Northern San Juan
AvalancheAnn Mellick · Dec 11, 2021 · Northern San Juan
Weather
Very cold start to the day with temperatures moderating through the day. Brisk NW winds.
Snowpack
The mountains just received a hefty new snow load in a very short time (storm totals since Monday on RMP: 34"/2.7" h20). This fell on bare ground on sunny slopes, where no signs of instability have been noted. New snow fell on weak basal snow on shady slopes and resulted in a widespread natural avalanche cycle. The snow gets firmer the higher one travels in elevation. Snow in the apline zone is quite wind affected with surface slabs .5"-4" thick. Steady transport-speed winds have and continue to move ample available snow above treeline. I felt several collapses today- one on an open westerly facing slope above treeline, the other on northwesterly terrain below treeline. Both of theses areas held snow prior to our last storm and are obviously harboring weak basal snow. Bottom line: the snowpack on shady slopes is weak and skier triggered slides are probable on slopes steeper than 30?. We need to give the snowpack time to adjust to the new load.
Avalanche
Avalanches are in this ob: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=67673