Detailed Observation

Date2019-04-28
LocationEastern Alaska Range
ObserverLea H
AvalancheN

General Observations

Skinned up Gulkana West/W Phelan Creek from Arctic Man parking lot. Experienced frequent settling from ~4100ft onwards, all the way up the valley and onto the lower section of the glacier. Pit at ~4300ft on SW aspect, ~20°,showed starting from top: small amount of rounded grains (guessing recently wind deposited), melt crust, rounded grains, facets at approx. 15cm depth, melt crust, facets, rounded grains (thick layer), decomposing melt crust with thin facet layer above and below crust, … 

At this pit location, ECT block broke while cutting at facet layer above melt crust, i.e. ECTPV@15. We are confident that this layer was the source of the whoomphing. 

Quick hand pits while skinning confirmed that crust/rounded/facets/crust layering was present along the extent of our route. With increasing elevation, the amount of rounded grains/cold dry snow between the melt crusts increased. 

Dug second pit at approx. 6400ft, SSW, ~35° (small test slope at base of Institute S face). Top layer was hard melt crust (no ski penetration, able to kick through with somewhat forceful boot action). ECT again broke at facets above second melt layer on cut. Then attempted to cut so gently that block would survive cut and got ECTP@facets#7. ECTNR for rest of block after removal of top sliding layer. When forced with shovel, remaining block moved in smooth fracture across entire block at melt crust/facets interface approx. 1m down. The top layer which was very reactive in ECT did not react at all to boot packing but moved immediately when cut e.g. in switchback corners. Decided not to climb/ski Institute S face.

Saw 2 fresh looking naturals on W aspects, multiple older looking ones on E/NE aspects. Older releases looked like storm/wind slabs and crowns had been blown over. Fresh ones looked like they slid on the facets-on-melt-crust we observed. Looking over the saddle to Canwell we saw one fresh looking, snow machine triggered slide on NW aspect. Size of all somewhere in the D1-2/R1 range.

Snow quality was overall not great. Skied almost only aspects that get a lot of sun and it was mostly breakable crust, not the corn we were hoping for. Judging by the other reports from this weekend, N facing would have been the way to go. Couple of open, moulin-like holes on lower part of Gulkana West glacier.

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