Gunnison
AvalancheCBAC Staff · Dec 19, 2023 · Gunnison
Weather
CLOUD COVER Broken TEMPERATURE (F) Mild NEW OR RECENT SNOWFALL (CM) 0 RAIN/SNOW LINE Not Observed SNOW AVAILABLE FOR TRANSPORT None WIND LOADING Light WEATHER SUMMARY Cloudy, light westerly winds.
Snowpack
Targeting the extent of strengthening in the upper snowpack from recent warmups on southerlies: On slopes less than 35 degrees, the snowpack structure was mostly dry and you could find persistent slab structure on previously windloaded SE or SW aspects. Above 35 degrees, the last few warmups have added several crust layers up to a few cm thick, offering some strength to the upper snowpack. Our impression was to get an avalanche on southerlies, you'd need to find a combination of heavily drifted onto a colder terrain feature, which we expect is isolated throughout most of the Ruby Range. A pit on a suspect-looking east facing feature at 12,000', showed a 2.5' hard slab (1F to P) over slightly rounding facets (4F-, 1.5-2.0 mm). An ECT produced propagating results after additional loading steps (32 hits). In steep terrain, snow surfaces are mix of melt freeze crusts or crust/facet/crust combos on southerlies, and windboard or softer, faceting sastrugi on northerlies.
Avalanche
And older, fairly destructive slide off of the SE side of Owen broke through Green Lake and blew chunks of ice 1' thick or more onto the far shore. I suspect this ran during the 12/3 cycle; any later than that and it would have likely been observed by Irwin Guides.