UDOT PLANNED AVALANCHE CLOSURES!!

Observation: Alta Ski Area

Observation Date
11/9/2018
Observer Name
Greg Gagne
Region
Salt Lake » Little Cottonwood Canyon » Alta Ski Area
Location Name or Route
Alta Ski Area
Weather
Sky
Clear
Weather Comments
Light NW winds (with occasional moderate gusts) along ridge tops.
Snow Characteristics
Snow Surface Conditions
Faceted Loose
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments
HS 20-45 cms (8-18")
Red Flags
Red Flags
Poor Snowpack Structure
Tour up Collins Gulch to below Mt Baldy before heading over to top of Sugarloaf lift. Was curious about two things:
  1. Haven't been to Alta this year, and wanted to get a baseline of the different crusts in the snowpack, and to determine if they were beginning to break down due to faceting.
  2. Was intrigued by two observations from Mark White and Chris Pond where they got collapsing and cracking. Visited proximity to where Chris got collapsing.
Photos below show snowpack structure on north aspect on Mt Baldy at 10,100'
Various crusts present, but they are beginning to break down due to the thin snowpack and strong temperature gradient which is faceting the overall snowpack. Breaking down the crusts is a good thing as otherwise we have a structure in place where the crusts can support more of a load, provide a bed surface, as well as shield basal facets and depth hoar at the ground. Crusts can also connect slopes, allowing avalanches to propagate more widely. If the crusts break down, once we do get an additional load of snow (which we will!) the hope is that avalanching will clean out the snowpack, rather than sliding on the crusts and preserving weaknesses.
Also got to the approximate area where Chris Pond reported a collapse and crack. This area had some wind-loading and denser snow on top of the buried crusts. I was able to get a full propagation with an extended column test (ECTP12) failing on faceted snow down 20 cms (8") just above a melt-freeze (MF) crust. With no additional load, this is not a problem, but it does highlight the kind of issues we may have once we do get additional loading on top of a structured snowpack (by "structured" I mean crusts which provide different layering). Another good reason why we want these crusts to disintegrate.
Photo of Mount Timpanogos from top of Sugarloaf. Haze and poor lighting, but photo does show the decent snow amounts (and likely faceted) at upper elevations.
Really appreciative that Alta is currently allowing uphill traffic as they are undergoing operations preparing for opening later this month. We all have to do our part and get out of the way of snow cats and sleds when they are working on the ski hill.
Today's Observed Danger Rating
None
Tomorrows Estimated Danger Rating
None