Things came unglued last night due to several factors including high precipitation rates, higher-density snow falling on lower density snow, and strong winds.🚧 #RoadClosureAlert: #LCCroad #SR210 is CLOSED to the public for @UDOTavy avalanche control work. This closure is in place until further notice.🚧 @UDOTTRAFFIC @CanyonAlerts @Snowbird @AltaSkiArea pic.twitter.com/ZgX64LF6ms— UDOT Cottonwood Canyons (@UDOTcottonwoods) February 6, 2020
Observations from Alta Base show that yesterday afternoon they reached about 18˚F and after some cooling in the late afternoon, temperatues climbed overnight and this morning, reaching 28˚F by noon today.
The radar loop below covers the period from 0900 UTC (0200 MST) to 2019 UTC (1119 MST) this morning. I've circled the high terrain around Little Cottonwood in red. The highest returns in that area are ground clutter, but ignoring that, one can see the very persistent radar echoes in that area, consistent with the ground-based snowfall reports.
Finally there is the wind. At Mount Baldy, sustained (red line) and gusts (green circles) have been climbing over the past two days and this morning gusts reached 80 mph. Hidden Peak at Snowbird reported a gust of 100 mph as well.