23-24

Portal Creek Meadows Winds

Date
Activity
Snowmobiling
Ice Climbing

We rode portal creek meadows as an exploratory mission as neither Kyle Marvinney nor myself had ventured there much. New snow from the previous storm cycle had settled to about 4 inches, but it was hard to tell due to widespread wind effect. Judging from the snow, temps up there have mostly stayed below freezing during this previous warm cycle (after Monday/Tuesday storm), though there is fairly supportable crust below the storm layer. winds were blowing consistently 10mph up high gusting to and estimated 25mph. We observed one small avalanche in the riding area that occurred before the recent storm cycle and seemed characteristic of other similarly sized avalanches we have been observing throughout the season.

Region
Northern Gallatin
Location (from list)
Portal Creek
Observer Name
Alexander Jett

Several Recent Avalanches at Lionhead

Date
Activity
Snowmobiling

We rode into Lionhead with the USGS and USFS snow chemistry, hydrology and soil science teams. At the top of Ski Hill we dug a snow pit and in stability tests we got an ECPT27, that failed on weak snow near the ground. 
From here we rode to Motor Hill via Denny Creek. While crossing below Lionhead Ridge we saw an avalanche in Airplane Bowl that likely happened a few days ago. This avalanche broke 12” deep and 100’ wide. 
Above Motor Hill we dug another snow pit on an easterly aspect at 8600’. We had unremarkable test scores of ECTX (twice) and a PST 63/100 end. We saw a similarly poor structure as our previous pit, with weak sugary snow low in the snowpack. 
This morning with better visibility we stopped at the Hebgin pull out and were able to see 3 recent avalanches along Lionhead Ridge that were likely the result of recent wind blown snow. 

Our snow pit results above and the lack of deep avalanche activity were encouraging and initiating failure is becoming more difficult. This will change with incoming snow and wind so expect the avalanche danger to increase. This storm will hopefully test the snowpack and we are curious to see if it results in widespread avalanches or is able to support the new and wind drifted snow. 

 

Region
Lionhead Range
Location (from list)
Lionhead Ridge
Observer Name
Zach Peterson

Windslabs Republic

Date
Activity
Skiing

Toured up Republic Creek today. Went to the ridge below Republic Mountain and then to Woody Ridge. 
 

winds picked up throughout the day and by afternoon were moderate gusting to strong at treeline and ridge tops from the W,SW.

started lightly snowing around 1 pm. 

observed 2 crowns in wind loaded terrain. One at the end of Woody ridge on a north facing sub ridge (Peterson’s prow ) and the other on an East facing Ridge seen from the top of Wyoming bowl. 

Region
Cooke City
Location (from list)
Republic Creek
Observer Name
Gloria Roe

Still whumphing at Lo Elevation

Date
Activity
Skiing

Touring from 6800' - 8800'  breakable crust - both directions! Lots of whumphing down low but then none above 84-8600'.  

Region
Out of Advisory Area
Observer Name
Traute Parrie

GNFAC Avalanche Forecast for Thu Feb 29, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Yesterday, near Mt. Blackmore in Hyalite, skiers saw fresh avalanche debris near the trail. It was likely from a wind-loaded slope at low elevation, indicative of the instability that would be found higher (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31054"><span><span><span><strong><span…; and </span></span></span></span></span></span><a href="https://youtube.com/shorts/Iacb0_ScqzQ?feature=share"><span><span><span…;). A skier also had collapsing and cracking as he toured above the reservoir (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31062"><span><span><span><strong><span…;). Throughout the forecast area wind is blowing at all elevations and scraping away the fresh snow into thick drifts which are dangerous and could be triggered. The snowpack remains unstable and avalanches were seen on Buck Ridge, Taylor Fork, Lionhead and Cooke City in the last week (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span…;). The weight of recent wind drifts are making slopes unstable. In Taylor Fork on Tuesday we warned of new snow and wind creating instability, which is still true today (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31041"><span><span><span><strong><span…; and </span></span></span></span></span></span><a href="https://youtube.com/shorts/IEE7EHJTjRo?feature=share"><span><span><span…;

<p><span><span><span><span><span><span>Dangerous avalanche conditions can be found on all slopes, wind-loaded or not. A person is likely to trigger a slide if they get into avalanche terrain. Even small slopes can avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/wind-slab-n-long-lake"><span><spa…;) and these point to instability that can be found on bigger slopes (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/avalanche-n-scotch-bonnet"><span>…;). Alex’s field days in Cooke City bear this out. He found wind-loading and heaps of weak snow (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=WTcr7DstJ9Y"><span><span><span><strong>…;), which is a similar story to all the mountain ranges from Bozeman to Big Sky to West Yellowstone, Island Park and Cooke City. These mountains have a CONSIDERABLE avalanche danger on all slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Powerful wind is blowing at the ridgetops and mid-mountain elevations in the Bridger Range. Most new snow has already been scoured into drifts, but these strong winds will scrape every last flake (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/wind-scouring-bridger-peak"><span…;). Wind-loaded slopes are dangerous. Yesterday Dave saw an avalanche that occurred on Saddle Peak from wind-loading (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/wind-slab-avalanche-quarter-saddl…;), and Ian and I could see plumes of swirly snow being deposited north of the Ramp. Expect to find thick wind drifts in gullies and slopes below cornices. These could be easily triggered. Our 5’ deep snowpit showed signs of strengthening which gave us a tiny glimmer of hope, but I am still skeptical (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31052"><span><span><span><strong><span…; and </span></span></span></span></span></span><a href="https://youtube.com/shorts/kKSAXaFs2BQ?feature=share"><span><span><span…;

<p><span><span><span><span><span><span>Avoid wind-loaded slopes today since these have a CONSIDERABLE avalanche danger. Slopes without a wind-load will have a MODERATE danger.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

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Whumphs and Cracking in Hyalite

Hyalite - main fork
Northern Gallatin
Code
Latitude
45.44720
Longitude
-110.96200
Notes

Skiing some dog pow across Hyalite reservoir between 7200-7800’ on a NE pitch I got lots of whumphs and shooting cracks while braking trail. This was a shallower snowpack than most other areas, it was still easy to break into basil facets with skis on.

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

Skiing some dog pow across Hyalite reservoir between 7200-7800’ on a NE pitch I got lots of whumphs and shooting cracks while braking trail. This was a shallower snowpack than most other areas, it was still easy to break into basil facets with skis on.

Northern Gallatin, 2024-02-29

Whumphs in Hyalite

Date
Activity
Skiing

Skiing some dog pow across Hyalite reservoir between 7200-7800’ on a NE pitch I got lots of whumphs and shooting cracks while braking trail. This was a shallower snowpack than most other areas, it was still easy to break into basil facets with skis on.

Region
Northern Gallatin
Location (from list)
Hyalite - main fork
Observer Name
Spencer Jonas