Observation Date: 02/27/2014

Route/Location:
Skied off the summit of Mount Sentinel on North Ridge and NW gullies down to Clark Fork River at 6:05 PM after skiing a partial run on West slope above fire road.

Weather:
West Ridge skis better than on would expect with a 2″ light solar crust and some freezing rain/mixed ice pellets on top capped with 4″ of light new snow from noon on today. Mixed Precipt. has ended and made way for a wide variety of grainy snow types. Wet NW flow is still present, but is stalling out visibly over the missoula valley.

Wind:
Winds currently from the SW, but wind speed and direction changed to cold air from the East when I reached the Kim Williams Trail. Lots of dense wind slab on both West Ridge and North Ridge from last weekends storm. Currently 4″ of snow has been blown over the North Face and down into Hellgate Canyon from today, but as winds shift it is all moving back towards Missoula. So TONS of transport happening.

New Snow: 3-6″

Avalanche Activity:
West Ridge skis better than on would expect with a 2″ light solar crust and some freezing rain/mixed ice pellets on top capped with 4″ of light snow. Able to ski above and below crust variably with soft settled snow in the trees. Total depth is about 2 feet on bunch grasses, except by ridges where dense snow from 2/19 is bonded well below. Some sloughing on freezing rain/ice pellet layer.

North Aspect is much different. NW Ridge was heavilly loaded from last Sunday. The larger areas of wind slab were very dense and 3-4 feet thick for first 300 feet off summit. Felt some collapsing. Mid slope pack was about 3 feet deep and rests on rounded grains and 6″ of consolidated snows from earlier on rocks/talus. below 4,000 feet there was generally no base with 2 feet of fluffy snow. Felt lots of collapsing in last weekends snow. Top 4″ of new snow sloughs easily on freezing rain/ old snow interface in all areas steeper than 35 degrees. This type of slope is transitioning to upside down and will have a sensitive 1-3 foot wind slab resting on it by morning.

Other Comments:
I posted to remind people that lots of terrain opens up when we get this much snow in places we are not used to it. But after This wind event of the next 48 hours it will not be as tame as my ski Thursday evening. Many fatal avalanches have happened on sledding hills and river banks in the Rockies. After this event huge slabs will be found on the weak and unsupported snow underneath. I feel the freezing rain layers around the valley have preserved the old snow below, and lots of new snow overnight will be transported. Be extra cautious on low and mid elevation slopes even when you walk your dogs on jumbo, not to mention the depth of tree wells currently found in the alpine areas. Ski and ride safe everyone, and try your best to take someone along with you.

Observer: Andy Morruzi