Retallack

Easy hand shears down 10-15cm with Fist to 4F soft slab overlying small surface hoar & small surface faceted grains.

Could not add photos to my other post. See Lyle Creek post for avalanche details.

Skied Feb 10-13 in Lyle Creek drainage. Feb 10 MFCr/small SH down 120cm SE 2000m ECTX Deep tap 7 SP. One significant whumpf in a sheltered basin at TL SW 2100m. Skied steep W. Feb 11 strong solar in am. Crowns from numerous sz2 storm slabs convex features in ALP, suspect ran naturally during recent storm. Test pit E 2100m facets (suspect faceting crust/sh) down 120cm Deep tap 17 RP. One whumpf on a shallow/faceted spot climbing a ridge SE 2300m. Skied SE off summit of Brennan, avoided convex rolls, shallow spots. Feb 12 Skied steep W couloir, loose dry off rocks only sign of instability. Feb 13 skied steep fat supported SE slopes 2100-2400m deep unconsolidated storm snow. Skier Triggered a sz2 persistent slab from a shallow/rocky spot which propagated and pulled out two deep (~1m+) pockets from nearby convex rolls 2250m, micro aspect was South. Suspect sun crust/sh failure plane.

Toured London Ridge. Many natural avys seen (see pic), but only rare instability on our tour - no whomphs and only isolated cracking. No results from jumping on steep convex rolls. However, we still stayed in supported and lower angle slopes. Given the lack of instability on our tour, we guess the observed avys are old.

Lots of touchy slabs on anything steep, especially unsupported slopes and convexities. Remote triggered 2 separate size 0.5-1.0 storm slabs down 20-30cm from approx 20m away from the crown line. Snow very heavy but quite deep above about 1600m. Significant rain crust down around 20cm below 1600m. Skied elevations from 2000-1500m, east aspect. Heard but could not see what sounded like a sizeable (sz 2-3 based on approx 8-10 seconds rumbling) slide in what we have to assume was the next valley over.

Below treeline cutblock walking resulted in widespead shooting cracks up to 25-30m away. Pit dug at 1550m north aspect in cutblock showed surface hoar - 30mm. About 40cm of fairly consolidated slab overlies the SH layer. I would be wary of steep and unsupported BTL features.

Extended column test failed at 17 taps with a full propagation on a layer 55cm down. Failure was sudden. Failed on surface hoar crystals that were 10-20mm long.

We rode the cut blocks at bear face today. The snow conditions were wet & heavy. It was raining at the parking lot, but turned to wet flakes at about 1500 m. It was windy, and the flurries we intermittent. It did not seem like too much snow accumulated, however we just did one short lap today and weren’t out for too long.

Dug 3 pits and had planar, electric results with our compression tests on the storm slab 30-40cm down. While filling in our pits we triggered a small slab about 10m across that failed on the storm slab (see in pic). Large surface hoar layers also found here. A group ahead of us triggered a bigger slab in the middle cut block on a steeper slope that partially buried one skier, who was unharmed.

1st skier ski cut steeper shoulder with 30cm release ran less than 15m. 2nd rider skied lower angle line, no result 3rd skier second turn accidentally trigger a Sz 2, 70 cm deep, burried SH. Ran 250m. Propagated across ENTIRE slope (150m) Only half of it released. No involvement. Well supported feature at TL on north aspect 30-35 degrees. 1900m. 30-40 cms new snow in past 48hrs Previously skied in past 24 hrs multiple tracks in slide path.

Test Profile at 2000m on an East aspect right at the top of tree line. 30 degree slope. ECTN (moderate) down 12 cm's on DF's. ECTX on Jan 11 SH (5-7mm and rounding) down 40cm's CTM (15) down 12cm's on DF's, resistant planar DTN on Dec 8 IFCr down 110cm's Jan 11 surface hoar averaged 40 cm's deep and was evident on hand shears and in test profile between 1600 and 2000m elevation in this sheltered location. No reactivity in tests or on skiing up to 40 degrees. Snow surface mostly facetted leading to some sluffing on steeper terrain. Wide spread wind effect evident on snow surface in the alpine and at our test pit location. Below January 11 SH there was >60 cm's of 1F-P snow over the Dec 8 layer which is evident but breaking down.

Trip in Bear Face Cut Blocks: We could still feel crust below 1500m but the 10-15cms on top is starting to cushion it enough to be enjoyable skiing. Wind effect noted in open areas BTL as we ascended. Light west winds were transporting surface snow. Test Pit 1250m NE Aspect Surface hoar found down 75cms reactive in compression test (CTH23 RP down 75 SH sz 5 -laying flat) Results in 1 of 2 tests. Surface hoar down 30 (jan.11?) found in shovel shear test

-24hrs old Natural on steep unsupported lee feature from light overnight winds (<20km) Suspect failure layer Dec 8 crust (IFrc) down 100cm due to wind loaded feature. Didn’t step down to any lower Nov persistent weak layers but debris mass triggered slabs on Dec 8th on unsupported convex rolls in slide path. Viewed from across valley

Moderate sudden compression test results failing on the dec 13 surface hoar down 90cm.

Hiked up to ~300m elevation below the top of the Ridgeline. Tried to go above tree line but shooting cracks and small fractures (~20cms deep) formed on the lee side of the subridge we were on so we turned around. Skiing steeper open trees produced easily manageable amounts of sluff and riding conditions were fantastic!

Good mellow cutblock skiing on N facing terrain at the Bearface FSR, nothing steeper than about 35 degrees. Snow depth of 180 cm at 1750 m. Wind affected on open cutblocks above 1500m. Good medium-density powder in tree-sheltered cutblocks between 1400m and 1200m. Slough of top 10 cm of snow but otherwise no avy warning signs. Temps consistent around 0 C all day.

We enjoyed the calm between the storms. The terrain below tree line needs more snow to reach threshold for avalanches (and to open up for skiing). We observed a mid-storm instability down 10-15 cm in the recent snow and the Dec 11 SH down 35-40 cm that produced resistant planar results in snowpack tests. Snowpack depths at 1200-1500 m ranged from 80-100 cm.

Good day sled access close to retallack. It snowed for our time in the zone. S<1. Didn’t hear any whumf or settlement. Didnt see any avy activity other than slough skier triggered. Conditions of the snow were good to amazing! Probe 105-140 in all aspect we skied.

25 cms of 4F storm snow sits on a 1 cm 4F- crust, below this crust 50cms of 4F to 4F+ round grains overlie a 3cm ice crust with 4cm fist grains followed by a further 1 cm ice crust. The remaining 38 cm to ground are 4F+ round grains. 1)CTE 7 PC down 25. Nothing on the crust combo 2)CTE 4 PC down 25, CTM19 RP down 81. On the crust combo

Always exciting to see green pretty much across the board for ratings. Small pocket of wind slab ripped out @30 cm deep, on a rather exposed feature. A good reminder to keep your heads up out there.

Toured up Mt. Brennan. Lower elevations almost up until the lakes had a sun crust under 5cms of new snow that all became heavy late afternoon. Alpine was really good soft snow although warm except for the last bit to the summit.