@TrixieRuby , the regional / local avalanche forecast center forecasted avalanche conditions as "considerable" today. Without going into the weeds, an avalanche forecast is based on what is known about the snowpack (based on observations, digging snow pits, etc) and past and current weather, and the forecast is also based on aspect and elevation. Backcountry travelers use this information to determine what risk they are willing to take. As in life, some people are more risk taking/averse than others.
Resorts tend to know what areas and slopes are prone to sliding, and use a variety of methods to
mitigate avalanches - handheld ammunitions, remote triggers, ski cut - at various locations. This is a regular practice on storm days.
I didn't read today's avalanche forecast, but I'll add an anecdote that on 1/1, I observed surface hoar thanks to a friend's kid noticing how "pretty" the snow was. Since then there has been an additional ~30" of snowfall and really high winds. The overall snowpack is not deep. I am not sure if it's what got buried and turned into an unstable layer, but if someone told me it was the surface hoar I saw, I wouldn't be surprised.
I actually pulled up today's forecast:
https://www.sierraavalanchecenter.org/forecasts/#/central-sierra-nevada (you might have to click to 1/10 if it's no longer "today")
It does seem like what I observed on 1/1 was the weak layer.
ETA: I am not in the ski industry or a forecaster. I'm merely more observant and into this stuff than the average duck.