20-21

Whumpfs and cracks in Specimen Creek

Specimen Creek
Southern Gallatin
Code
Elevation
7500
Latitude
45.02650
Longitude
-111.04800
Notes

S2 snow most of the day. Light winds, overcast. Extensive large whumpfs and cracks at about 7000-7800 feet. Snow was unsupportable in many places, others had a clear slab in the midpack you could feel with a pole probe . Dug a pit at 7500 ft on east aspect ...Bottom 30cm was large facets bordering on depth hoar . Clear cups forming and 3-4mm or so (F). CT18. ECTX, which surprised me... I should have done a second test. Was able to propagate on the depth hoar using a snow saw easily, though did not perform full PST.

Number of slides
1
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
20-21

A 100’ wide by 12”-24” deep avalanche was triggered by a skier on a North East aspect of Woody Ridge at 9000’. Skier was carried and partially buried after arresting on a tree. Photo: Anon

Avalanche Details: Skier triggered and partially buried on Woody Ridge
Forecast link: GNFAC Avalanche Forecast for Sat Feb 6, 2021
Cooke City, 2021-02-05
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    • Skier triggered and partially buried on Woody Ridge

    Woody Ridge
    Cooke City
    Code
    SS-ASu-R2-D2-I
    Elevation
    9000
    Aspect
    NE
    Latitude
    44.97390
    Longitude
    -109.92400
    Notes

    A 100’ wide by 12”-24” deep avalanche was triggered by a skier on a North East aspect aspect ody Ridge at 9000’. From reporting group: "Skier was carried and partially buried after arresting on a tree. The area was short pitches with rollovers and pillow/shelf features. Once the skier was in avalanche terrain the wind loaded storm slab rel slab d exposing a faceted layer which the new snow had not bound with. The release occurred where the slope went from 20 degrees to 30 degree terrain. A pit dug the previous day (2/4/2020) on the same slope resulted in an ECT 50 + and a CT 38. Afterward that day we proceeded up the ridge to find wind slabs formed at the top of the ridge which would release when cut. Today, the snow felt stable on the ascent through trees and on tree covered ridges. When we turned around in what we considered “mellow”/“putt putt” terrain due to an intensifying storm and the day becoming late we skied through some exposed ridges and drops. First skier saw no avalanche activity through broken up terrain. Second skier triggered the slide on the fir slide rn. After the event a third skier skied the tree covered ridge used for the ascent and was clear. Whompfing was observed in the trees below the pillows after the event..."

    Number of slides
    1
    Number caught
    1
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Skier
    Trigger Modifier
    u-An unintentional release
    R size
    2
    D size
    2
    Bed Surface
    I - Interface between new and old snow
    Problem Type
    New Snow
    Slab Thickness
    18.0 inches
    Slab Width
    100.00ft
    Images
    Skier triggered and partially buried on Woody Ridge
    Slab Thickness units
    inches
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    20-21

    GNFAC Avalanche Forecast for Fri Feb 5, 2021

    Snowpack and Avalanche Discussion

    <p>In the Bridger Range, the combination of 16" of new snow (1.3” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</u></a>), strong winds, and an unusually weak snowpack make for very dangerous avalanche conditions. Avalanches will break both beneath the new snow and also on weak layers mid-pack or near the ground. It is snowing heavily and more snowfall today will continue to push the snowpack past its breaking point. Conditions aren’t complicated, they are simply dangerous. Give yourself a wide safety margin while avoiding steep slopes and the runouts beneath them. Human triggered and natural avalanches are likely. The avalanche danger is HIGH on all slopes.</p>

    <p>Last night’s 3-7” of new snow (0.3-0.4” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…;) is falling onto a weak snowpack that was already stressed by the snow that has accumulated since Wednesday. Yesterday’s smaller snowfall totals may double by this afternoon. Human triggered avalanches are likely, breaking 2-4 ft deep on weak layers in the middle of the snowpack or near the ground. Yesterday in Beehive Basin, Dave and I had unstable test results on the mid-pack facets, with more loading they will only be more reactive today (<a href="https://www.youtube.com/watch?v=FTF0x_PqCfI"><strong><u>video</u></stro…;). The long list of large avalanches that broke following last weekend’s snowfall provide good examples of the sort of slides that will be easily triggered today (<a href="https://www.mtavalanche.com/avalanche-activity"><strong><u>full list here</u></strong></a>, <a href="https://youtu.be/CI0HFvtLrf4"><strong><u>Lionhead video</u></strong></a>, <a href="https://youtu.be/dVWv0RA9WMM"><strong><u>Ernie Miller video</u></strong></a>). Avalanches may break remarkably wide or be triggered from a distance. The avalanche danger is CONSIDERABLE in the Gallatin and Madison Ranges.</p>

    <p>&nbsp;</p>

    <p>With 3” of new snow and a somewhat less weak snowpack, conditions won’t be quite as touchy around Cooke City. However, there are weak layers in the snowpack and triggering an avalanche is a very real possibility. Watch for signs of instability such as cracking, collapsing or fresh avalanches and dig down to look for reactive weak layers before getting onto steep slopes. For today the avalanche danger is rated MODERATE.</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>

    <p>&nbsp;</p>

    King and Queen Fundraiser

    February 6th and 7th -- AWESOME PRIZES for individuals who raise over $500! Two pairs of skis, Airbag Avy pack, and more! Deadline for fundraising is 1:15 p.m. Sunday, Feb. 7. No racing is necessary to compete for the fundraising prizes. Info is HERE.

    GNFAC Avalanche Forecast for Thu Feb 4, 2021

    Snowpack and Avalanche Discussion

    <p>In the mountains surrounding Bozeman, last night’s 4-6” of new snow (measuring .3-.5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</u></a>-SWE) and gusty west to northwest wind will keep the potential for triggering avalanches alive and well. The new snow will be blown into drifts which will likely crack and avalanche on steep slopes. Additionally, in the last 36 hours almost 1 inch of SWE has fallen, which is a decent amount of weight to put on a snowpack that has poor structure and is seen as untrustworthy. Ian was in the Bridger Range on Tuesday and found a thin, weak, faceted snowpack (<a href="https://youtu.be/js1BXvovZ4I"><strong><u>Throne video</u></strong></a>). Skiers on Mt. Blackmore yesterday found the new snow bonding well to the old, but the sugary facets at the ground are still concerning. Stay clear of avalanche terrain; the snowpack is under new stress from the new snow and wind-loading. Triggering avalanches is likely. For today the avalanche danger is rated CONSIDERABLE on all slopes.</p>

    <p>Last night a few inches fell around Big Sky while most of the snowfall arrived yesterday morning near West Yellowstone and Cooke City. In general, the weight of new snow (.5-.7” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…; in 36 hours) and wind-loading makes it possible to trigger slides today, but it is not a sure thing. That makes navigation a bit tricky. Many avalanches last weekend (<a href="https://www.mtavalanche.com/avalanche-activity"><strong><u>full list here</u></strong></a>, <a href="https://youtu.be/CI0HFvtLrf4"><strong><u>Lionhead video of major avalanche cycle</u></strong></a>) and a snowmobile triggered slide on Monday at Lionhead (<a href="https://www.mtavalanche.com/node/24049"><strong><u>details</u></strong>…;) broke on weak layers near the ground (sugary facets) or midpack (2’ from the surface). Noteworthy slides include a very large skier-triggered avalanche on Ernie Miller Ridge near Bacon Rind on Saturday (<a href="https://youtu.be/dVWv0RA9WMM"><strong><u>video</u></strong></a&gt;, <a href="https://www.mtavalanche.com/node/23991"><strong><u>details</u></strong>…;) and another <a href="https://www.mtavalanche.com/node/24021"><strong><u>large avalanche on the Fin</u></strong></a> outside Cooke City. Avalanches will be more difficult to trigger after last week’s wallop, but two things should be considered: first, the faceted (sugary) weak layers that the avalanches broke on are still&nbsp;</p>

    <p>there, and second, the new snow and wind-loading has added weight that will keep these layers from becoming dormant. Avoid avalanche terrain entirely if you see signs of instability such as cracking, collapsing or fresh avalanches. For today the avalanche danger is rated MODERATE.</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>

    King and Queen Fundraiser

    February 6th and 7th -- AWESOME PRIZES for individuals who raise over $500! Two pairs of skis, Airbag Avy pack, and more! Deadline for fundraising is 1:15 p.m. Sunday, Feb. 7. No racing is necessary to compete for the fundraising prizes. Info is HERE.

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