Andesite Ridge/ Castle Valley

Quick report

Collapsing

isolated

Our AIARE2 group set out to try and investigate both the Windslab and Persistent slab problems listed in the forecast. We were curious about the sensitivity and distribution of these problems in the NTL and BTL regions of the Andesite Ridge/ Castle Valley zone. Winds were significantly less then forecasted through our tour and we were surprised by the lack of sensitivity of triggering of windslabs near ridge top. We saw several examples of the JAN 2 Buried Surface Hoar that still remained large (8mm) upright and sensitive to trigger on both undercut test slopes and in stability tests. Series of on the go observations (test slopes, hand shears) and a series of hasty pits with stability test revealed that the Jan 2 Buried Surface Hoar was still very pronounced (8mm) and sensitive to trigger. Hasty pit dug on a east aspect @7280' on a 23* slope where we conducted - CT 16 SC, PST 30/100 (END) With a 40cm Fist to 1 Finger slab overlaying the Jan 2 SH. Utilized test slopes to investigate sensitivity of newly formed wind slabs and small cornices. Both were faily stubborn to trigger along the lower portions of the ridge.

Weather

Air Temp

Below Freezing

Cloud Cover

obscured

Wind Loading

light

Recent Snowfall

Trace - 5 CM by end of day

Snow Avail For Transport

moderate amounts

Light SW winds gusting to moderate speeds over ridgetop, Obscured sky cover in the morning transition to overcast skies in the afternoon, Light (S1) snowfall throughout the day with several short periods of graupel.

Snowpack

HS 130 cm at 7280' In Castle Valley. F-1F Slab overlying JAN 2 SH (8mm) (83 cm). Crust facet combo just below that is also showing poor structure. Did not dig past Dec 19? Rain crust as it has shown to be substantial in this area and effective at bridging the early season FC.