Avalanche: Hatcher Pass

Location: Marmot; Death Gully/Lower Eldorado; test slopes

Route & General Observations

HPAC forecasters headed out to assess wind transport and loading from moderate to strong winds since the last Feb 10th snow. We toured up to observe Death Gully from Mid Ridge on Marmot and towards Eldorado beyond the test slopes and saw recent (12-24 hour) natural wind slab avalanches. We were able to trigger small D1 wind slab avalanches on test slopes.


Avalanche Details
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Trigger NaturalRemote Trigger No
Avalanche Type Soft SlabAspect West Southwest
Elevation 4000ftSlope Angle 37deg
Crown Depth 18inWidth 200ft
Vertical Run 600ft  
Avalanche Details

Observed a fresh (less than 12 hours given wind transport) natural wind slab avalanche (D2) off of Marmot in Death Gulley. Crown was 1-2' in depth wrapping around the south wall of the drainage. Had this been skier triggered, they would have been carried and possibly buried requiring rescue; debris depth was 4 to 5 feet deep.

We also inspected a natural avalanche on the lower Eldorado test slope. This avalanche ran full pathway, about 1000' across and 30' downslope. During our tour the test slope was actively reloading and we were able to intentionally trigger an additional D1 avalanche on the same path. See observation images for more details.

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?Yes
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

We saw multiple natural avalanches that likely occurred in the last 12-24 hours on SW-NE aspects above 3,500'. Red flag signs of instability in addition to recent avalanches included: pluming and blowing snow on ridgetops, shooting cracks up to 30' and some whumphing.

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

No new snow since the 10th/11th.
Snow was blowing throughout the day, gusting 20-35mph Independence Mine @ 3,550' and 30-60+ on Marmot @ 4,500'
We were blasted by the wind, observed plumes on ridges throughout the day, as well as rapid re-loading of terrain features capable of avalanching.

Snow surface

Surfaces were predictability moon-like with anti-tracks (raised uptracks), scalloped sastrugi, complete wind scour to ground and exposed, large facets up to 5mm which were too big to transport. We did get blasted by wind transport of smaller facets, the main grain type still available for transport. By our field exit time of 1400, we still saw blowing snow at ridgetop.


We dug a test pit on the lower Eldorado test slope which failed on isolation (ECTPV), 80cm down on rounding facets. See image.

Photos & Video
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