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Observation: Brighton Perimeter

Observation Date
2/18/2018
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Periphery
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Warm temperatures in the morning, and falling after noon. Winds were moderate out of the SW with gusts into the strong category. Tranport and or wind blown was light to moderate. The warming tempertures and previous winds appeared to have increased the density of the upper layers of snow, and limited the transport snow. Visibility was adequate to allow for observations at the upper elevation ridgelines and bowls for most of the day. Light snowfall began at 1400 and by 1630 rates of at least S2 were occurring.
Snow Characteristics
New Snow Depth
4"
New Snow Density
Low
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments

Extremely variable conditions in the mid and upper elevations due to the wind damage and melt freeze crusts. SE, S and SW aspects had m/f crusts of up to .5 cm. Wind slabs and or crusts were observed on multiple aspects and terrain features. Hard slabs of up to 6 inches thick, and soft slabs of up to 8 inches thick were observed even in the moderately protected mid elevations. Dense settled powder was available in the most protected treed areas. Of note, regardless of the warm overnight and early morning temperatures, cold dry snow was found on all aspects that weren't housing m/f crusts.

Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Poor snowpack structure continues to lead the list of important considerations with regard to potential red flags, and eventhough the Brighton and Alta perimeter has the strongest snowpack in the Central Core, areas of isolated thin snowpack and rocky areas remain suspect. Wind loading appeared to be the major player of concern today and it was likely that large sensitive slabs were created on mid slope rollovers and terrain features. The wind slabs observed in the terrain traveled at the low end of the upper elevation terrain were stubborn and unreactive. Heavy snowfall is in place with S2 plus rates at 2000 hours.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments

This problem did not appear to be an issue on Sunday, but with the additional loading from snow and wind as forecast for Sunday night and into Monday it is likely that this will generate another significant avalanche cycle Monday and into Tuesday.

Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #2 Comments

See above.

The danger on Sunday strictly in the area traveled appeared to be moderate, yet there may have been a considerable danger in the upper elevation wind loaded terrain.

The danger rating for Monday appears to be at least considerable and possibly high if the forecast for snow and wind verifies at the highest levels.

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