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Observation: Snowbird periphery

Observation Date
1/8/2017
Observer Name
B
Region
Salt Lake » Little Cottonwood Canyon » Snowbird periphery
Location Name or Route
Snowbird Periphery
Weather
Sky
Overcast
Precipitation
Moderate Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Skies were a mix of Overcast to Obscured at times during the day. Temperatures hovered near 30 degrees at 9000 feet. Winds were ramping up to the Moderate Range on the exposed Ridgelines and at times channeling into more protected terrain features as well. Transport and or Wind Blown was Moderate with Active Loading on N and NE facing slopes near the Ridges. Snowfall was sustained from 1100 on until leaving the area at 1500 at an S2 rate.
Snow Characteristics
New Snow Depth
8"
New Snow Density
Medium
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Snow Characteristics Comments

Above 9000 feet the New Snow remained cold and dry throughout the day and the riding was excellent as reported by multiple parties.

Rain has been coming down since 1300 hours at 8000 feet in BCC; and at 2300 hours the temperature is 40 degrees.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
Yes, all of these: Natural Avalanche Cycle began around 1130 and continued for several hours with increasing sizes. All Avalanches were Soft Slabs ranging from 6 to 8 inches deep and 25 to 100 feet wide. Slope Cuts were easily triggering these Slabs on slopes with Angles > 35 degrees. Heavy Snowfall began around 1200 with rates of S2 sustained throughout the afternoon. SW Winds were actively loading leeward terrain features. Cracking was widespread and observed on slopes of 28 degrees and greater. Weak layers appeared to be Light Density Snow that was capped by the Denser Snow that had fallen since 1400 on Saturday. NSF's from Friday may have also been part of this Poor Snowpack/Upside Down Equation. Isolated Collapsing was also observed in valley bottoms near creek bed, and this may have been associated with buried SH, yet this weak layer was not confirmed.
Avalanche Problem #1
Problem
New Snow
Trend
Increasing Danger
Problem #1 Comments

See above and specific Avalanche Report. Continual abundant moisture combined with sustained SW Winds will Likely keep this Problem Active, Alive and Increasing through the next 48 hours.

Roof Avalanches with Slabs created from all the new snow since Christmas active from 2200 and on.

Avalanche Problem #2
Problem
Wet Snow
Problem #2 Comments

Widespread Wet Loose Avalanche Cycle from at least 8000 down to the Valley Floor due to rain on cold snow. And, as reported today in the Advisory, continual rain may possibly help initiate Wet Slab activity from 7500 feet down where the December Rain Crust is associated with Facets above this Rain Crust.

Wind Slabs are also a concern as inferred by the reports of Active Loading and Moderate SW Winds.

Danger appeared to escalate to High at noon today with the Widespread Soft Slab and Wet Loose Activity. And, with the forecast for unseasonably warm temperatures, abundant moisture, and Moderate SW Winds it appears that Monday will also have a High Danger.

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