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Observation: Brighton Perimeter

Observation Date
1/9/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Perimeter/Twin Lakes Pass
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Rain/snow line hovered at 8500 feet throughout the day, and began lowering slightly around 1800. Temperatures were unseasonably warm, and at 8000 feet the high was in the low 40's. Rain and snow were steady throughout the entire day. Winds were in the moderate range at mid and upper elevations with the ridge lines registering velocities that prompted moderate wind blown and or transport. Minimal cornice development due to the high densities of the new snow.
Snow Characteristics
New Snow Depth
5"
New Snow Density
High
Snow Surface Conditions
Dense Loose
Wind Crust
Damp
Snow Characteristics Comments

The new snow was wet and or damp all the way up to 9500 feet, and even above that the high densities made the new snow thick and slow for riding. Trail breaking was thick in many places with the 30 cm fo fist hard old faceted snow being buried by the dense new snow.

Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Cracking
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
Heavy snowfall as described by the dense snow, not heavy PI. Wind loading was definitely occuring, yet the warmth of the new snow combined with the high water content appeared to limit the reactivity of the newly formed wind slabs. Despite this lack of sensitivity, the poor snowpack structure continues to be an issue, and there is now at least 5 inches of dense 4 finger to 1 finger new snow resting on at fist hard buried NSF's and new snow from Sundays event. The intense warming from today appeared to help limit the avalanche activity, but continued new snow and more water overnight and into Wednesday may help initiate another avalanche cycle.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments

The primary concern continues to be avalanches initiating on at least the 1/6 interface, and possibly down to the pre Christmas weak interface. At 2100 hours on Tuesday we are approaching the 1 inch SWE mark and we may be at a tipping point by Wednesday morning if the forecast verifies. Bridging from the warm storm today may serve as a poor indicator of stability, and this may allow for the possibility to get out further on to a slope than expected before avalanche release, failure and propagation. Natural activity may be occurring overnight, and with additional weight and loading on Wednesday this possibility appears likely and slides may be large.

Wet loose and Wet Slab activity was very possible today at 8000 feet and below.

Avalanche Problem #2
Problem
Wind Drifted Snow
Problem #2 Comments

As noted in the slide reported from the Meadow Chutes, as well as indicated by moderate to strong wind speeds noted by upper elevation remote anemometers, wind slab development appears likely. Again, naturals may be possible overnight and into Wednesday.

If the forecast is exceeded on Wednesday and storm snow totals ramp up past 20 inches the danger rating may hit High on Wednesday during periods of high PI. Regardless, Considerable appears very likely.

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