Category Archives: Avalanche Conditions

Monday, January 23, 2012

This advisory expires in 24 hours

BOTTOM LINE:

Natural avalanche are unlikely, human triggered possible. Small avalanches in specific areas or large avalanches in isolated areas.

DISCUSSION:

Hatcher Pass has been fowled by the evil wind. Riding conditions are on crust surfaces on almost all aspects, ranging from thin patchy firnspiegel zipper to thicker breakable wind crusts to solid, rock hard, foot thick wind slab. This is the bad news.

The good news is that the snowpack remains reasonably safe in terms of avalanches. There is a concern for triggering thick hard slabs loaded in starting zones and gullies. These slabs could be triggered if you find a variably weaker spot in the slab, or less likely, apply explosive forces. Hard slabs were naturally triggered during and shortly after the latest wind events last week. These hard slab avalanches were smaller in size and ran short distances (HS-N-R1D1-I). The probablility of triggering one of these slabs is small, but the consequences are dire.

Natural avalanches [multiple HS-N-R1D1-I] during and shortly after the wind event on the 20th were observed on the South East face of Marmot, West face gully of Marmot, lower East rolls of the Eldorado Bowl, first step of the North ridge on Skyscraper. All of these avalanches can be attributed to wind loading. Note that strong winds at Hatcher can effect many aspects.

Winds have stripped the upper portion of the snowpack away and we can now see the weaker basal layers that were previously buried ultra deep. Earlier in the season we had almost no chance of triggering these basal, weaker layers due to their depth, but this has changed dramatically. We now have a greater chance of triggering these layers in wind stripped and thinner zones.

Currently, the structure is poor, but energy is moderate to low and strength is high.

View Pits

–Jed Workman, Allie Barker