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Observation: Alta Periphery

Observation Date
4/23/2022
Observer Name
Zimmerman-Wall
Region
Salt Lake » Little Cottonwood Canyon » Alta Periphery
Location Name or Route
Alta Periphery LCC
Weather
Sky
Obscured
Precipitation
Heavy Snowfall
Wind Direction
West
Wind Speed
Moderate
Weather Comments
08:00 start at Grizzly with light snowfall. 10:00 Upper Patsy socked in and gusting West moderate. 14:00 Catherine's pass light NW winds S5 snowfall at times. Temps remained cold all day. No sun.
Snow Characteristics
New Snow Depth
15"
New Snow Density
Medium
Snow Surface Conditions
Powder
Snow Characteristics Comments
Deep HST with drifts up to 60-80cm. Intermixed storm layering with some crystal type changes in upper 40cm. High quality, right side up powder.
Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Red Flags Comments
S3-S5 snowfall at times after noon, With heaviest from 14:00-15:00 in the highest reaches of Albion basin below point supreme. Winds were in the mid to upper teens and drifting snow along ridge.
Avalanche Problem #1
Problem
New Snow
Trend
Same
Problem #1 Comments
With over 60cm of new snow in 48 hours should be in the mix for storm slab. It appeared that the medium density snow had not really created a cohesive slab yet. I Did numerous boot pen measurements and it was straight through to the old melt freeze. The new/old interface was not a factor. CT14 SP x 2 down 35cm on some crystal type change. No propagation. Trail breaking was tiring but not onerous.
Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Same
Problem #2 Comments
Winds seemed well behaved and were creating small drifts and and overhanging new cornices on top of the old sagging behemoths. Travel on ridgelines was before intense snowfall rates and I never observed any gusts in the AM greater than 15mph.
Comments
Overall today was a solid return to winter. April provides. Despite numerous provocations of the newly formed very small and shallow cornices on test slopes along the Patsy ridge, the new snow would not really entrain. The first run was steeper Westerly facing terrain near the tower on Patsy back toward the Alta Summer Road. No sluffing noted at 10am. I purposefully stayed in the forest for visibility the rest of the day due to intense snowfall rates and did not observe the high alpine after 12pm. Kept slope angles at or below 30-32 the rest of the day. Performed one test profile at 10000' just down on the Alta side of Catherine's.
Photos:
1. The prominent crust laminates are visible down 40 and 70cm. With a notable, but not reactive layer of moist facets sandwiched between two melt freeze crusts down 70-80cm.
2. Some scary cornices out there atop Wolverine Cirque.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
None
Coordinates