23-24
GNFAC Avalanche Forecast for Tue Dec 12, 2023
Snowpack and Avalanche Discussion
<p><span><span><span><span><span><span>Every day over the last 5 days, somewhere in our forecast area the snowpack has either avalanched or collapsed with a “whumpf”. Our snowpack depth may vary, but its weak and unstable structure is ubiquitous. Right now, avalanches in one mountain range mean they can occur in others. In all areas, the lower part of the snowpack consists of sugary facets that are struggling to support the snow above it. Yesterday, Dave and his partner rode into Taylor Fork and found 2 avalanches, had a large whumpf as he approached his pit site, and got a very poor result in his stability test (</span></span></span></span></span></span><a href="https://youtu.be/WYftaKjgFF8"><span><span><span><strong><span><u><span>…;). Any one of these is a clear warning to stay out of avalanche terrain (slopes steeper than 30०). Yesterday, skiers on Mt. Blackmore in the northern Gallatin Range saw an avalanche, heard whumpfs and also had poor test scores, another trifecta of instability (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29489"><span><span><span><strong><span…;). Further away in Cooke City, skiers had multiple whumpfs as they toured (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29487"><span><span><span><strong><span…;). A whumpf is the sound of the snowpack collapsing from your weight; it is an avalanche on the flats. If the collapsing layer propagates onto a steep hill, it will avalanche, which is what snowmobilers experienced in Teepee Basin in the southern Madison Range on Saturday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29472"><span><span><span><strong><span…;). </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The snowpack is unstable everywhere in our forecast area. Triggering avalanches is likely and we advise staying out of avalanche terrain. Look at our </span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span… and Avalanche Log</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> to understand the breadth of the instability, and read the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><…; for more details. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Throughout our forecast area, the avalanche danger is rated CONSIDERABLE on all slopes. </span></span></span></span></span></span></p>
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2 avalanches, collapsing and ECTP3 in Taylor Fork
Date
Activity
Snowmobiling
Dave Zinn saw two avalanches, had a large collapse and an ECTP3 in his stability test.
Like the rest of the advisory area, the snowpack in the Taylor Fork is unstable and consists of a weak foundation capped by a slab of snow. Considerable danger, recent avalanches and collapsing were enough to keep us off steep slopes. Without new snow this week, you will observe fewer obvious signs of instability, but the weak structure will persist, and any steeper terrain should be approached cautiously.
Region
Southern Madison
Location (from list)
Taylor Fork
Observer Name
Dave Zinn
On 12/11, skiers noticed this recent D2 avalanche on the E aspect of Blackmore. As they skinned up the SE meadow, they experienced three audible whumpfs. Photo: Eric H
Avalanche Details: Whumpfing and avalanches on Mt. Blackmore
Forecast link: GNFAC Avalanche Forecast for Tue Dec 12, 2023
Northern Gallatin, 2023-12-12
Forecast link: GNFAC Avalanche Forecast for Tue Dec 12, 2023
Whumpfing and avalanches on Mt. Blackmore
Mt Blackmore
Northern Gallatin
Code
AS
Latitude
45.44440
Longitude
-111.00400
Notes
Toured up toward Mt. Blackmore today with the goal of skiing the mellow SE facing meadow and familiarizing myself with the current unstable snowpack. While stopping for lunch I dug a quick pit out of curiosity and performed a CT at 8757’ on a NW aspect with HS 85cm. Results were CT11 down 17 cm within the new snow on a hardness change and a CT13 down 35 cm on old facets. Moving farther up in the basin we noticed the pictured recent D2 avalanche on the E aspect of Blackmore. As we skinned up the SE meadow, we experienced three audible whumpfs. Otherwise great skiing was found today albeit a bit thin!
Number caught
0
Number buried
0
Trigger
Skier
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
Large Collapses North of Cooke City
Miller Ridge
Cooke City
Code
Latitude
45.04230
Longitude
-109.96500
Notes
Lots of collapsing today near Miller Ridge (S, SE facing slopes), just 50' from the road. This continued in more sheltered areas as well. Dug on a NE facing slope at 9300', HS: 80 ECTP12 @ 40 cm.
Number caught
0
Number buried
0
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
Whumpfing, avalanches, poor test scores Mt. Blackmore
Date
Activity
Skiing
Toured up toward Mt. Blackmore today with the goal of skiing the mellow SE facing meadow and familiarizing myself with the current unstable snowpack. While stopping for lunch I dug a quick pit out of curiosity and performed a CT at 8757’ on a NW aspect with HS 85cm. Results were CT11 down 17 cm within the new snow on a hardness change and a CT13 down 35 cm on old facets. Moving farther up in the basin we noticed the pictured recent D2 avalanche on the E aspect of Blackmore. As we skinned up the SE meadow, we experienced three audible whumpfs. Otherwise great skiing was found today albeit a bit thin!
Region
Northern Gallatin
Location (from list)
Mt Blackmore
Observer Name
Eric H
Tequila Tour (Hyalite, East Fork)
Date
Activity
Ice Climbing
I went with a party of 4 to check out the ice climb Tequila Tour - what we believe to be "Willis Route" in the guidebook. This is the next significant drainage south of Horsetail Falls on the west side of the east fork valley.
Around the base of the climb (45.43740, -110.91324), we found on an unshaded south facing aspect a snowpack of 30-40cm. Icy crust layer for the bottom 8-10cm with 4F harness and then very fluffy new snow on top.
Lower down near the creek, the snowpack is thinner - much of the recent snow and wind transported snow is up in the trees.
Today, there was a quick dump of new snow, lasting about 30 minutes. The sun came out briefly afterwards.
Our party got to the bottom of P1 and turned around. While we knew the gully between pitches is relatively low angle, we were a bit uncertain about the size and positioning of hanging snowfields above and knew that today's forecast was considerable. Something to revisit later.
Region
Northern Gallatin
Location (from list)
Hyalite - East Fork
Observer Name
Kevin Dice