Wayne Flann Avalanche Blog: January 4, 2021

YESTERDAY:

Over the past 7 days we have received 151 cm of snowfall at 1650 meters.

Awesome turns in the alpine.

Powder to the People!!

Challenging to get the terrain open. More snow on Whistler--More Hazard.

As of 14:00 Hrs yesterday Catskinner weather plot had 155 cm base.

Mix-rain and snow showers yesterday. Over the past week 78.1 mm recorded at 660 meters.

As of 14:00 Hrs Sunday Jan 3, 2021. -5 with a 20-50 KPH South wind. +1 in the valley.

Goes Image from the same timeframe.

Just before dusk looking North. -6 with a 20-35 KPH SE wind.

Weather Observations for January 4, 2021 taken at 06:00 Hours.

2240 meters -4, Winds were 95-130 KPH E--Horstman Hut

2180 meters -4, Winds were 95-120 KPH E--Whistler Peak
1860 meters -3, Winds were 30-50 KPH SE --Rendezvous

1835 meters -3, Winds were 25-55 KPH ESE--Round House

1650 meters -1, 14 cm in 12 Hrs, 17 cm in 24 Hrs, Base 239 cm --Pig Alley
1560 meters -3, 14 cm in 12 Hrs, 16 cm in 24 Hrs, Base 158 cm--Catskinner

660 meters 0, Valley Temp, Max temp Yesterday was +2.3, 1.2 mm of precip yesterday.

As of 07:00 Hrs this am we have obscured skies, limited visibility and snowing 2 cm/ hr.

FORECAST:

Warm front and trailing cold front will push through this am with steady light-moderate precip in a South Westerly flow aloft. The FL will hover in the 1000 meter range, possibly going to 1500 meters with strong winds. Precip will ease later this afternoon drying out into Early Tuesday am when another active front brings light to moderate precip to the area. A broad trough will bring mostly overcast skies for Wednesday with periods of light precip. A weak short lived ridge builds for Thursday with unsettled weather. A series of fronts will push through Friday -Tuesday with Monday being a significant storm day. Guesstimates: 18-22 cm by Tuesday am, 30-40 cm by Wednesday am, 0 cm by Thursday am, 12-16 cm by Friday am.

GOES IR image from this am.

Low will send light to moderate precip today, FL should hover around 1000 m.

More active front for Tuesday with slightly warmer temps.

Weak frontal band for Wednesday with some periods of light precip, FL 1000m to surface.

Some precip for Wednesday. afternoon.

AVALANCHE ACTIVITY:

Limited AC on Whistler. Some Sz 1 Xe Sc, evidence of Sz 2-2.5 Na.

AC on Blackcomb produced Sz 1-1.5 ssl Xe, Sc. Sz2 Xt Sz 2.5 Xl on Dec 09 Crust.

Local Snow Bikers remembered for their adventurous spirit, article below. Net Pic

Looking for the best avalanche shot from now to January 17, 2021. A pair of goggles to who gets the best image. Submit to wwflann@me.com.

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.

Explosive triggered persistent slab avalanches size 2-2.5 were reported Sunday. Several large natural and human triggered persistent slab avalanches occurred early last week:

There was 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 that resulted in two fatalities. 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.
A natural size 3 persistent slab avalanche was reported on Mount MacBeth on Monday, check out this MIN report for details of this observation.

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

Snowpack Summary

10-30 cm of new snow between Sunday night and Monday afternoon and strong southwest wind, continue to build widespread storm slabs. Recent storm totals are well over 100 cm.

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: