As new snow begins falling Saturday and becomes heavy, fresh storm slabs will be building in open areas above treeline. When these slabs build to about 4″ or deeper they begin to pose a threat. These fresh slabs will be quite touchy and poorly bonded to the underlying snow surface (new/old snow interface). Be careful to avoid terrain traps where small amounts of snow can pile up deeply. Human triggered avalanches will be likely within the new snow.
(Click to enlarge graphic to read more…)
In areas above treeline, depth hoar exists at the ground. There are also 2-3 rain/melt-freeze crusts above just above this depth hoar and in the midpack. Any of these crusts can act as a bed surface and a weak interface within the old snow. This will be a problem on all aspects. Be especially cautious of steep, heavily wind-loaded areas above treeline, and unsupported slopes. Convexities, where there is a steep rollover, will be a likely place to trigger a deeper slab that runs to the ground with high consequences. This kind of danger is tricky and can be hard to manage, so a wide safety margin is recommended.
(Photo from Lutak Zone, 11/15, 2500ft, NE aspect)
6-12″ of new snow fell Nov 12-13, with a melt-freeze crust in the middle. After that, temperatures cooled down again and NW winds blew hard on the 18th.
We are expecting a storm coming in Saturday-Sunday, with 6-12″ of new snow likely. Winds should be light-moderate NW. More heavy snow is likely with a new storm on Monday-Tuesday. Temperatures will remain below freezing at sea level into next week.
( *star means meteorological estimate )
It’s time to start thinking avalanche. Dust off your gear and make sure it is fully functional. Put new batteries in your beacons! Do a beacon practice to start the season and keep your skills fresh. If you head into the hills, watch out for avalanche conditions, and be especially careful of rocks and hidden hazards like crevasses beneath the snow. WEAR A HELMET!
Education Video Links:
We have begun periodic conditions updates for winter 2020/2021. Click the + Full Forecast link below for each zone to read more.
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