Mt. Tallac/Corkscrew

We toured on Mt. Tallac this morning with a east ridge ascent and a descent of the Corkscrew path. Departing the pavement at 10 am, there was a firm but superficial snow surface refreeze on open sun exposed slopes. Pole probing revealed that only the top 2 inches of the snowpack was melt-freeze with transitional snow, unaffected by previous melt below. Under the forest canopy, the snow surface refreeze was very weak, indicating that last night’s refreeze had been very reliant on radiational cooling. Melt-freeze snow surface conditions were prominent across the E-SE aspect terrain that we traveled. Shaded areas on NE aspects above about 8,500' held some pockets of snow where the surface had yet to undergo its first melt-freeze cycle.

Dropping off the ridgetop above Corkscrew a few minutes after 11 am, E aspect start zones at 9,100' were close to allowing for wet loose avalanches from intentional ski cuts. We triggered large rollerballs and 2 foot diameter pinwheels instead of a wet loose avalanche. At that time this start zone did not have sufficient free water production quite yet, but was close to getting there. As we continued to descend sun exposed E to ESE aspect terrain, we began to encounter sections of unsupportable wet snow at 7,800' and below. Shaded areas remained more supportable with less wet snow at the surface compared to sun exposed areas.