Quick report
- Cracking
- widespread
- Collapsing
- widespread
We experienced widespread collapsing and cracking on this tour. As expected, it was immediate in willows where new storm snow sits over large, weak, faceted grains. As we got more into the alpine, these cracks and collapses continued and gained distance (energy). A few were able to shake small shrubs more than 50' away and travel upslope several hundred feet (see below). Before the clouds moved in, we observed numerous D1 natural slab avalanches from the last 24-hour period on mid-slope features on both northerly and southerly aspects in the Valley of Sin. Our snowpit tests indicated that the recent load was still stressing our poor structure today (see "Snowpack" below).
Weather
- Air Temp
- 28
- Cloud Cover
- obscured
- Wind Loading
- previous
- Rain Elevation
- 2700
- Recent Snowfall
- 18
- Snow Avail For Transport
- moderate amounts
About 7"+ of new, wet heavy snow covered Fishhook Road above the Gold Mint turn. The slush flows were made worse in the last 24-48 hour period. Temperatures were in the near freezing level at mid elevations (2500-3500') throughout the day. We had broken skies and decent visibility for the first half of our tour. By 1330, clouds had moved back into the valley bottom level, and it was snowing 1cm/hour (S1) of wet, heavy snow. Winds were light out of the East.
Snowpack
There was a lot more snow on multiple aspects following yesterday's atmospheric river event. Before this, Southerly aspects had been scoured on 1/15. Height of snow between 2,500' and 3,500' varied from ~50cm to 150cm, depending on wind drifting. We were able to leave the surface rain crust behind at 2,700' and found supportive,
Collapsing was consistent and frequent as we changed pieces of micro terrain today. Hand pits and quick pits showed it was where mosly rightside up storm snow since 1/5 is failing on F hard, large depth hoar.
Our snowpit at 3,000' on a N aspect (where we got a large, propagating crack) was ECTV 75cm down on big, well-developed depth hoar.
Avalanche
- Size
- D1.5
- Type
- HS
- Aspect
- W
- Trigger
- N
- Elevation
- 3600 ft
We remotely triggered a small test slope in a drainage on the way up the Valley of Sin. On a more open slope, one of our settling whumphs propagated upslope, ~200' and we were able to see a perpendicular crack cross slope on the piece of terrain above us. Because we were managing our overhead hazard, this piece of terrain lacked the steepness to slide, but the energy in the snowpack was a clear bullseye that in steeper features we would have been able to trigger an avalanche (see snowpack structure).