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Observation: Snowbird periphery

Observation Date
1/17/2016
Observer Name
Zimmerman-Wall/ Snowbird AIARE 1
Region
Salt Lake » Little Cottonwood Canyon » Snowbird periphery
Location Name or Route
Lower Mineral Basin/Sinner's Pass
Weather
Sky
Few
Wind Direction
West
Wind Speed
Moderate
Weather Comments
The day started off cloudy but clearing skies dominated the afternoon. Strong west winds along 10k ridgelines were transporting snow throughout the day. By 1600, the winds had decreased to light NW. The temps below 9000 feet were near freezing. Still quite cold in the mid elevation shady terrain. Ridgelines were not pleasant to be on until very late in the day.
Snow Characteristics
New Snow Depth
10"
New Snow Density
Medium
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Damp
Snow Characteristics Comments
Depending on what aspect and elevation band you were on today, you could find a variety of different snow textures. The raging winds overnight into early morning certainly scoured some slopes to bare earth. Other slopes sported fat wind pillows and rippled surfaces. In the sheltered terrain the moderate density new snow since Saturday night was supportable and offered up quite good skiing. By the end of the day, some of the low angle solars had picked up some heat, but the wind kept excessive warming at bay in our location.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Certainly quite a few flags flying today. Literally. Our group was amazed at the variety of different snow conditions and avalanches throughout the terrain we visited and viewed. In our profiles on sheltered mid elevation Northerly slopes we found several reactive weak layers within the new storm snow since 1/14. However, we could not really find a defined layer of buried NSF below this storm slab. One profile to the ground in a 180cm deep area revealed damp facets that continue to show signs of rounding.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Same
Problem #1 Comments
The intense westerly winds did their work on the exposed slopes and certain wind corridors in upper LCC and AF were just hammered. Lee and cross loaded slopes had fat wind pillows that were reactive to skis and explosive tests. One pocket on a SW facing cross loaded slope pulled out over 2' deep on a steep mid-slope convexity and ran to the transition nearly 100 feet below. We purposely stayed out of the wind zone so as to avoid the issue all together. I imagine these wind slabs will become less sensitive within the next 24 hours, but may become buried and harder to spot with Monday's forecasted snow and increasing cloud cover.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments
Although our groups had trouble finding prevalent buried NSF or Surface Hoar in our terrain, I know it is still out there and may continue to be an issue. I am suspect of certain mid-elevation shady sheltered slopes where the distribution of this problem is known. We did experience Q1 Sudden collapses in our CT tests with Moderate to Hard taps. We also got one ECTP18 down 40cm. This appeared to be on decomposing stellars, perhaps from the light density snowfall on Friday that is buried beneath the denser storm snow of the last 48 hours.
Snow Profile
Aspect
North
Elevation
9,400'
Slope Angle
15°
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable