Observation Date
4/15/2016
Observer Name
Hardesty
Region
Salt Lake » Little Cottonwood Canyon » Alta Periphery
Location Name or Route
Alta/Twin Lakes Pass
Weather
Sky
Overcast
Precipitation
Light Snowfall
Weather Comments
Classic spring. Alternating graupel squalls with periods of sunshine. North wind noted by other observers in the Brighton perimeter, greenhousing noted in Cardiff Fork.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Medium
Snow Surface Conditions
Powder
Snow Characteristics Comments

Right-side-up conditions that became heavier down low as the day wore on.

Red Flags
Red Flags
Recent Avalanches
Poor Snowpack Structure
Red Flags Comments
Three wet slab avalanches with explosives in the upper Cottonwoods now. Two in upper LCC 9900-10,200' NE 3-5' deep running to the ground. One in mid-BCC 9800' West facing 3' deep running to the ground.
Avalanche Problem #1
Problem
Wind Drifted Snow
Problem #1 Comments

Forecast calls for gusty northerly to northeast winds overnight and tomorrow with plenty of snow to blow around. Should be responsive to active mitigation.

Avalanche Problem #2
Problem
Wet Snow
Trend
Same
Problem #2 Comments

Two wet slab concerns -

  • The storm snow blanketed the poorly consolidated mf grains; thus only a superficial mf crust up to an inch noted. Beneath that lies a few inches of wet grains that - with provocation - and perhaps gouging - may pull out as a wet slab now 10-16" deep. Collapsing indicates the mf crust failing on the wet grains below. Perhaps more pronounced on west to north to east facing slopes.
  • The three wet slabs initiated with explosives (LCC - 4lb air blasts...BCC - 2lb airblast) seem outliers EXCEPT for thinner areas where the wet loose isothermal snow has little to no strength. This would be the exception for human triggering - thinner weaker areas and more-so where another (perhaps loose wet) slide from above gouges into the weak substrate.

Beyond all that, any time of direct sun will quickly translate to easily triggered and natural wet sluffs in steep sunlit terrain this weekend.

Video
Today's Observed Danger Rating
None
Tomorrows Estimated Danger Rating
None