February 6, 2016

Weekend Avalanche Outlook

Heightened avalanche conditions in Chugach State Park this weekend: evaluate snow and terrain carefully; identify features of concern.

Avalanche concerns:

wind-slab-12Winds slabs up to D2 in size are possible above 2500′ on terrain steeper than 35 degrees.  Steep, leeward (primarily west to north) terrain is expected to be the most problematic.  Clues to identify include snow surface texure (etched, or sastrugi), denser/firmer snow that has been wind-packed (especially if hollow sounding-feeling), and cracks radiating from your feet.  Pole probing and quick handpits will be an effective way to get a handle on the wind slab problem.  Recent moderate to strong winds have redistributed last weekend’s sublime powder into firmer, wind-affected snow that is slabby in some areas.


persistent-slabPersistent slabs up to D3 in size are possible (low probability, high consequence) above 3000′ on terrain steeper than 35 degrees.  Big, steep, leeward (primarily west to north) slopes in the upper elevations are expected to be the most problematic.  Numerous persistent weak layers, still exhibiting propagation propensity in snowpit tests, have been identified in the snowpack across Chugach State Park recently including facets, depth hoar, and surface hoar.  Digging a full-on snowpit, examining the stratigraphy, and conducting an Extended Column Test (ECT) is a good means of better understanding the persistent slab problem this weekend.  Please share with us what you find!