21-22

Yale Creek out of Island Park

Date
Activity
Snowmobiling

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.

Region
Island Park
Location (from list)
Yale Creek
Observer Name
Bret Rasmussen

GNFAC Avalanche Forecast for Thu Jan 6, 2022

Snowpack and Avalanche Discussion

<p>The avalanche danger is rising. Today is snowy and windy with the bulk of the storm occurring during daylight hours. 6-12” is expected to fall and will create instabilities. Wind-loading at most elevations will make thick drifts that could break and avalanche. Additionally, there is a weak layer 6-12” under the surface on some slopes. An avalanche was seen at this depth in Lionhead that broke a day or two prior (<a href="https://www.mtavalanche.com/images/22/recent-avalanche-lionhead"><stron…;). A buried layer of faceted crystals or feathery surface hoar is the likely culprit, but the specifics don’t matter, just that a new weak layer is being loaded and avalanching. Outside Cooke City a “whumph” or collapse was felt on Henderson Mountain, a sign of instability. Today’s snow will create dangerous avalanche conditions. Triggering slides in fresh wind drifts or a deeper layer is likely. Travel carefully and do not expose yourself to steep terrain. An error in judgement could be deadly. For today, the avalanche danger is rated CONSIDERABLE on all slopes.</p>

<p>Today’s snowfall is welcome, but carries a heightened risk of avalanches. Wind speed is increasing at all elevations. It is blowing westerly at ridgelines, but will swirl and load slopes at many aspects and elevations. These wind drifts could be triggered. Furthermore, a layer of weak, faceted snow 1-3 feet deep in the Bridger Range is widespread and could avalanche as it did last week on Saddle Peak (<a href="https://www.mtavalanche.com/node/25329"><strong><u>details</u></strong>…;). Today’s snow is falling onto a relatively stable snowpack but we have concerns nonetheless. Ian was on Mt Ellis on Tuesday and took the time to test the snow before he exposed himself to avalanche terrain (<a href="https://www.youtube.com/watch?v=Zp4MIwaLaac"><strong><u>video</u></stro…;). New snow today creates instabilities with wind-loading. It also creates questions about how it is bonding to the old snow surface and how buried weak layers, some near the ground, are handling this week’s snowfall. Already 8-10” of snow (.8” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</u></a>) has incrementally loaded the snowpack since Monday. The avalanche danger is rising and due diligence is required: dig, test and only expose 1 person at a time to avalanche terrain. For today, it is possible to trigger avalanches and the danger is rated MODERATE on all slopes.&nbsp;</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out:

Avalanche near Lionhead Peak

Lionhead Ridge
Lionhead Range
Code
SS-N-R3-D2-O
Elevation
9000
Aspect
NE
Latitude
44.73280
Longitude
-111.33200
Notes

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.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

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. Photo: B. Fuglie

Lionhead Range, 2022-01-06

Bear Basin

Date
Activity
Skiing

GNFAC,
I skied partway into Bear Basin today, skiing was particularly good. 3” of new fluff was sitting on soft snow on the east side and smooth firm snow on the west side. Light winds at the ridge weren’t transporting much snow. It was overcast and not snowing the whole afternoon. I dug a quick pit on an East facing slope at 8600ft. HS was 110, “Fist” snow faded to 4F snow which sat on Fist 2-4mm facets above the ground. Definitely not a strong base, not that much different than last week when I dug in a similar spot. ECTX, soft snow just smooshed under my shovel.
Psyched on more powder skiing!
Spencer

Region
Northern Madison
Location (from list)
Bear Basin
Observer Name
Spencer Jonas

Hyalite lake

Date
Activity
Snowboarding

I took a tour up the main fork of hyalite and approached a west facing wall near hyalite lake. at around 9200 feet I dug a pit to check the snow pack
I could tell the snow pack structure was not great because while skinning up I would either sink deep into the snow pack or stay on top the wind crust
Here is what I found
Slope angle 37deg
105 snow depth
ECTP 20
Failed 25cm off ground on large grain facets
Snow structure was not good and I did not ride that slope and went back down my skin track

The wind over the past week really hammered the snow above hyalite lake

I did find good riding below the lake

Region
Northern Gallatin
Location (from list)
Hyalite - main fork

Ernest Miller Ridge

Date
Activity
Skiing

Quick snow pit at approximately 44.9556, -111.1299 (Gaia). 145 cm depth. 0 to 10 cms off ground was depth hoar, not particularly large grains. Slight crust at 125 cm from ground. ECTX (no initiation or propagation). Top 200+ vertical feet of Ernest Miller Ridge is wind slab. We skied (party of 5) lower slopes and found good skiing in slightly consolidated snow.

Region
Southern Madison
Location (from list)
Ernie Miller Ridge
Observer Name
David Combs

GNFAC Avalanche Forecast for Wed Jan 5, 2022

Snowpack and Avalanche Discussion

<p>Strong winds combined with a few inches of new snow have created thin fresh drifts that could break in small avalanches today. These will be the most obvious avalanche hazard today, but not the most worrisome. The less likely but more dangerous possibility is triggering an avalanche on the weak layers buried deeper in the snowpack. These avalanches could break 3-5 ft deep. A slide on Mount Abundance a few days ago (<a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-1"><st…;, <a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-2"><st…;) and the fatal avalanche last week on Scotch Bonnet (<a href="https://www.mtavalanche.com/accident/21/12/30"><strong><u>details</u></…;) provide sobering examples of the sort of slides that could break today. The possibility of triggering one of these slides keeps us hesitant to ride slopes steeper than 30 degrees. The avalanche danger is MODERATE today.</p>

<p>In the Bridger Range thin wind slabs could break beneath freshly drifted snow or avalanches could break deeper on a thin layer of weak, faceted snow buried 1-3 ft deep. The weak layer that has been acting up in the Bridger Range is in the middle or upper snowpack instead of near the ground. Last week’s slides on Saddle Peak show why we’re concerned about avalanches breaking on this weak layer (<a href="https://www.mtavalanche.com/node/25329"><strong><u>details</u></strong>…;, <a href="https://www.mtavalanche.com/images/22/natural-large-wind-slab-argentina…;, <a href="https://www.mtavalanche.com/images/22/natural-avalanche-saddle-peak"><s…;). This weak layer appears to be widely distributed so assume it is on every slope and plan your route according. Human triggered avalanches are possible and the avalanche danger is MODERATE.</p>

<p>Large avalanches are unlikely in the Northern Madison and Northern Gallatin Ranges. A few inches of new snow and strong winds have built thin wind slabs, but these will generally be thin enough and/or well bonded enough to not be a significant hazard. Stay on alert in case you find a slope with a thicker slab of wind drifted snow that is not well bonded. Cracks shooting out in front of your skis or snowmobile mean that you’ve found a problematic drift. Yesterday on Mt. Ellis I was finding the same generally stable snowpack we’ve seen elsewhere in the northern ranges, but I still dug a snowpit just before entering avalanche terrain as a double check to make sure I didn’t get surprised (<a href="https://www.youtube.com/watch?v=Zp4MIwaLaac"><strong><u>video</u></stro…;). Search for signs of isolated instability and be ready to adjust your plans accordingly. The avalanche danger is LOW.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out: