Additional comments by another backcountry observer who saw the slide. (we don't double post avalanches because it messes up the avalanche data base.) Brett will also probably go look at it today.

"I noticed this avalanche after reaching the top of Flagstaff this afternoon at about 4:30. The slide took place in the gully directly behind the top of "false Flagstaff," where the skin track from Alta Central tops out for runs into upper days or back down to Alta. The slope fractured just a couple feet below the ridge, and took out the entire gully, with debris running over a small cliff band all the way to the flats of Upper Days Fork, and leaving only a couple inches of late October facets as a bed surface. At 4:30 pm, the slide looked relatively fresh, as despite active drifting of today's light density snow, the 3-4' deep, ~50' wide crown looked quite sharp, and the extensive debris looked soft.

I called Alta Central to see if this slide had been reported, and quite unfortunately, it had not. If you are out skiing in the Salt Lake City or Park City area, and you trigger a significant avalanche or see another party do so--particularly in high use areas like ski area "sidecountry" or the slopes above the Town of Alta--it is absolutely imperative that you notify Alta Central at 801-742-3522 of the time, location, and characteristics of the avalanche, and indicate whether anyone is involved.

Comments:

Really impressive results with control work at the closed LCC ski areas today, particularly on upper elevation NE-NW facing slopes holding snow from late october's 16" storm. Very little activity to note on slopes that were snow-free on Thursday, 11/8 in upper Little Cottonwood canyon, aside from a couple shallow windslabs that released on S facing, ridgeline slopes above the town of Alta."

Cawley