Field Report

Northern San Juan - CO

2024/11/08
Lat: 37.79, Lon: -107.607
Backcountry Area: Northern San Juan
Author: Jeremy Yanko
Organization: Forecaster, CAIC

Report Information

Observation Summary

Around 8-10" of new snow accumulated in this area over the last 3 days ontop of a snopwack depth that ranges from 45cm around 10,000ft, and upwards to 100cm at 12,400ft. There was plenty of evidence that wind had an effect on north/northeast aspects ahead of the recent loading event and probably during the storm as well. The snow surfaces were variable at this location and in this elevation range yielding thin wind crusts, firm 12" wind slab and Fist-4finger fluff. No obvious signs of instability were found and wind loaded features proved to be unreactive to skier pressure. One small natural slab avalanche was observed which presumably released during the height of the recent loading event on 11/6.

Area Description

Hazleton Mountain apron and ridge

Route Description

Arrastra Basin

Avalanche

Saw an avalanche

Natural release on a N/NE aspect NTL ~ 11,600ft in a steep complex gully system. Thinking it failed at the old interface in the early hours of 11/6, during peak precip.

i
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Date # Elev Asp Type Trig SizeR SizeD Problem Type Location
11/06/2024
TL NE SS N R2 D1.5 Wind Slab

Snowpack

Cracking: None
Collapsing: None

Generally a nice foundation has been stacked up in this area and largely supportive to ski travel between 10-12K. I did find some well developed facets at the bottom of the snowpack below 10,500 where HS sits around 40-50cm. Hasty profiles and probing also revealed two fragile crust layers which will likely continue to degrade but make for a tender setup and certainly concerning when we recieve our next significant loading event. Nearing 11k and above in elevation the snowpack showed good consolidation 4F hardness with a thin layer of moist small grain facets at the very bottom. Hopefully it will contiune to snow weekly for this month and beyond.

Weather

Mostly clear am to increasing high thin cloud cover by early afternoon. Mostly calm with an intermittent NE breeze, ~20F

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