Wayne Flann Avalanche Blog: January 5, 2021

YESTERDAY:

Crowds were not as bad! Snowing in the valley.

Another day of storm Skiing.

Mid Mountain skiing was deep and dry. Too good to be taking pictures!!!

Lower Mountain skiing was dry down to about 700 meters.

Monday Jan 4, 2021. 14:00 Hrs. -3 with a 25-40 KPH SW wind. 0 Deg C in the valley!!

Satellite image from the same timeframe.

Breaks pushed in after 15:00 hrs on Monday.

Weather Observations for January 5, 2021 taken at 06:00 Hours.

2240 meters -11, Winds were 55-75 KPH SE--Horstman Hut

2180 meters -9, Winds were 50-70 KPH ENE--Whistler Peak
1860 meters -8, Winds were 20-40 KPH SE --Rendezvous

1835 meters -7, Winds were 15-30 KPH S--Round House

1650 meters -7, 1 cm in 12 Hrs, 24 cm in 24 Hrs, Base 245 cm --Pig Alley
1560 meters -6, Trace in 12 Hrs, 24 cm in 24 Hrs, Base 167 cm--Catskinner

660 meters -2, Valley Temp, Max temp Yesterday was +1.0, 11.2 mm of precip yesterday.

As of 07:00 Hrs this am we have overcast skies and variable visibility. Snowing very lightly.

FORECAST:

A short lived break early this am before a warm front arrives on shore with light precip in a Westerly flow aloft. A trailing cold front will bring moderate precip by this afternoon with the FL rising from surface to around 1000 meters with strong winds. Wednesday will be unsettled with mostly overcast skies with some sunny breaks. Thursday will see a weak shortwave ridge build with mostly unsettled weather, mix of sun and cloud. Yet another weak front arrives Friday with some periods of light precip but mostly dry unsettled weather with a good chance of a few breaks. Next significant front will arrive next Tuesday. Guesstimates: 25-35 cm by Wednesday am, 1-3 cm by Thursday am, 0 cm by Friday am, 4-5 cm by Saturday am.

GOES IR image from this am.

A strong Pacific front will bring lots of snow and strong winds for this Tuesday.

Unsettled Wednesday with mostly cloudy skies, FL should drop to surface.

Ridging to the East but low will send some cloud our way for Thursday. Periods of sun.

AVALANCHE ACTIVITY:

Max Gust yesterday at 2180 meters was 126 KPH at 06:30 Hrs.

AC on Whistler produced Sz 1-1.5 Xl, Xt, Xe, Xc, Sc. A few Sz 2's.

Max gust yesterday at 2240 m was 134 KPH at 06:15 Hrs.

AC on Blackcomb yesterday produced Sz 1-2.

From Sea to Sky Avalanche Advisory:

Avalanche Summary

A large, natural storm slab avalanche cycle size 3-4 occurred near Pemberton over the weekend. Natural and explosive triggered storm slabs size 1-2 were reported elsewhere. This MIN report from Friday illustrates the active avalanche conditions during this storm.

Persistent slab avalanche activity has tapered significantly since the cycle early last week, but persistent slabs size 2-2.5 were still triggerable by explosives on weekend. Events from last week include:

A fatal avalanche in the South Coast Inland region (near the Sea to Sky boundary) north of Pemberton in the Railroad Pass area last Monday. It was reported to be a size 2 persistent slab avalanche on a west aspect, around 1650 m. The RCMP press release can be viewed here, and the Avalanche Canada report can be found here.
A size 2.5 avalanche was triggered on Monday by a skier on Rainbow Mountain, which resulted in a full burial and, thankfully, a successful rescue. The avalanche failed on a 60 cm deep crust and facet layer on a northeast aspect around 1800 m.

These avalanches highlight the ongoing potential to trigger persistent weak layers in the snowpack.

Snowpack Summary

Over 100 cm of recent storm snow has seen extensive wind effect at upper elevations, with scoured windward aspects, wind slabs in lee features and growing cornices at ridgetop.

The snowpack is currently quite complex. The layer of greatest concern is a melt-freeze crust from early December, found around 100-200 cm deep in the snowpack. This crust may have surface hoar or sugary faceted grains sitting above it. There have been several recent large natural and human triggered avalanches on this layer and new snow loads as well as large loads from storm slab avalanches have potential to trigger these layers.

INFORMATION & OBSERVATIONS: