Wednesday January 6, 2021
Persistent Slab, Storm Slab
Travel & Terrain Advice
Avoid wind loaded zones for at least the next couple days until the wind slabs have had time to settle out on NE to NW aspects. There is even the potential for this extra loading to trigger some deeper weak layers in our snowpack.
Stay out of all avalanche terrain in an elevation band when the hazard rating is high for that zone.
Remember that Mt Washington is private land and there is NO touring uphill allowed inbounds, even terrain the hill has not opened (yeah the boomerang). At any point in time there can be snow cats, winch cats, explosive avalanche control and ski cutting going on. You endanger not only yourself but the workers doing their jobs by entering this terrain. The terrain around the hill (other than Strathcona Park of course) is also private land and touring there is considered trespassing. Please help the reputation of backcountry users and stay out of these zones.. Poor behavior makes it harder for us to gain access to areas we can go. There are plenty of other mountains on the island folks.. Just take a look in Phil Stone’s book “Turns and Tours”…
Tuesday: Limited reports for the storm, but that is probably because everyone played it safe and stayed home today and it would be hard to see the natural avalanche activity with limited visibility. One can expect there was a widespread cycle of naturally occuring avalanches during the storm. Hopefully the skies will clear and we can get a glimpse of the canage Wednesday…
Sunday and Monday: Mt Washington reported limited results with bombs and ski cutting on west aspects at treeline Monday. Neil B from Mt Cain sent in a report saying they had some loose dry avalanches in the area and that “death chute” had slid naturally.
There are a couple layers down in our island snow pack that have been producing interesting results in snow pit tests as of late. This heavy snowfall from Tuesday’s storm (especially where the winds have added a significant extra helping of wind transported snow) may be primed with enough weight to trigger these deeper layers. There is also the potential for the storm slab avalanches that will result from Tuesday’s storm to then step down to these layers making already big avalanches become massive.
Location: NE to NW aspects in large to very large features in the alpine and treeline elevation bands
Possibility of triggering: Possible to both natural and human activity.
Size: two to three and a half. SUPER BIG!!!
Well if it was not obvious enough….. Massive snowfall from Tuesday’s storm has caked the island hills. Extreme SE winds to be followed by strong SW winds will also transport this snow to cross loaded features and NW to NE aspects building wind slabs.
Location: All elevations and aspects, especially NW to NE.
Possibility of triggering: Very likely to likely to both natural and human avalanche activity.
Size: one to three. Yeah really big and plenty of them!
A large storm event dumped significant quantities of snow Tuesday Jan 5th with extreme winds from the SE transporting large quantities of that storm snow to lee aspects. Expect very wind affected conditions in the alpine, treeline and open zones below treeline.
|Surface||Vast quantities of new snow, wind affected snow and significantly wind loaded lees and cross loaded features.|
|Upper||Storm snow from Monday and early Sunday over a crust below 1500 m and over old storm snow above 1500 m|
|Mid||Old storm snow with a sheer layer at a snow density change (now down variable amounts due to wind transport)|
|Lower||Mainly settled snow with a rotted out crust from early season.|
Early Sunday snow flurries blanketed the mountains before the blue skies came out for the day. Monday saw a light to moderate snow storm. Temperatures remained cold over these two days and wonderful powder conditions existed. And Then!!!! Tuesday it went nuts.. A very aggressive storm system struck with heavy snowfall ( estimates at 40 to 100 cm ) and extreme hurricane force winds from the SE. This monster of a storm arrived in the early hours of Tuesday and went full force all day and well into Tuesday night.
Once Tuesday’s storm abates… Winds will switch from extreme SE to strong SW adding another aspect to our wind loaded zones. The snow will ease off Wednesday and Thursday. Thursday winds pick up blowing in the next system for Friday’s storm. Friday sees small to moderate amounts of new snow for the day.
Wednesday: A trace to 5 cm of new snow. Winds strong SW easing to moderate to light SW. Temps for 1500 m -2 to -4. Freezing levels 900 to 1000 m.
Thursday: Zero to 10 cm of snow. Winds moderate to extreme SE. Temps for 1500 m +1 to -4. Freezing levels 700 to 1700 m.
Friday: 10 to 25 cm of new snowfall. Winds extreme to strong SE going to moderate to light variable directions. Temps for 1500 m + 2 to -3. Freezing levels 500 to 1000 m.
Posted on Wednesday January 6, 2021 by Bill Phipps