23-24
Still Dry in Portal
Rode up to the head of Portal Creek to area beneath Eaglehead Mtn and then around to the ridge overlooking Hidden Lakes. The trail is very low snow near the Portal Creek trailhead and the snow was wet to the ground beneath a stout crust. As we got higher up the coverage increased and even sunny slopes only had a couple inch thick surface crust over dry snow. On shady slopes there was still dry snow at the surface. We dug on a N aspect at 9400 ft just north of Eaglehead Mtn. The snowpack was 180 cm deep. We got an ECTX, but the facets near the ground were still soft and sheared off cleanly when pulling on the column.
We had no signs of instability today. The only avalanche we saw was a large slide on Eaglehead that had been previously reported over two weeks ago.
GNFAC Avalanche Forecast for Wed Mar 20, 2024
<p><span><span><span><span><em><u><span><span>Avalanche Accident near Mt. Blackmore</span></span></u></em></span></span></span></span></p>
<p><span><span><span><span><em><span>Two skiers were ascending a northeast-facing</span></em></span></span></span></span><a href="https://www.mtavalanche.com/taxonomy/term/259"><span><span><span><span>…; avalanche path</span></em></span></span></span></span></a><span><span><span><span><em><span> on the northernmost ridgeline of Mount Blackmore around 1 p.m. when they triggered a large, dry</span></em></span></span></span></span><a href="https://www.mtavalanche.com/taxonomy/term/304"><span><span><span><span>…; slab</span></em></span></span></span></span></a><span><span><span><span><em><span> avalanche that failed 3 feet deep, 150 feet wide, and ran 500 feet vertical. Debris piled up 4-8 feet deep. The avalanche failed on weak,</span></em></span></span></span></span><a href="https://www.mtavalanche.com/taxonomy/term/277"><span><span><span><span>…; faceted snow</span></em></span></span></span></span></a><span><span><span><span><em><span> near the base of the snowpack. One skier was injured and rescued by Gallatin County Search and Rescue. </span></em></span></span></span></span><a href="https://www.mtavalanche.com/node/31526"><span><span><span><strong><em><… and photos are here</span></span></u></em></strong></span></span></span></a><span><span><span><span><em><span>. </span></em></span></span></span></span></p>
<p><span><span><span><span><span><span>As evidenced by this accident yesterday and avalanche activity over the season (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span… log</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>), weak snow at the bottom of the snowpack is still a problem. Although the frequency at which avalanches are occurring is decreasing, the consequences of getting caught are not. Yesterday Ian and I went to Saddle Peak in the Bridger Range and found a poor snow structure which was </span></span></span></span></span></span><span><span><span><span><span><u><span><span>similar to the rest of our forecast area</span></span></u></span></span></span></span></span><span><span><span><span><span><span>: weak snow underlying the winter’s snowfall. The interface between the weak, sugary facets and slabby snow is noticed by digging with your shovel. The airy bottom layer can’t be missed. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Temperatures are going to warm and melt the snow surface, and at low elevations glop up the entire snowpack. Wet loose avalanches may travel long distances and could even trigger deep and big </span></span></span></span></span></span><span><span><span><span><em><span>dry</span></em></span></span></span></span><span><span><span><span><span><span> avalanches. Avalanches breaking deep are likely to be triggered 3 ways: from additional loading (snowfall or debris from wet, loose avalanches), from melt-water percolating down to the weak layer, or by triggering from a thinner spot, like the skiers near Mt. Blackmore did. My </span></span></span></span></span></span><a href="https://youtube.com/shorts/PyHc_9gjFWA"><span><span><span><strong><span… from Saddle Peak</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> shows this layer and discusses these points. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The danger will rise as the snow surface melts. Conditions will change rapidly, both temporally (in as little as 15 minutes) and spatially (soft skiing up high gives way to crashing through the wet snow lower on the slope). We have weak and unstable snow which is buried deep on many places. This depth makes it more difficult to trigger and more dangerous to be caught. Today, head home as the snow gets soft and punchy, and if you are on a shady aspect beware of hitting a thin spot that could trigger the entire slope. Dave’s recent </span></span></span></span></span></span><a href="https://youtu.be/Eb7HWFq7A0Q"><span><span><span><strong><span><u><span>… from Beehive Basin</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> is instructive for wet snow avalanches. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The danger will start out as MODERATE and rise to CONSIDERABLE as the snow surface wets.</span></span></span></span></span></span></p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Weather and Avalanche Log for Wed Mar 20, 2024
Freezing temps at night.
Propagation in low elevation bridgers
I was teaching a snow science program at crosscut today and our group got propagation (ECTP21) in our test pit on the facets at the ground, ~80cm down. The snow was 85cm deep at that location. We were on an eastern aspect around 6200' in a treed area. The students (bozeman 6th graders) were very psyched about getting to try what they'd seen on the mtavalanche youtube and seeing unstable results!
Slab north of Ross Peak
Photo from 03/19/2024. This avalanche likely happened yesterday or earlier.
Photo from 03/19/2024. This avalanche likely happened yesterday or earlier. Photo: J. Mancey
Forecast link: GNFAC Avalanche Forecast for Wed Mar 20, 2024GNFAC Avalanche Forecast for Thu Mar 21, 2024
Slab north of Ross Peak
Collapsing in the Boulder Drainage
From obs: "Toured up Mt. Rae in the boulder river drainage. Surprised to still find cold snow in spots and some still being blown around. Had some collapses and shooting cracks on the ascent. Shallow and suspicious snow for sure but a beautiful day out. "
Shallow skiing above the boulder
Toured up Mt. Rae in the boulder river drainage. Surprised to still find cold snow in spots and some still being blown around. Had some collapses and shooting cracks on the ascent. Shallow and suspicious snow for sure but a beautiful day out.