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Observation: Argenta

Observation Date
3/20/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Mill D South » Kessler » Argenta
Location Name or Route
Mid BCC: Argenta/Mineral
Weather
Wind Direction
West
Wind Speed
Light
Weather Comments
Winds were light and steady out of the west and it appeared that the upper elevations were receiving greater velocities than the lower elevations. Yet, no transport was observed. Temperatures were in the lower teens very early in the morning and rose rapidly to the upper 20's by 0930, and then hit the upper 40's by mid afternoon at 8000. Skies were broken throughout the day and became overcast late in the afternoon. At 2200, scattered with temperatures barely below freezing at 8000. Morning update for 3/21, Wednesday: As of 0430 the temperature has risen drastically overnight and is 34 degrees with complete cloud cover.
Snow Characteristics
Snow Surface Conditions
Powder
Melt-Freeze Crust
Damp
Snow Characteristics Comments

Melt/freeze crusts were observed even in very sheltered flat and low angled terrain in the valley bottoms of BCC at 0900. Fortunately, once you achieved slope angles of at least 25 degrees on northerly facing terrain the surface conditions were still cold dry snow. Foot Penetration at 7000 feet was 8 inches, and at 8400 18 inches. Riding was excellent in light density snow that was at least 4 inches deep on NNE, N and NNW aspects up until 1200 when leaving. And, at 8400 feet these northerly aspects had bottomless riding with settled storm snow from the past weekend as a rebounding base below the light density surface conditions. Of note, the surface snow was sounding like it had already faceted when turning, and SH was visible. At 1200, northerly facing low angle terrain (< 25 degrees) still had a frozen m/f crust. Elsewhere on other aspects the surface was either damp, moist or saturated.

The superb settled powder riding as found today will continue to become more isolated and confined to strictly due north with slope angles > 30 degrees with the warm temperatures and the quality will decrease as the snow settles and becomes more dense.

Red Flags
Red Flags
Recent Avalanches
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
Rapid warming was obvious and wet loose was still an issue today in the afternoon on aspects on the lower half of the compass. Of note, the warm temperatures that were in the initial phase of the latest event appeared to have helped "sieze up" the new snow/old snow interface and below, and there was a thick knife hard prestorm surface. Below 7500 feet there was still evidence of moist snow below this hard prestorm crust.
Avalanche Problem #1
Problem
Wet Snow
Trend
Same
Problem #1 Comments

See above, and unfortunately overnight lows are forecast to continue to stay above the freezing mark at and below 9000. Wednesdays forecast for cloudy and in the mid 40's at 8700 feet may help continue the wet loose problem even on northerly facing terrain at and below this elevation threshold.

Loose dry avalanched in extremely steep northerly facing terrain still presents a manageable problem unless in high consequence terrain.

Danger strictly in the areas traveled today appeared to be low, and likely moderate in other areas with the above cited problems.

Avalanche Problem #2
Problem
Cornice
Trend
Increasing Danger
Problem #2 Comments

Cornice failure as reported from Timp may serve as an a precursor/indicator for more of the same with the extreme highs and possible greenhousing forecast for the next few days.

As indicated by the observation from Timp, Deep Slab and Persistent Slab continue to be a potential problem out there in areas outside the Upper Cottonwoods. As stated for the last few months: areas with thin cover and in rocky terrain have a lingering low probability/high consequence possibility for avalanching. And with the forecast stating that the overnight lows at 9000 feet and below for the next three nights, currently dormant buried weak layers in low, mid and upper elevation terrain may become suspect by Friday morning.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate