Saw a sizable avalanche on the north east face of Blackmore, likely broke mid storm and was partly filled in already - estimated 20" deep, 100' wide. Had shooting cracks and collapsing while ascending northeast ridge. Hand pits showed planar results on an 8" harder slab beneath all the blower on top.
We toured up the Ramp near Bridger Bowl Ski Area today. On our tour up we saw a few small cracks in front of our skis in the new snow. Also, there were a few crowns and sluffs on higher peaks in the range. The wind blew from the W/SW throughout the day, and it was transporting the new storm snow into harder snow drifts. We dug a pit at 8,300' on a NE facing slope. The snow was 5 feet deep (HS = 150). The weak, sugary snow below the 8-10" of new snow were not reactive in our tests (ECTX 2x). The storm snow is becoming more stable as we move further from this storm. Now, the main concern is terrain with wind-drifted snow.
<p><span><span><span><span><span><span>What a storm. Snowfall totals were 9” in the Bridger Range, 18” in Hyalite, 12” around Big Sky, and 14” in Taylor Fork. The snow measured .6-1” of </span></span></span></span></span></span><a href="http://snow.wyo.gov/snow-surveys/snow-water-equivalent-swe"><span><span… water equivalent</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, which means it was mostly 6-8% powder. Avalanches were widespread throughout the Bridger, Gallatin and Madison Ranges and involved only new snow. We have not heard of deeper layers in the snowpack breaking, which is welcome news.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The ski patrols were on the front lines fighting avalanches, a whumpf was felt in Lick Creek in Hyalite, and small natural slides were seen on History Rock, in Flanders and Sourdough Creek, and a skier triggered a small slide in Beehive Basin. Our </span></span></span></span></span></span><a href="http://www.mtavalanche.com/snow-observations-list"><span><span><span><s… page</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> has details and pictures of this activity. Ian and I skied into Mt. Ellis and dug a snowpit on the ridge. We found 12-14’” of new snow that easily propagated in our stability test (</span></span></span></span></span></span><a href="http://www.mtavalanche.com/images/23/mt-ellis-snowpit-profile"><span><s…;). With all the new snow we planned on staying out of avalanche terrain and this test result confirmed our assumption that triggering slides would be likely (</span></span></span></span></span></span><a href="https://youtu.be/4vtXECUhKbM"><span><span><span><strong><span><u><span>…;). It has been less than 24 hours since the storm ended and slopes need time to adjust. Wind is loading a few slopes near the ridgelines and I expect folks will trigger avalanches. Most will involve the new snow, but a deeper slide could break too. I sank to the ground in weak, faceted snow, a blaring sign that some slopes have a thin and weak structure (</span></span></span></span></span></span><a href="http://www.mtavalanche.com/images/23/boot-penetration-ground"><span><sp…;). Our to-do list is simple: measure slope angles and stay out of avalanche terrain. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>For today, the avalanche danger is rated CONSIDERABLE on all slopes. </span></span></span></span></span></span></p>
<p> </p>
<p><span><span><span><span><span><span>The mountains around West Yellowstone and Cooke City received 5” of new snow in the last 36 hours. The snowpack can handle this load and I do not expect natural avalanche activity. Wind is blowing north to northeast at 5-15 mph, and gusting to 30 mph in Lionhead. Wind slabs will grow with 5” of new snow. In the top 3 feet of the snowpack are a few weak layers that have not been a widespread problem, but they avalanched a week ago (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=VU_A-fTPYmw"><span><span><span><strong>… Park video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>) in isolated areas. With new snow, wind and a few areas of lingering weak snow, it’s a good idea to dig and make sure a slope is stable before getting into avalanche terrain, especially slopes above </span></span></span></span></span></span><a href="https://avalanche.org/avalanche-encyclopedia/#terrain-trap"><span><span… traps</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>With 9” of fresh snow, slabs of new and wind-drifted snow will be sensitive to human triggers. Wind is blowing and drifts will grow thicker even as snowfall tapers off (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=VU_A-fTPYmw"><span><span><span><strong>… Park video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Buried weak layers in the upper three feet of the snowpack could result in avalanches breaking deep and wide. Our to-do list is simple: measure slope angles and stay out of avalanche terrain. </span></span></span></span></span></span></p>
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
We observed a few small crowns on steeper road cuts in Sourdough today, NW and W aspects. 4-8" at crown, 20-40' wide, ~10' vertical. They looked like storm slabs that had run overnight, maybe on a density change in the storm snow. Debris piles were small and covered with 2-3" of new snow. Low consequence, but maybe enough to surprise a kid or a dog. Photos were taken shortly above the 2 mile marker.
We observed a few small crowns on steeper road cuts in Sourdough today, NW and W aspects. 4-8" at crown, 20-40' wide, ~10' vertical. They looked like storm slabs that had run overnight, maybe on a density change in the storm snow. Debris piles were small and covered with 2-3" of new snow. Low consequence, but maybe enough to surprise a kid or a dog. Photos were taken shortly above the 2 mile marker.
Was about 80% of the way up to the top of the middle meadow on history rock this morning when we remotely triggered a small avalanche from the skin track. Slide was just new snow that had fallen within prior 24hrs. Crown of about 8 inches, 20ish feet wide by 20 feet long. Face that slid was east facing. We took this as a sign to reconsider skiing something even as low key as history rock and decided to ski the skin track back.
[Dropped the pin for this observation exactly where I believe the observation to have occurred. Took an OnX waypoint while out there to help too.]
Was about 80% of the way up to the top of the middle meadow on history rock this morning when we remotely triggered a small avalanche from the skin track. Slide was just new snow that had fallen within prior 24hrs. Crown of about 8 inches, 20ish feet wide by 20 feet long. Face that slid was east facing. We took this as a sign to reconsider skiing something even as low key as history rock and decided to ski the skin track back.
[Dropped the pin for this observation exactly where I believe the observation to have occurred. Took an OnX waypoint while out there to help too.]
In Beehive with AAI Pro 1. Storm snow measured at over 30 cm, roughly double what was reported at Big Sky/YC. 5% density. Wind Slabs slowly building from L to M N winds, both WS and Loose Dry touchy on all slopes steeper than 35 with a MFcr as the interface - basically everything W, S, E aspects below 9500 (probably above too but we didn't go that high). One skier triggered wind slab observed low in the "tyler's" slide path on a SW aspect, 8700 ft, 35 deg, SS-ASu-R1/D1-I. No evidence of active persistent slab, 11x pits @ 8500 SE, HS 170, ECTX for all.
