Observation: Hatcher Pass

Location: President’s Ridge

Date:
Observer:
Route & General Observations

Hatcher Pass is back in full winter following the Easter Storm with soft snow, below freezing temps and avalanche problems. Yesterday, we had two skier triggered avalanches. On 4/1, there was a slight break in visibility to make some professional observations. From Archangel lot we toured up President’s Ridge (East of Marmot) in a dense layer of fog to assess storm and wind slab thickness and sensitivity. The lack of visibility made seeing recent avalanche activity difficult. We did encounter whumphing & localized minor cracking in surface 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.
Obvious signs of instability
Recent Avalanches?No
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

-We witnessed audible whumphing in several locations at mid elevations below 3,500'.
-We crossed older mid-storm avalanche debris below cliffs and in gullies that released some time on 3/31. These were all D1 or less in size.
-1 meter cracking and slab failure underfoot in small localized areas, especially on terrain 35 degrees and steeper that had well-defined supportive crusts (see photo)

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

Widespread valley fog and temps around 23F degrees. Calm winds with some greenhouse affect when you got above 3200 feet.

Snow surface

Variable surfaces with wind scouring above 3000 feet. In some windward areas around 3,600', we could find 70cm deep snow or 10cm deep at the shallowest. In these shallower areas, it was easy to find breakable crusts over facets. There was soft F to 4F wind effected snow on northerly leeward aspects. In areas, this soft, wind deposited snow brought the height of snow up to 320cm. There were midslope wind waves that indicated upslope winds from the East. These actually helped with managing vertigo while skiing in the fog. Rimed snow particles were evident on shrubs & snow surfaces.

Snowpack

1 inch of new snow in the last 24 hours after the 23" Easter Storm (see Independence Mine SNOTEL). Graupel was found pooled in several locations with a size range of 3-6mm. The snowpack has an overall right-side-up characteristic with an older degrading crust below the storm snow. The new snow has evidence of wind affect and drifts were less than 2 feet thick. In more wind protected areas storm slabs were somewhat cohesive but trending stubborn. Near surface facets above and below the old crust is likely the catalyst for the whumphing and collapse of the the surface layer in some locations. While we did not have propagation in our pit, tap tests and a shovel shear with easy pressure showed failure potential within new snow and on either side of a MFC on facets.

Photos & Video
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