Southern San Juan
AvalancheChris Bilbrey · Mar 2, 2023 · Southern San Juan
Weather
Temperatures warmed nicely under bountiful sunshine. Generally light north wind, but brief periods of gusts into the 20s contributed to blowing snow along ridges.
Snowpack
We traveled on north through east to southwest-facing slopes up to about 11,200 feet. We found 12 to 14 inches of new snow below the treeline. New snow depths inched toward the 16 to 18 inch range at 11,000 feet and above. Unlike the two previous storms, this round of snowfall arrived with much colder air and is lower density. Warmer temperatures helping the storm snow settle kept the loose sluff threat confined to the top couple of inches of snow mostly reactive on steep, shady convexities. The snow surface on sunny slopes showed the effects of the strong March sun becoming moist and sticky by midday. This was more pronounced below 10,000 feet while the snow surface above that elevation on the same aspects was slower to soften. Steep, sunny slopes produced numerous rollerballs but none gained enough mass to entrain additional snow volume. The snow surface on northerly-facing slopes was less affected by todays warmth like their southern counterparts where we traveled. We observed moderate dirty shears below the storm snow on north to east-facing slopes likely influenced by the slabs soft nature. The snow in drifted areas along the ridge felt wind-thickened versus slabby.
Avalanche
Early morning light provided evidence of numerous loose snow avalanches or soft storm slabs on high southerly-facing slopes near Gibbs Peak and along the Knife Ridge between Babcock and Spiller Peaks. They likely ran on March 1, 2023 during a period of heavy precipitation intensity. These were mostly smaller in size, but a few on Gibbs Peak looked to have traveled a long distance down the slope growing large in size.