March 19, 2016

Weekend Avalanche Outlook

ds-consSnowfall Saturday, potentially becoming heavy by afternoon, will increase the avalanche danger this weekend.

wind-slab-12While winds were light with the Wednesday-Thursday snowfall, and are again forecast to be light for the Saturday snowfall, touchy wind slabs up to D2 in size formed from the Wed-Thur snow in specific areas (upper elevation cross-loaded and lee terrain features) and this problem will be exacerbated by new snow Saturday.  The SW flow that is bringing more snow to the Anchorage area Chugach is loading areas that haven’t been loaded since the early season when the snowpack was thin.  Upper elevation (3000+’) terrain lee to the SW flow (which is quite varied due to terrain channeling) is expected to be especially touchy.  Look for relatively bulbous or fat, smooth looking pockets of wind loaded snow that is also relatively dense.  These wind slabs are likely to be human triggered if the terrain is not managed appropriately.

persistent-slabThe low probability, but high consequence, persistent slab problem still exists.  Persistent slabs are expected to be isolated, stubborn, and unlikely but if triggered may produce a large avalanche up to D3 in size.  Watch for them above 3500′, especially in heavily loaded areas where they may be stressed to near the point of failure.



loose-snowSmall D1 loose snow avalanches (or sluffs) are likely on terrain steeper than 35* above 3000′.  These sluffs are expected to be low volume and relatively fast on sheltered northerly terrain.  Sluffs on solar aspects, if the sun comes out or significant warming occurs will be slower moving but potentially much higher volume.



Cornicesicon-cornice have grown, and in some areas are now quite large.  The shape of their growth has also been altered with the change to southwesterly flow recently.  Give cornices a wide berth, as they can break off farther back than expected.  Be especially wary of softer, more freshly formed cornices; these will be touchy and likely have fresh wind slabs below.