Regional Conditions for Northern Madison

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: D. McCabe

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: D. McCabe

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: D. McCabe

From (5/17/20): "...WS - ASu - R3 - D2 - I SE face of Middle Basin Peak starting at 10,000' Estimated SZ of 30° Slab depth of about 8". We were out too late in the day and chose to ignore a number of observational warnings. We were lucky and remotely triggered the avalanche below us."

From (5/17/20): "...WS - ASu - R3 - D2 - I SE face of Middle Basin Peak starting at 10,000' Estimated SZ of 30° Slab depth of about 8". We were out too late in the day and chose to ignore a number of observational warnings. We were lucky and remotely triggered the avalanche below us."

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. As seen from the top of Andesite today (5/20) Photo: H. Dougherty

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. As seen from the top of Andesite today (5/20) Photo: H. Dougherty

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: M. Feller

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: M. Feller

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: M. Feller

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: M. Feller

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. Photo: M. Feller

A very large natural wet slab ran on the afternoon of 5/19 at the Yellowstone Club. (Screenshot from the Y.C. Timberline chair webcam)

Noticed a very large avalanche off the East aspect of the club. Happened between 2 and 4pm and propagated across half the ridge. Photo: Tommy S

From obs: "Here are a few snaps from yesterday (5/2/20), looking into the Absaroka from up on Emigrant. Fair bit of smaller, pockety wet slab activity in steep, rocky terrain near the middle/upper transition. I didn't see anything larger than D2 or any activity in true upper elevation terrain." Photo: B. VandenBos

From obs: "Here are a few snaps from yesterday (5/2/20), looking into the Absaroka from up on Emigrant. Fair bit of smaller, pockety wet slab activity in steep, rocky terrain near the middle/upper transition. I didn't see anything larger than D2 or any activity in true upper elevation terrain." Photo: B. VandenBos

From obs (5/3/20): "N facing gulley, probably similar results from the Pine Creek avalanche posted on 4/29. Avalanche appears to be natural and possibly a couple days old. Ran about 400’ wide in the cone and damned up the creek with massive cement-like debris. There were more similar avalanches on N facing aspects the more I traveled. The skinning was isothermic and sloppy as each step fell through the snowpack to the ground"

From obs (5/2/20): "Wet slab avalanche possibly triggered by wet loose/ point release from above in the cliffs. Adjacent to “The Gem”. The crown looked to be about 2-2.5’ deep." Photo: N. Sheil

From e-mail (5/1/20): "...the mountains are coming unglued with the 4 nights of no freeze and heavy rain.  My party ventured up pine creek to take a look and found this big one that ran either yesterday or last night. 

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From obs (4/26/20): "....a wet slide from a n-ne couloir up mission creek near elephant head in the absarokas between 10-11:30 this morning. Snow did not freeze over last night and was heavily saturated early this morning before the sun rose." Photo: @laura_delray

From obs (4/22/2020): "Early this morning we ascended near peak 10467 between Beehive and Bear Basin and skied a line off the south-east ridge. We noticed an old wet slide (a day or so) at the exit of the couloir we skied, and many more slides, point releases and large pinwheels off of south-east aspects of peak 10467 and on the saddle between peak 10467 and 10390. These all appeared to be from yesterday or the day before yesterday. On the north-east aspects there was an approximately 6" wind crust on top of a relatively isothermic upper layer (did not dig deep enough to see if it was isothermic throughout) that started melting rapidly once the sun hit it."

Photo: L. Ippolito

All surfaces except the upper North faces were getting wet and sticky. We observed lots of wet loose avalanches actively happening on SE-E facing slopes. We found some cold buffy snow on north-facing slopes, not amazing skiing. There was one small crown on a steep East facing slope that looked to be from the most recent storm but everything else was loose wet. Small wind slabs from the last snow seemed to be glued down today. Photo: S. Jonas

From IG obs (4/19/20): "Saw quite a few natural wet slides back in Middle Basin over the past two days, April 17-18. Witnessed several break loose naturally after about 2pm on anything from SW to SE slopes." Photo: @joshpelczar

From obs.: "This slide appeared to have happened a few days prior to when we observed it on the 16th. When we skied the skiable terrain at Dudley Creek the snowpack was stable, though snow coverage was thin." Photo: A. Pessl

Fresh drifts broke naturally along the ridgeline which became long running wet slides. 4/17/20. Photo: GNFAC

Fresh drifts broke naturally along the ridgeline which became long running wet slides. 4/17/20. Photo: GNFAC

Pinwheels of snow indicate the surface is wet and losing strength. These were observed at Bridger on 4/17/20, caused by a skier crossing above. Photo: A. Crawford

From obs.(4/17/20): "Today while skiing at the Playground in the Bridgers my party triggered a wet slab on an ESE 33 degree slope at 7,700' (HS-ASu-R1-D1-I). No one was caught or injured. We decided to turn around as the sun was roasting the snow at 11:45 a.m., and picked a low angle slope to ski back to the trail. Skier 2 descended and popped out a slab about 10" thick and 50' wide, but the slide was slow moving at first and he was able to ski away. The slide gained momentum pretty quickly and ran powerfully about 250' down the slope." Photo: M. Talty

From obs (4/12/20): "Noticed this slide yesterday evening on the way out of Beehive Basin, on the southeast facing aspect. It appeared to have come all the way down from the upper portion of the ridge on steeper slopes. We figured it slid sometime Thursday or Friday in the high temps. There were several other debris paths, but this was the biggest by far." Photo: @davidgerstenberger

From obs (4/12/20): "Noticed this slide yesterday evening on the way out of Beehive Basin, on the southeast facing aspect. It appeared to have come all the way down from the upper portion of the ridge on steeper slopes. We figured it slid sometime Thursday or Friday in the high temps. There were several other debris paths, but this was the biggest by far." Photo: @davidgerstenberger

Fresh wind slabs were triggered around a foot thick in Beehive Basin on Sunday 4/12/20. Photo: @jakobechacon

Fresh wind slabs were triggered around a foot thick in Beehive Basin on Sunday 4/12/20. Photo: @jakobechacon

From IG message (4/10/20): "Huge cornice release on north face of Blackmore today around 11am. North face was not hot yet but I am guessing the rocks on the back side transferred the heat?" Photo: @graeme.emerson

From IG message (4/10/20): "My party and I observed a wet slide off of the s-se facing aspect of the Sphinx today around 1pm." Photo: @laura_delray

Observed 4/9/20 at 3pm. Photo: T. Gittins

Photo: L. Ippolito

From obs (4/8/20): "My partner and I noticed this slide as we summited 10602 at approximately 10:30am, which is when I took the first photo and was able to capture the full runout. After our descent of the peak, we skinned back up to the slide to get a better look (the second photo). The slide appeared approximately a day old, with a crown 1-2 feet deep, on an almost directly north-facing aspect at 10200" elevation. It broke right along the rocks that had heated up in the sun, and was around 200-300 feet at its widest. We did not get close enough to determine which layer failed (suspected wind from the heavy wind-crust in the neighboring area), but the debris at the bottom indicated it was a wet slide." Photo: L. Ippolito

Cornice triggered avalanches in Mundy's Bowl at Bridger Bowl. Unsure if natural or skier triggered from the ridgeline. Observed the morning of 4/5/20. Appear to be dry slab/loose. Photo: T. Gittins

Close up of a crystal from the surface hoar layer buried 2-3 feet deep north of Bridger Bowl and throughout most of the advisory area.

From 4/3/20: "I dug a quick pit at ~7450’ on a protected east 36 degree slope - HS 240cm...ECTP18@175 on 3-6mm preserved surface hoar (photos -1mm grid)... All results repeated identically in a second ECT... Seeing the reactive SH layer I opted out of skiing anything that had a distinct rollover or was steeper..." Photo: Z. Miller