Snow Observations List

At 5pm on 4/20/23 I dug a quick snowpit to look at the storm snow o the Bridger Ridge. at 8,400’ there was 36” of settled snow equal to 3.6” SWE from the last two days. Total depth was 311cm (~10’ 3”).

No cracking or easy triggered loose snow on small test slopes. Surface was getting more slab-like or cohesive. In general the snow was more stable than yesterday, but there was a ton of snow so still potential for big avalanches. Probably less frequent than the recent dry loose snow activity, but potential for larger slab avalanches or wet avalanches.

Stability of the new snow could become worse if wind increases and drifts the snow into dense slabs, or when warm temperatures and sunshine arrive later in the weekend and make the snow wet and weak. 

20-36" of low to medium density snow in beehive, bear, and middle basins.  Moderate west winds and overcast skies. It snowed lightly all day and the sun never came out.

We skied south, east, and west aspects. Snow was mostly right side up and was unconsolidated. Sluffs were running on steeper terrain, but other than that, we didn't experience any reactivity or signs of unstable snow.

By early afternoon on 4/19/23 the three feet of new snow was easily avalanching and running long distances with large volume. Video from Test Face/Lower Nose.

At 6pm, 4.19.23, the Bridger Range has received 37" of new snow in the last 20 hrs (29" were measured at the top of Bridger when the snow board was cleared at 1pm, and 8.5" have fallen since) equal to 2.2" of snow water equivalent (measured at Alpine weather station).

I skied up and down under the Bridger lift between 10am and 2pm. The new snow slid easily on steep slopes, mostly dry loose avalanches, but by the afternoon these were entraining large, dangerous volumes of snow. Video is from this morning, small test slope at 6,300', north facing. Now there is a lot more snow, and much more at higher elevations. It snowed heavily all day. Wind was moderate on the ridge, calm with moderate gusts below the ridge, and moderate/gusty on the lower half of the mountain. 

Large avalanches of new snow will be easy to trigger for the next few days, and large natural avalanches are possible. Conditions will continue to become more dangerous if heavy snow continues.

We observed a large slide at the Apron that was released from the Hidden Gully. In a whiteout, we couldn't tell the size, but it looked quite substantial. The slide didn't go all the way to the bottom.

New snow is not bonding well to the old snow surface.  Sluffing and running far on steeper terrain.  Photo taken on First Finger. Heavy snowfall and wind.

Had some loose wet slides on the fin today just after noon. Was about 3-6” deep at the new/old snow interface. Slide was slow moving but carried farther than we thought. 

Usual spring conditions. Out farming corn snow. Saw some activity from the warming sun.

Observed evidence of natural slide activity yesterday while snowmobiling Buck Ridge. First pics are on a northerly aspect off Sphinx near the wilderness boundary, second set of pics are south facing off Pioneer Mtn.

Approx coordinates of slide #1: 45.15872, -111.46923

Approx coordinates of slide #2: 45.22781, -111.46531

Was able to spot a deep slab avalanche from Gallatin peak, slab was at the headwaters of S Fork Hellroaring (N aspect @ 9800) Hard to tell when this released as it was a few miles away, I would estimate the crown being around 10 feet. Observed a small storm slab on a north aspect as well (1-2 foot crown). Also saw a few dozen wet slides that released earlier this week, some tearing all the way to the ground. 

This afternoon my group triggered a dry-loose avalanche on the north face of Big Timber Peak in the Crazies. The slide was about 12 inches deep, 50 feet wide, and ran about 1,000 vertical feet. Thankfully, no one was injured. We didn’t officially measure the slope angle but we’re estimating it to be in the 38-degree zone—prime avalanche territory. The slide consisted of new snow that fell during this recent storm. It hadn’t bonded to the thick crust underneath and released during the second skier’s run.

While skinning into Big Bear gulch, off Wisconsin creek, we encountered a couple of small whumphs in a flat meadow below treeline. We also encountered one instance of localized cracking within the trees, near the hollow created by a dead tree. At the top of the ridgeline there were small cornices, and we noticed significant wind loading higher up on Old Baldy mountain.

In our east facing pit, just below the Little Bear ridgeline, we found a large melt freeze crust complex near the surface, interspersed with layers of much softer snow and NSF. Below the stout crust layers, the snowpack drastically reduced in hardness, with fist hardness facets near 50cm from the ground. We had moderate CT results (CT 12 Q2 @140cm) within the crust complex, and more difficult CT results (CT 23 Q2 @30cm) within a layer of large (3mm) striated depth hoar near the ground. Our ECT test resulted in an ECTX, possibly indicating the strength of the crusts, which neither skis nor boots would penetrate through. Our ECT column did pull out of the wall as a cohesive block when we applied shear from behind. Our pit profile was submitted through Snowpilot.

Based on these observations, and the warming we believed would occur later in the day, we decided to not ski off of Old Baldy mountain, and rather took some laps at a nearby low-angle meadow. 

Pretty much the entire wall skiers right of the prayer flags back into beehive slid. Wet slide. Multiple crown lines and long running. 

Photo from IG 4/13/23: @waxeman

Small storm slab off the steep drift on skier's R/skinner's L side of upper Thunder Road. Also felt some cracking and collapsing when I (briefly) stepped off the skin track to get to the top of Pierre's Knob. 

skinned up to the ridge and observed 5-9 inches of new and accumulating snow forming into wind drifts that were highly reactive. Multiple remote triggers occurred while traveling N on the ridge, propagating  both on W and E faces of the ridge. Both Hidden and Northwest Passage slid with little effort down to an icy bed surface. Debris at bottom of hidden was substantial but great skiing. 

Pics below of a natural wet slide that came out of Close Call yesterday afternoon (4/11/23), debris ran to the bottom of moonshine.

From 4/11/23: Yesterday (4/10) Colters released a wet slide (approx 1-3pm) that filled the top of the wiggle and left debris 300ft past the south bowl traverse.

Today Stupor had a similar sized release just after noon.

The best noted natural release was a wet slab release on the southern edge of the football field that put a pile of debris below the cave.

Although I only photographed North Bowl slides that ran very far, most of the chutes showed signs of wet slides running from the ridge. These were both in the bowl next to PK and north bowl.

From Big Sky Ski Patrol: "Temps remained a little cooler than yesterday and generally topped out in the mid 40’s F. That didn’t stop the free water from moving
and continuing to destabilize the snowpack, primarily on solar aspects below 10,000’. Near full depth to full depth wet loose avalanches continued to naturally release in what was left of the A-Z’s as well as LRT which had not seen any activity yesterday."