Route
Eddies to 2200′
Weather
Temps: Mid 20’sF
Wind: Moderate from Northeast, 5-10, g-20mph
Sky: Obscured
Precip: Snowing
Rain/Snow line: Just above sea level along Turnagain Arm
Obvious Signs Of Instability
Recent Avalanches- Yes, many Small (D-1) avalanches on steep wind loaded features
Shooting Cracks- Yes – Under skis in areas where the snow was more wind loaded
Collapsing – Yes – Several areas just above the convexity of a steep roll, collapsing caused several remote
avalanches several feet away on a steep convex rollover.
Glide Avalanches/Cracks- No new activity observed
Surface Obs –
450′: Parking elevation – 4″ new on large grained facets and buried surface hoar
1000′: 6″ new snow a few inches of facets on ground.
1500′: 6″ new snow on 4″ of old rotten (faceted) snow on ice crust bed surface
2000′: 8-12″ of new snow on pockets of 2-3″ old windslab. This slab is sitting on 4″ of faceted snow on
crust bed surface. (see photo)
*Eddies had more new snow than areas further South in Turnagain Pass. Sunburst only had an inch
of new snow at the parking area compared to Eddies which had 4″.
Snow Below the Surface:
Widespread facets were found under the 6-12″ new snow load. There was on average 4″ of old faceted snow
sitting a firm ice crust layer between 1400′ – 2300′. On top of the facets sits pockets of old wind slab (up
to 3″ thick.) This was not found everywhere, but 6-12″ of new windblown snow sits on top of this old windslab. The facets were well developed, ranging in size from 1-3mm. Facets sitting on the ice crust bed surface were large (3mm) with striations visible with the naked eye. See Pit photo below for pit details. Tests: ECTX, ECTN3 at 15cm below the surface (new wind loaded snow.) We also had consistent ski cut tests on wind loaded slopes steeper than 35*.
The current structure of the top 1-1.5 feet of snow is poor. The combination of new snow and wind
loading is adding stress to an already weak layer of old faceted snow that is sitting on a hard slick bed surface. This
is most reactive at elevation between 1500- 3000′ where a firm ice crust below exists. We did not go into
higher elevations where the ice crust disappears, but widespread facets have been well documented for the
last two weeks at all elevations. Small human triggered avalanches 6-12″ deep have been documented today on steep
wind loaded features. These wind slabs are soft and easy to trigger underfoot. If we continue to get more precipitation and wind these slabs could become larger and stiffer, thus creating more of a hazard with the potential to bury person. In Portage Vallley where more snow has fallen over the last two days combined with strong winds, natural avalanche activity has been observed in this elevation band. See photo below.
