Northern San Juan
AvalancheAmy Pertuz · Apr 7, 2022 · Northern San Juan
Weather
Blue skies Thursday, with bone-dry air and ongoing winds from the North. Blowing snow had largely ceased, as the snow had blown around already and many fetches were stripped. It did not feel warm out there, and temperatures only flirted with above freezing at pass level.
Snowpack
All of the snow types, everywhere, and all at once. The wind really punished ski quality in many locations, though it did not appear to create new avalanches with this event. Raised tracks, next to wind pillows, next to refrozen roller balls, next to creamy drifted pow were the norm in many locations on RMP. Some protected features were able to escape the windpocalypse, and some slopes facing SW-W-NW held surprisingly soft snow where recent winds drifted it into subtle terrain features. This would be in close proximity to very stiff wind pillows, sastrugi, and stripped areas, though. Easterly slopes were smoother and looked more appealing, but the mix of crusts and dry snow without much warming kept the bandwidth narrow for tasty turns on this aspect. The variability required constant vigilance. The good news is it is increasingly hard to buy an avalanche after the recent weather. A pit on a NW aspect NTL showed a HS of 187cm, with the PWL from mid February 90 cm from the surface. The slab over this weak layer is mostly 1F, and this yielded no results in small or large column tests. The slab over this PWL is much thicker and stiffer on nearby NE NTL slopes, where HS is over 2m. I was able to initiate a propagating result, however, with 3 very hard extra taps on the ECT on NW NTL after ordinary tests were completed. This suggests that you could still trigger a persistent slab if you found a thinner spot to impact it from. Bonding and rounding of this (still porous, still large grained) weak layer is visible. The stiff slab protecting the PWL from skier impact seems to me more at play than the actual strength of this weak layer, as far as a lack of persistent slab avalanches in recent days. But it is trending a little.
Avalanche
No new avalanches observed. Some recent debris on Brown Mtn from a NW gully ATL, unknown vintage. No shooting cracks or collapsing. Some localized cracking in wind pillows.