Sherwins

Snow mostly held off before 4 pm with less than an inch of new snow falling during my tour. Extreme winds and intense blowing snow limited the quality of field observations today. I was able to confirm that wind slabs are building over faceted snow in the upper snowpack. These slabs are hard, dense, and brittle, but less than a foot thick (5 - 25cm). In isolated areas, these slabs are sensitive to human-triggering.

Localized cracking. No shooting cracks longer than 3 ft.

BTL:  Skis sunk in about 6" (Ski pen 5 to 20cm). Boots sunk in up to the bottom of the calf (Boot pen 40cm). There were breakable (and skiable) melt-freeze crusts on all slopes except due north and steep/sheltered. S, SE, E, and W had ~ 3-5cm crusts. NE, NW and N (below 9000') had thin temperature crusts. Surface hoar was found on top of the crust in sheltered areas. It had become wet or re-frozen and was lying flat.  Most aspects became wind-scoured, the exception was terrain transitions at the edges of dense forests. By 3:30 pm the winds had reached high enough speeds to erode melt-freeze crusts on windward slopes and were beginning to access the snow below.

At the top convexity of a forest opening I dug down 1m and performed an extended column test to look at the sensitivity of the developing hard wind slab and the grains beneath. Results were ECTP1 and ECTP3 down 15cm in F hard 1mm near-surface facets. I triggered a D1 with a ski cut on the slope below.

NTL: Skis sunk in about 6" (Ski pen 5 to 20cm). Boots sunk in up to the bottom of the calf (Boot pen 40cm). Breakable crust on all except northerlies. NE, NW, and N sastrugi, wind board, or boottop re-faceted powder snow.  The same developing thin hard slab structure as described above was observed in isolated terrain features. I gave steep terrain a wider berth NTL with more uncertainty as to the depth and width of building slabs.