalanche in Island Park near Mt Jefferson/Sawtelle Peak. Photo: Anon

  • Skier unintentionally triggered and was caught in wind slab avalanche on the Y couloir in Sheep Creek Drainage. Skier was carried 10m before self arresting. The slide ran ~250m down and broke across the entire width of the couloir. There were no injuries and skied away. 

  • We looked at the avalanche that killed a snowmobiler yesterday (12/31/22) on Crown Butte near Cooke City. Our deepest condolences go out to the family and friends of the victim, and those involved with the rescue and recovery. Photo: GNFAC

  • On December 31, 2022 a snowmobiler was killed in a very large avalanche north of Cooke City, MT. The avalanche occurred near Daisy Pass on Crown Butte on a southeast facing slope at 9,800’. The avalanche appeared to be 2-4' deep, 500' wide, 600' vertical, and broke on weak snow near the bottom of the snowpack. Photo: GNFAC

  • Many slick roofs shed this winter's snow with the above-freezing temperatures. There are some impressive fracture lines at the ice rink in Bogert Park in Bozeman. Photo: GNFAC

  • Alex Marienthal cuts a column for his stability test on Ski Hill in Lionhead. Photo: GNFAC

  • Alex Marienthal points a 5 cm thick weak layer of faceted snow that broke with an ECTP10. Photo: GNFAC

  • This Beacon Checker was installed by the Hebgen District FS snow rangers at the trailhead to Denny Creek and Lionhead Ridge. It was made possible by the family of Bradie Becker in partnership with The Friends of GNFAC. Bradie was killed in an avalanche on Lionhead Ridge on February 6th, 2022. Photo: J. Norlander

  • We dug a pit at 9,000 feet on a SE facing slope above Hebgen Lake. We found weak snow under a slab that broke with an ECTP26. Photo: GNFAC

  • From IG 12/3: "It was natural. Happened last night or this morning. It hadn't slid when we left yesterday. We were first tracks in today, and there were no tracks above or below this slide. Crown at the peak was around 6'. Average 2-3' crown. 10' debris piles at least." Photo: R. Malmstrom

  • From IG 12/3: "It was natural. Happened last night or this morning. It hadn't slid when we left yesterday. We were first tracks in today, and there were no tracks above or below this slide. Crown at the peak was around 6'. Average 2-3' crown. 10' debris piles at least." Photo: R. Malmstrom

  • A snowmobiler noted cracking of the snow surface on the south face of Reas Peak out of Island Park. The wind crust was 3-4" thick and had facets underneath which aided the propagation. Photo: Anonymous

  • Big Sky ski patrol triggered these slides with explosives on 11/22 during routine avalanche mitigation work. The avalanches were hard slabs that averaged 12" deep and broke on a weak layer above a crust on top of snow that fell in October. Photo: BSSP

  • Big Sky ski patrol triggered these slides with explosives on 11/22 during routine avalanche mitigation work. The avalanches were hard slabs that averaged 12" deep and broke on a weak layer above a crust on top of snow that fell in October. Photo: BSSP

  • Rimed weather station on Sawtelle Peak. 11/17/22. Photo: GNFAC

  • Observer reported "A number of Avalanche Crowns on an east aspect at 9500 ft." in Tepee Basin.

  • An observer reported "A number of Avalanche Crowns on an east aspect at 9500 ft." in Tepee Basin

  • Evidence of wind-loading creating the conditions for avalanches in the Bridger Range. Cracking is an indicator of instability. The observer noted this was "Nothing consequential," but this shows that unstable drifts are forming. They will be more consequential where there is more snow and as the wind creates larger drifts. Photo: E Smith

  • We completed the setup of a SNOdar snow depth sensor on Sawtelle Peak in the Centennials on Wednesday 10/19. Forecaster Ian Hoyer for scale.

    Located at 8800 feet elevation. The sensor will record total snow depth and 24 hr snowfall. Data will be displayed on our website soon at: http://www.mtavalanche.com/weather/stations/sawtelle-snow.

  • The newly installed Sawtelle Peak weather station. Photo: GNFAC (10/4/2022)