21-22

Skier triggered slough on Black Mtn (Absarokas)

Black Mountain
Out of Advisory Area
Code
L-AS-R2-D1.5
Latitude
45.16280
Longitude
-111.52900
Notes

Observation from the Y-couloir on Black Mountain in the Absarokas (outside of the advisory area) 4/1/22:

"Crown was 4-6” deep, approximately 30’ across (just shy of the width of the coulocouloirn the length of the coulocouloir0’). Layer that slid consisted of new, unconsolidated snow. The slide was sslidetriggered, skier stayed on his feet as it ran by them. We dug a pit beforehand on a similar aspect and goaspectN. New snow concerns matched that of the forecast for today."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Skier
R size
2
D size
1.5
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

GNFAC Avalanche Forecast for Sat Apr 2, 2022

Snowpack and Avalanche Discussion

<p>Large avalanches are unlikely today. The chief concern to watch for is where this week’s new snow has been blown into deeper drifts. Look for cracks shooting out in front of your skis or snowmobile as a sign that you’ve found one of these drifts where you could trigger an avalanche. The deeper the drift, the larger resulting slide would be. Even a small avalanche can be dangerous in the wrong terrain, so be very mindful of the hazards lurking below you (trees, rocks, cliffs, etc).&nbsp;</p>

<p>While temperatures are going to rise well above freezing today, clouds should move in before wet snow becomes much of an issue. A dusting of snow this afternoon won’t do much to affect either the riding conditions or the avalanche conditions. If precipitation does start as rain, or sunshine sticks around longer than expected, watch for the surface snow becoming wet as this means you’ll soon be able to trigger small loose wet avalanches on steep slopes. If it gets wet more than a few inches deep, move off steep slopes.</p>

<p>While unlikely, it’s also not impossible to trigger a dangerous avalanche today on deeper weak layers&nbsp; (<a href="https://www.youtube.com/watch?v=0w18Fxp-dmI"><strong><u>Flanders video</u></strong></a>). Cover your bases by going one at a time on steep slopes, watching your partners from a safe spot, and always carrying your avalanche rescue gear (avalanche beacon, shovel, probe).</p>

<p>The avalanche danger is LOW today.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>&nbsp;</p>

Two natural slab avalanches in Sheep Crk, Cooke

Sheep Creek
Cooke City
Code
HS-N-R2-D2-O
Elevation
9800
Aspect Range
W, SW
Latitude
45.03440
Longitude
-109.98400
Notes

On 3/25/22 skier observed two natural slabs on a W-SW aaspectoff Miller Ridge at around 9800'.

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
24.0 inches
Vertical Fall
400ft
Slab Width
300.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Natural slab avalanches in Sheep Creek north of Cooke City. These crowns were first observed the morning of 3/25/22 and likely occurred on 3/24. Photo from 3/30/22, GNFAC

Cooke City, 2022-04-01

GNFAC Avalanche Forecast for Fri Apr 1, 2022

Snowpack and Avalanche Discussion

<p>The primary concern today is avalanches breaking where the 5” of new snow has been blown into deeper drifts by northwest winds. Look out for and steer clear of these drifts to avoid the hazard. Watch for cracks shooting out in front of your skis or snowmobile as a sign that you’ve stumbled into a drift and back off steep slopes. Loose snow slides are also possible on sunny slopes. Today these will only involve the new snow, but could run long distances on firm crusts. It’s unlikely you’ll trigger an avalanche breaking deeper, but there are still weak layers lurking on higher and shadier slopes so it’s worth keeping the possibility in the back of your mind (<a href="https://www.youtube.com/watch?v=WpfhtKv_4yQ"><strong><u>Woody Ridge avalanche video</u></strong></a>).</p>

<p>The avalanche danger is MODERATE today on windloaded slopes. On other slopes the danger is LOW.</p>

<p>Avalanches more than a few inches deep are unlikely. It’ll be possible to trigger very thin wind slabs and thin loose snow slides of the new snow heating up in the sun today, but they will generally be small and only worrisome in the most high consequence terrain. Keep an eye out in case you find a drift of windblown snow more than a few inches deep or a low elevation slope that remains wet and unsupportable. Be especially heads up in terrain where getting knocked off your feet by a small slide would have big consequences. If it gets hotter and stays sunnier than expected this afternoon, be on alert for crusts breaking down as this would mean you may be able to trigger a larger wet snow avalanche.&nbsp;</p>

<p>Yesterday Dave was in Hyalite pulling the weather station. He stopped to dig and test the snowpack before skiing avalanche terrain, got surprisingly unstable snowpack results (ECTP11) and chose a conservative exit from the area through dense trees (<a href="https://www.youtube.com/watch?v=0w18Fxp-dmI"><strong><u>video</u></stro…;). This is your reminder that LOW danger does not mean NO danger. It’s always worth checking to make sure you haven’t found the isolated slope where it is still possible to trigger a deeper slide. Use safe travel practices to cover your bases in case you do get surprised - always carry rescue gear (avalanche beacon, shovel, &amp; probe), go one at a time on steep slopes, and watch your partners from a safe spot.&nbsp;</p>

<p>The avalanche danger is LOW today.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>

GNFAC Avalanche Forecast for Thu Mar 31, 2022

Snowpack and Avalanche Discussion

<p>Temperatures are below freezing and skies will remain cloudy, effectively shutting down melting and wet avalanche activity. The snow that is falling will total a few inches and may slide as loose sluffs on steep slopes. However, the main concern is not avalanches, but ski injuries from the new snow covering up the frozen surface, described as skiing on a coral reef.&nbsp;</p>

<p>In the last week the snowpack has changed. Meltwater has percolated into layers and many slopes have moist, mushy snow. The buried layers, even dry ones, are warming and getting close to zero degrees Celsius. At this temperature liquid water moves through the snowpack and weakens it quickly. We see this when we sink to our waist in wet snow after stepping out of our skis or off our snowmobile. Today a firm ice crust will keep us from sinking. Our three most recent videos outline what to expect and how to deal with these rapidly changing springtime conditions:</p>

<ol>
<li><a href="https://youtu.be/SIsIH_mGe-E"><u>Explaining Wet, Isothermal Snow</u></a></li>
<li><a href="https://youtu.be/8LbaFYKHIvE"><u>Overnight freeze = stable in the morning</u></a>.&nbsp;</li>
<li><a href="https://youtu.be/O5K_gNFeBt8"><u>It Finally Froze in Beehive Basin</u></a></li>
</ol>

<p>Throughout our forecast area avalanches are unlikely and conditions are generally safe. Even with good stability, standard protocols apply: travel with a partner, only expose 1 person a time in avalanche terrain and carry rescue gear. Today the avalanche danger is rated LOW. If the weather forecast is wrong and the sun pokes out, slopes will get wet quickly and the danger will rise.&nbsp;</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>