Northern Gallatin

Went for a ski in the Mt Blackmore area this am. Temps were cold in drainages, but surprisingly warm in the sun. The objective for the day was to ski the mellow ramp spilling East off of the North ridge of Mt Blackmore. The East face of Blackmore had clearly seen significant wind. We stopped to dig a pit in the shelter of a terrain feature before ascending further. Our result of ECTP 3 at 135cm (total snow depth of 160cm) was a red flag, and turned us around quickly. The ECT failed underneath a 5cm thick knife hard Wind Slab on a fist hard layer of mixed grains containing 0.1mm FC and 1.0-2.0mm GP.

This morning while ascending a line on Sawtooth Mountain (Lower Novocain) we triggered an avalanche (ASu-SS-R2-D2-O)  that caught and carried my partner an estimated 180M and partially buried him. His leg and hand were unburied and excavation of the head was done in less than 2 minutes of the incident. The avalanche only involved new snow from the last 48hrs and was triggered on a MF crust/facet combo 30cm down(formed 1/30/22). The avalanche was 30cm at its deepest and 20-30M wide and ran 250M. We were lucky to find both skis and poles a little ways downslope.

Dug in Maid of the Mist Basin. Aspect 100 degrees. Elevation: around 9500. HS 165cm. ECTX. Quick shovel shear test produced no planar results. Very isolated and stubborn soft slabs high along ridge top in predictable locations.These were only a couple of inches thick.

We noted no signs of instability between Hylaite peak and Mt Bole (we conducted quick hand pits and shovel shears along the route). There was a large cornice collapse on an east facing ridge to the west of Divide Peak (photo) and, with sunny weather in the afternoon, we watched out for large overhanging cornices that were getting backed in the sun (photo). On the northeast face of Elephant Mountain, at ~9850ft, we recorded a  sudden planar Q1 shear with easy effort @15cm in a shovel shear test (photo). Although this site was in a small, isolated pocket of wind loading, we will be watching this layer closely going forward. 

We found an overall very variable snowpack in the alpine, with deeper wind affected snow on leeward features, usually sporting a thin to moderate wind board and very shallow, hard wind affected snow on windward features, usually rocky. Below and near tree line, snow was soft and cold on northerly aspects and a bit squishy and warm on more southerly slopes. In the couloir it’s self, we found a shallow snowpack averaging 30-70 cm in depth. Lower in the couloir we found a 6-8cm faceting crust over large facets. It was not reactive to non-SWAG hand pits and shear tests dug throughout the up route. Higher (approx 1/2 the way) in the couloir, the snow transitioned to rounded, hard to very hard (1F to P, some places P+ or K) wind affected snow uniform throughout the depth. This only changed on the more southerly parts, often near rock, where the snow was faceted and softer (4F to F), being unconsolidated and loose in a few places. 

Graph of Snow Water Equivalent (SWE) at SNOTEL sites in the GNFAC forecast area from October 1, 2021 to January 30, 2022. It highlights the extended dry conditions in January that contributed to weak layers forming at the top of the snowpack. GNFAC

We dug a snowpit about  50 ft below the summit of divide peak on a S facing slope.  Snow depth at the pit was 136cm. We had an ECTP 27 on some weak snow 58cm deep. It wasn't a very energetic fracture,  but it still went across the whole column.  

Skinned up into Maid of the Mist Basin and dropped over the ridgeline into the Basin below Mount Bole to ski a couloir to the north. We found widespread windslab on all aspects, nothing was reactive, but it was enough to make the skiing bad and unpredictable - one turn would be great, the next you'd be in breakable crust. 

We dug 2 snowpits, both on SE-facing slopes at about 9600ft. Dug down ~100cm in each pit looking for near-surface instabilities. Had no unstable test results, but found a lot of weak faceted snow in both pits. Lots of people out skiing didn't observe any avalanches or signs of instability.