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Observation: Turnagain

Location: Sunburst

Date:
Observer:
Route & General Observations

Tour up the Sunburst standard up-track to look at the new snow and how well it is bonding with the old snow surface. We found bonding to be poor with buried surface hoar under the new snow.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Observer Comments

No signs of obvious instability. Pit results were very concerning - more below and in video.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Overcast and broken skies. Winds were moderate to strong from the East and blowing high and low on ridgelines as well as in the upper valleys. Snow devils prevalent off many ridgelines. Warm temperatures (mid 20'sF at 2,500' and 33F at sea level). Light snow was falling on the North side of the Pass, but the Souther side, including Sunburst had no precip during our tour.

Snow surface

Below 2,000': 4-5" of new moist snow over a 1-2" moist crust.

Above 2,000': Settling dense powder from the Valentine's Storm Cycle (Feb 13, 14 and 15). New snow from this cycle dropped 20" of heavy snow at Sunburst. Boot penetration was 8" deep while ski penetration was only 4" deep. Wind affected in many exposed areas, wind crusts and stubborn wind slabs up to a foot thick.

Snowpack

Above 2,000': Buried surface hoar (1cm) sits under the 20" of new storm snow. We had an ECTP 18 and 20 on a SW facing aspect at 2,850' on a 28 deg slope. We dug earlier at 2,400' in an area with known traffic prior to the storm, and we had ECTX here - we could clearly see that old tracks had disturbed the buried surface hoar.

Bottom Line: The new snow is not bonding well to the old snow. Don't be fooled by lack of red flags, or stable pit results, if you are in areas that see high traffic.

A crust 4-5" below the surface from the rain on Feb 14 is freezing below 2,000' and mostly supportable. There is buried surface hoar under the new snow in these lower locations as well, we did not dig in the lower elevations.

Photos & Video
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