Avalanche: Hatcher Pass

Location: Hatcher Pass Easter Avalanche Cycle

Route & General Observations

Took a flight over the aftermath of the Easter Avalanche Cycle at HP that occurred 4/4/21. The debris from 5 avalanches on Marmot covered the upper road and the Archangel trailhead with debris 300 yards wide and covering the snogo corridor trail. Debris from 1 avalanche crossed the upper and lower road with 2 of the 5 avalanches almost making it to the lower road. This was a historic avalanche cycle with many D3+ avalanches and many D2’s. DOT says this could be bigger than 1981 when the last avalanche cycle of this size occurred.
Thanks to Neacola Air for the flight today!

Photo credit: HPAC

Avalanche Details
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Trigger NaturalRemote Trigger Unknown
Avalanche Type Soft SlabAspect Unknown
ElevationunknownSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

Numerous naturals on mostly E, S, and W aspects with only a few on N.
Many D3's and several D2's.
Most avalanches were storm slabs and wind slabs. Some storm slabs stepped down or pulled out pockets of the persistent slab facet/depth hoar layer. Many avalanches released twice during the storm with most chunky debris occuring after 2:30pm when SWE increased to .1" per hour. This storm brought 11" of snow and 2" of water (SWE).

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

Every RED FLAG existed in the snowpack during this storm and avalanche cycle.

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

11" new snow and 2" water (SWE)
temps increased throughout the storm
winds gusting SSW to SSE to W 20-41 mph for 24 hours

Photos & Video
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