Detailed Observation

ObserverGareth Brown

General Observations

Ski toured up North aspect of 33 mile today "RFS".  Found 40 cm's "16 inches" of settled snow from the most recent storm sitting on a rain crust up to 2500 feet.  Dug a pit at 3500' on a North aspect.  Found preserved 2-3mm buried surface hoar with 95cm's "3 feet" of new snow on top.  Got an ECTX on stability tests.  Definitely a false stable result probably due to the depth of the layer.  Also did not notice signs of instability like cracking or whumpfing on the approach.  

At 4000' our group reached a bench and watched a large natural avalanche come down from the basin between RFS and Cracked Ice.  We are unsure if the avalanche was triggered remotely by our group or was triggered naturally.  There was no collapse or audible whumpf in our area before the avalanche.  The slide started about 1000 feet away and sympathetically triggered another avalanche that extended for approximately a 1/4 mile or more.  The Crown line was significant in not only length and height, but also started from a very low slope angle which appeared to be in the 30-32 degree range, this should be visible in the pictures that I have attached.  Crown height appeared to be 2-3 feet plus.  Also observed a very significant natural avalanche off the North Buttress of Nicks where it rolls over at about 4000 feet.  Most of the slope avalanched and the crown was only broken where there is a minor gully running through the slope.  Crown height appeared to exceed a meter deep in some spots.  Both of these avalanches were on similar aspects and elevations.

This is a scary setup where stability tests and travel conditions that appear stable could lure you out onto a potentially dangerous slope. Also slope angles that would generally be safe routes most of the time may not be at this time. 

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Weather Observations

Observed Avalanche Activity