23-24

New snow, light-moderate wind

Date
Activity
Snowmobiling

We rode over Lulu Pass and around Fisher Peak into Abundance drainage. There was 8” of new snow that fell since Saturday, up to 12” north of Daisy. Wind was light to moderate and could see snow transport at peaks and ridgelines. Snowed most of the day with some heavy pulses, and some periods of decent visibilty.

Light was flat, but didn’t see any slab avalanches today while riding. I just spotted one small slab from town with binos on the east face of Mineral. There were a couple very small loose slides off the highest ridge of Henderson.

Region
Cooke City
Location (from list)
Lulu Pass
Observer Name
Alex Marienthal

Poor structure and test in Beehive

Date
Activity
Skiing

We skied into Beehive Basin. It was snowing lightly with calm wind. Skinning to Tyler's slope we could see wet avalanche debris from last week. We dug on the flank of Tyler's slope to look at the crust, but the snowpack was very thin and not representative of starting zones. The corniced ridge only had minimal new snow loading. As we skied up we had no collapsing. We dug in the trees on an east facing slope near the ridge, not far from all the holes the recent avalanche students made. We found 100cm of snow and got an ECTP15 on facets at the slab interface. A 5cm melt freeze crust is a nice marker from last week and Ian measured 1" of SWE above it, effectively doubling the slab depth/weight. We were in the fog on the ridge and could not get a look around.

Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
Doug Chabot

GNFAC Avalanche Forecast for Tue Feb 6, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>We are continuing an Avalanche Warning in the southern Gallatin and southern Madison Ranges, the Lionhead area and Island Park. Very dangerous avalanche conditions exist. Dave and I toured into Bacon Rind and had constant collapsing and cracking as soon as we left the car (</span></span></span></span></span></span><a href="https://youtu.be/zcBGHzPcXtw"><span><span><span><strong><span><u><span>…; and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30508"><span><span><span><strong><span…;). Little trees would shake from the collapsing waves, which is a blaring warning from Mother Nature that avalanches were imminent. Further south in Lionhead and Island Park, the new snow is deeper and slopes will avalanche. Snow bikers in Island Park had wicked collapsing on Sunday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30521"><span><span><span><strong><span…;) and since then over a foot of new snow has fallen making it even more dangerous. A person could trigger slides from flat terrain as whumpfs travel uphill. </span></span></span></span></span></span><span><span><span><span><span><u><span><span>Today is a day to avoid being on or underneath avalanche terrain</span></span></u></span></span></span></span></span><span><span><span><span><span><span>. The avalanche danger is HIGH.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Since Friday, the mountains around Bozeman, Big Sky, and Cooke City received 5-8” of new snow (0.4-0.8” of snow water equivalent). Strong southwest wind yesterday created unstable wind drifts throughout. Skiers in the Bridger Range saw natural avalanches, had collapsing around Fairy Lake and Frazier Basin and poor test scores north of Bridger Bowl (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30517"><span><span><span><strong><span…;).&nbsp; Further south in Beehive Basin, skiers on Sunday saw natural and skier-triggered loose snow slides and one slab avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30495"><span><span><span><strong><span… and details</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). In Cooke City, although the snowpack is deeper than in the northern mountains, it is showing similar signs of instability with </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30491"><span><span><span><strong><span… avalanches</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, collapses, and poor test scores (Friday’s </span></span></span></span></span></span><a href="https://youtu.be/gJtR7y1kYuU?feature=shared"><span><span><span><strong>… update video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Alex is currently there, and his two videos, </span></span></span></span></span></span><a href="https://youtube.com/shorts/c7XwPvZ93ZU?feature=share"><span><span><span… north</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> of town and the </span></span></span></span></span></span><a href="https://youtube.com/shorts/uJXOKijsY38?feature=share"><span><span><span… south</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, unequivocally show us the lurking danger.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The snowpack is very weak and unstable. We have seen avalanches every time there is a couple inches of new snow. Traveling in avalanche terrain is dangerous and it is likely you would trigger an avalanche 1-2 feet deep. Even traveling underneath steep slopes is not advised as collapses warn us that we can trigger slides from flat ground. The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>

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Many collapses in IP

Centennials - Idaho
Island Park
Code
Latitude
44.51680
Longitude
-111.63000
Notes

From FB:

We were in the centennials on 4FEB24 and felt whumping collapses on flat snow at 7500’ in the upper finger tributaries of Myers creek. 4 of us snowbiking, and some were using Voyager Pros and phone apps carefully watching slope angle and extremely wary of anything that typically we’d ride on in more stable times. I pulled up to wait for the other three in a relatively flat spot, when the next snowbike pulled up next to me I felt a drop of 2-4 inches and could hear it over the other riders engine. After he shut off I let him know. When the next ride pulled up to us it happened again I we all felt it! Th crust layer there was great for traction and seems to be about 6-10” thick over our weak faceted base layer of 2-3’. I haven’t experienced that in the past 9 seasons on the bike.
Number of slides
0
Number caught
0
Number buried
0
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Many collapses in IP

Date
Activity
Snowmobiling

From FB:

We were in the centennials on 4FEB24 and felt whumping collapses on flat snow at 7500’ in the upper finger tributaries of Myers creek. 4 of us snowbiking, and some were using Voyager Pros and phone apps carefully watching slope angle and extremely wary of anything that typically we’d ride on in more stable times. I pulled up to wait for the other three in a relatively flat spot, when the next snowbike pulled up next to me I felt a drop of 2-4 inches and could hear it over the other riders engine. After he shut off I let him know. When the next ride pulled up to us it happened again I we all felt it! Th crust layer there was great for traction and seems to be about 6-10” thick over our weak faceted base layer of 2-3’. I haven’t experienced that in the past 9 seasons on the bike.
Region
Island Park
Location (from list)
Centennials - Idaho
Observer Name
Aaron Vaughn

Collapse in Cooke

Republic Creek
Cooke City
Code
Latitude
44.98550
Longitude
-109.94100
Notes

We skied south of Cooke City and dug a snowpit at 9,761' on a west facing slope. We had an ECTP21, 40 cm below the surface (16" down). There was 6-8" of new snow from the weekend above 4" of soft old snow, on top of 4" of a pencil- hard slab, then the soft sugary facets to the ground. ECT broke below the hard slab at the top of the facets (photo). I had one collapse, 10-12' wide near treeline where there was little more wind-loading/effect (photo). 

The unstable test score, very poor snowpack structure, and collapse indicate a person could easily trigger a large avalanche on steep slopes.

Snowed lightly on and off all day with a couple cm accumulation. Wind was light-moderate out of the southwest with mostly overcast skies.

Number of slides
0
Number caught
0
Number buried
0
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Skier Triggered Loose Snow, Bridger Range

The Ramp
Bridger Range
Code
L-AS
Latitude
45.82880
Longitude
-110.93100
Notes

Skiers near the Ramp noted recent ski-triggered avalanches in steep terrain. These avalanches were isolated to the new snow and small in size. 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Skier
Problem Type
New Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year