March 4, 2015

Observations – South Fork Eagle River – North Bowl area

4:15-6:45pm

Obvious signs of instability:

Weather:

  • Mostly cloudy skies with some rain sprinkles and snow flurries
  • Temps in the mid 30s at trailhead elevation to upper 20s in the upper elevations
  • Light SE wind

Surface conditions:

  • Snow coverage has thinned since the last South Fork observation (February 27, 2015) due to melting from warm temps and wind scouring: exposed tundra and rock in many areas (especially in the mid elevations up to 3000′)
  • Supportable to heinously breakable wind slab
  • Rough sastrugi and exposed old, hard crusts
  • Some areas with up to a few inches of moist, dense powder (primarily upper elevation lee aspects)

Discussion:

New snow coming from Thursday (3/5) night expected to bond relatively well to the existing moist snow surface, except in patchy-isolated areas with exposed old, hard crust.  The lack of surface hoar and faceting, and the existing moist snow, at the surface should facilitate relatively quick bonding of the Thursday night snowfall.

As more snow comes Friday (3/6) night into Saturday (3/7), accompanied by stronger winds and a heavier precipitation rate, storm slab problems may develop and persistent slab problems increase.  This storm is expected to come in warm and cool down as it exits, making for a right-side-up deposit of new snow.  This is an ideal scenario, but stress from a potential 1’+ of new snow since Thursday and wind loading may elevate the persistent slab danger and a new, storm slab, problem may develop.

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