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Observation: Patsy Marly

Observation Date
3/10/2022
Observer Name
Trenbeath, Groves
Region
Salt Lake » Little Cottonwood Canyon » Grizzly Gulch » Patsy Marly
Location Name or Route
Patsy Marly North Face
Weather
Sky
Few
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Beautiful March day in the Wasatch. Cold temps, in and out clouds mixed with sunny blue skies, and light NW winds.
Snow Characteristics
New Snow Depth
5"
New Snow Density
Low
Snow Surface Conditions
Powder
Damp
Snow Characteristics Comments
Deep powder snow after a multi-day storm event that produced upwards of 40" of snow. Heavy snowfall accompanied by wind yesterday created dense reactive storm slabs. The final 4"-5" that fell last night was low density and came in with little wind. With cold temps and occasional cloud cover, was hopeful that solar aspects would stay dry but by late in the day it was evident that the surface was damp enough for crusts tomorrow.
Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Heavy snowfall combined with wind created reactive avalanche conditions within the storm snow yesterday but those instabilities had largely settled out today. We observed lots of traffic on steep slopes facing the south side of the compass with no activity. Folks were avoiding steep, northerly facing terrain. On slopes that we traveled, we found no signs of instability within the most recent snow. Northerly facing slopes were heavily wind drifted, and with the current persistent weak layer problem, we generally avoided them but for a few small test slopes where we likewise didn't observe signs of instability within the new snow. I was surprised by the lack of natural avalanche activity in upper LCC. What I observed looked to be mostly sluffing and storm slab releases during high rates of PI, and these had mostly been filled back in. I think this correlates with the spatial variability of the PWL above treeline.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Decreasing Danger
Problem #1 Comments
The buried persistent weak layer of faceted snow that formed during the Jan-Feb high pressure is the primary concern. From my limited perspective visiting the range, it seems to be more widespread in sheltered terrain near treeline and below which is consistent with what I have found in the La Sals. At upper elevations it is variably located. This makes things tricky up there where there are less obvious signs of instability such as collapsing and whumphing. These red flag warnings appear to be more present at lower elevations. Regardless, a slab up to 3' thick now exists over this PWL, and and any avalanche failing on this layer would be extremely dangerous.
Avalanche Problem #2
Problem
Wind Drifted Snow
Problem #2 Comments
Most northerly facing slopes at upper elevations are heavily wind loaded. Deep drifts and sculpting were observed. These deep drifts have added additional stress to any slope that has the buried persistent weak layer.
Snow Profile
Aspect
North
Elevation
9,800'
Slope Angle
28°
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates