Southern Madison

We rode into the Taylor Fork, down into the bottom of Sunlight Basin, across Carrot Basin and to the Wilderness Boundary. We saw four persistent slab avalanches that likely broke last weekend or at the beginning of the week. All appeared to be snowmobiler-triggered R1-2, D1.5-2 avalanches at broke of the January layer of near-surface facets and surface hoar. Additionally, we saw one wind slab avalanche (R1, D1) in Sunlight Basin. This slide was fresh from this morning or yesterday. 

We dug a crown profile for the persistent slab avalanche in Sunlight (attached). ECTN24 on the SH layer buried 50 cm (20") deep.

We also dug above Carrot Basin on a northeast-facing slope: ECTP14 & ECTN15 on the NSF layer 50 cm deep. 

Near the Wilderness Boundary on a southeast-facing slope: ECTX

Persistent slab avalanches still seem possible, but it they have reached an equilibrium on most slopes that feels like the bottom end of MODERATE danger. Wind slab avalanches are certainly possible with the fresh slide as evidence as well are shooting crack in a drift as we rode in. Outside of large terrain, these will not be that large. 

New snow and increasing wind starting tonight will change the equation. The snowpack can take 0.5" of SWE without notching up the danger, but 0.75" with more coming would make human-triggered avalanches likely. 

From FB message: "Two snowmobiler triggered avalanches in Southern Madison. Riders did not have beacons or rescue equipment. Riders made it out safe luckily."

From FB message: "Two snowmobiler triggered avalanches in Gravelly Range. Riders did not have beacons or rescue equipment. Riders made it out safe luckily."

From FB message: "Two snowmobiler triggered avalanches in Southern Madison. Riders did not have beacons or rescue equipment. Riders made it out safe luckily."

Bacon Rind

Consistent crusts at  Around 75cm up and 63cm up 

Facets at 35cm up to Ground 

44.96280, -111.08678, 10:14

7850ft

68 E

20 degrees

HST 110cm

ECTP 25 65 cm up

ECTp 16 35 cm up

44.96019, -111.09583, 11:30

8578ft

59 NE

10 degrees

Hst110cm

ECTN25 75cm up

ECTP16 63cm up

We dug at couple and got propagation irregularly. Snow surfaces were soft on NE, Wind affected on S and E.  

44.94818, -111.06373
7505 ft
69 E
HST 95 CM
EctN 5 25 CM down
ECTP 19 65 CM down
CT2 q2 down CM 25
CT17 Q2 down CM 65

44.94458, -111.06444
7736 ft
55 NE

Hst 135 CM
ECTN 5 96 CM up
ECTN 17 82 CM up
ECTN 27 45 CM up

On the ascent, particularly above 8000 ft using quick pole insertion tests, my group noticed a first crust at about 12-15 cm, a middle soft weak layer, and then about 45-50 cm down a second crust, then weak soft snow to the ground. 

On a SE slope at 8750 ft elevation, my group performed an ECT and PST test. The snow temp was -15 C and the air temp was -14 C. 

Snow height was 115 CM.

Test results:

ECT X

PST 55 cm/100 on the weak layer of depth hoar from 25 cm to ground.  

The first 8 cm was fresh snow--dendrite or decomposing precipitation particles (F hardness). The next four layers from 107-67 cm were various layers, including a dust layer, mostly rounds, minimal faceting, 4F hardness. From 67 CM and lower, there was an increase in faceted snow, and of course, depth hoar for the last 25 cm.

Overall, a great day of low-angle tree skiing.