[MCR] Polar Circus cornice failures

[Public Mountain Conditions Report]

A huge cornice failure on Polar Circus on Thursday added a little  
excitement to our day, and we thought we should give a heads up.  
There was a report yesterday of another failure in the same place  
that was heard but unwitnessed.

On Thursday, temps got up to -3.0 in the shade, skies mostly cloudy.  
Overall, ice was plentiful and soft, mostly dry. At ~11:30, the sun  
had just briefly come on to the uppermost sections of the face and we  
had just traversed the big bench in the middle (just above where the  
pencil tops out) and were racking up at the base of the headwall when  
a summit cornice well to climber's right of the last pitch broke off.  
(Yesterday's collapse also occurred at about the same time.) The  
sonic boom when it released allowed us just enough time to look up  
and witness armageddon carom off the face and come straight towards  
us. We just made it under a rock alcove before most of the bench was  
strafed with large blocks of ice and rock, including the base of and  
first pitch of the headwall. Multiple 3-5m wide impact craters  
resulted along the bench.

That said, right now there are still numerous remaining cornices  
threatening the upper tier, although none of these are visible from  
the threatened area. These were likely formed during reverse loading  
conditions by the early winter arctic outflow systems, and are still  
extensive along the ridge above the climb. Currently, the sun does  
directly hit those to the left of the climb late in the morning, and  
the headwall pitches may be exposed to these. Something to watch out  
for.

Carl Johnston, RG
Nicholas Rapaich, AAG, ASG