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Observation: Brighton Perimeter

Observation Date
3/24/2019
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Snake Creek Canyon and Return via Pioneer/Dog Lake Chutes
Weather
Sky
Overcast
Precipitation
Moderate Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Only very brief periods of Broken throughout the day until exiting at 1500, the vast majority of the day Overcast. Temperatures appeared much more warm than their readings due to the intense late March radiation. Winds began the day SW and were moderate with moderate wind blown and or transport observed. Between the cross loading wind and the sustained snowfall throughout the day, tracks were filling in by the hour. Snowfall rates vacillated between S1 with brief periods when they ramped up to S4. By early afternoon the winds appeared to veer and be more out of the W.
Snow Characteristics
New Snow Depth
10"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Melt-Freeze Crust
Damp
Snow Characteristics Comments
Excellent powder riding up unitl 1130 on all aspects, and then the sun poked out for brief periods. With only periods of 5 to 10 minutes the E, SE and S got damp immediately. Initially the damage was limited as the clouds moved in and the snow returned, yet by 1300 all aspects except NNW, N and NNE got damp and subsequently crusted over. The top 10 cm were getting damp on the aforementioned three aspects. And, as per usual even the northerly aspects with slope angles < 25 degrees were damaged. Thin wind swept areas were observed in the alpine on the exposed ridgelines on SW, W and N.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
During periods of high PI widespread significant Loose Dry avalanches were very easy to trigger even on slopes with angles < 35 degrees, and these were running far while entraining large amounts of snow. These stuffs were digging down 15 to 25 cm, and appeared to be running on a graupel layer. Only two small storm snow slab avalanches were observed, one in the Pioneer Bowl area, rider's left of the Main Chute and the other down lower. Both of these slides appeared to have a contributing factor of wind loading. From early on, this same graupel layer appeared to be responsible for other density breaks and small storm slabs of insignificant consequence. Reports from Cardiff appear to validate these findings and Storm Slab with a contributing factor of Wind Loading appears to be the culprit. HN24: 18 cm to start the day with at least 10 cm more during the day until 1500 upon exit. HST: 43 cm
Avalanche Problem #1
Problem
New Snow
Trend
Decreasing Danger
Problem #1 Comments
Storm Slab with a contributing factor of Wind Loading as described above appeared to be the number one problem out there today, and this issue may continue to be lingering and suspect on upper elevation north through east aspects early on Monday. Yet, most likely they will settle out significantly in the next 24 hours. Any areas receiving velocities capable of transporting snow will remain suspect.
Loose Dry Avalanches were extremely easy to trigger even on slopes with angles lower than normal, and there appeared to be a natural cycle during the high PI periods noted in the steep NW, N and NE facing terrain in the Brighton Perimeter.
Avalanche Problem #2
Problem
Wet Snow
Trend
Increasing Danger
Problem #2 Comments
When exiting at 1500 there had not been enough radiation to precipatate a Wet Loose Cycle, yet it may have initiated later in the day. Regardless, the forecast for Monday indicates much more solar and this issue will be a factor with daytime heating and direct sunshine.
Cornices continue to be an issue of concern, and this latest event appears to have increased their already large sizes, and added to their loads. The rapid warming and intensely high temperatures forecast for the next 72 hours may contribute to potential natural releases.
Comments
Todays hazard in the areas traveled appeared to be a relatively high consequence Moderate, as there were no significant naturals and or slab avalanches observed. With the potential for a significant and large Wet Loose Cycle on Monday, Considerable may be appropriate during times of intense solar and daytime heating.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable