Wayne Flann Avalanche Blog: December 27, 2020

YESTERDAY:

Looking like a winter wonderland Saturday am.

Great powder in the valley Saturday am.

It was a busy day.

Lots of fresh low density powder on Saturday!!

Another awesome day, great job on keeping the terrain open.

Fun, storm day skiing.

Saturday Dec 26, 2020. 15:00 Hrs. -4 with a 20-40 KPH East wind. +1 in the valley.

GOES IR image from the same timeframe.

Weather Observations for December 27, 2020 taken at 06:00 Hours.

2240 meters -7, Winds were 30-45 KPH SE--Horstman Hut

2180 meters -7, Winds were 25-40 KPH S--Whistler Peak
1860 meters -4, Winds were 15-30 KPH SE --Rendezvous

1835 meters -5, Winds were 10-30 KPH S--Round House

1650 meters -4, 7 cm in 12 Hrs, 14 cm in 24 Hrs, Base 158 cm --Pig Alley
1560 meters -4, 6 cm in 12 Hrs, 15 cm in 24 Hrs, Base 100 cm--Catskinner

660 meters 0, Valley Temp, Max temp Yesterday was +1.7, 5.6 mm of precip yesterday.

As of 07:00 Hrs this am we have obscured skies, limited visibility and it is snowing.

FORECAST:

A weak warm front brushes the area today in a Southerly flow aloft. Unsettled weather for this afternoon as a ridge begins to build in the area for Monday. The FL will hover in the 1000 m range for today. Some discrepancies in the models, ridge is supposed to build but feel there is a chance of some precip later today with the low brushing by as it heads South. Could be wrong but time will tell. Mostly sunny skies for Monday as the ridge strengthens. Unsettled into Tuesday afternoon with a weak front arriving Tuesday night into Wednesday. More light snow for Thursday with the potential for a real storm to arrive Friday into Saturday. Guesstimates: 5-15 cm by Monday morning, 0 cm by Tuesday morning, 6-12 cm by Wednesday am.

GOES IR image from this am.

Low to the SW may have some influence today, high is building.

High builds for Monday with mostly sunny skies.

Unsettled for Tuesday am, with more weather moving in by Tuesday night.

Low will bring a weak front by Tuesday evening.

AVALANCHE ACTIVITY:

Avalanches have killed 10 climbers in the Alborz Mtns, Iran. Article below. Net Pic

Avalanche control on Dec 23, 2020. Hwy 1. Article below. BC Highways Pic

Avalanche control on Blackcomb produced Sz 1 storm slabs Sc on Saturday.

Avalanche control on Whistler produced mostly Sz 1 soft slabs Xe, Xc, Sc. 1 Sz 2 wind slab Xe.

From the Sea to Sky Advisory:

Avalanche Summary

Storm slabs and cornices were reported to be touchy during the storm on Saturday, skier end explosive control work producing storm slab avalanches size 1-2. Earlier this week, numerous wind slab avalanches were reported, triggered naturally and by riders at treeline and alpine elevations.

A few large avalanches have been observed over the past week, running on buried weak layers (described in snowpack summary). Most occurred on north to east aspects in the alpine. A size 2.5 reported Thursday from a coastal glaciated area west of the Squamish river. It was on a southeast aspect, 100 m wide with crown depth 40-80 cm deep.

Snowpack Summary

15-30 cm of recent snow has been redistributed by strong easterly winds, depositing deep pockets of storm slab into lee terrain features.

Two potential concerning weak layers may be present in the snowpack:

The shallower layer, around 60 to 100 cm deep, includes feathery surface hoar crystals. This layer may be found in sheltered terrain features at treeline and lower alpine elevations but has been reported as spotty across the region.
The more widespread weak layer includes sugary faceted grains that overlies a hard melt-freeze crust. This layer ranges in depth from 10 cm to 120 cm due to the wind scouring and loading the snow in different terrain features over the past two weeks. The layer has been reported as being widespread up to around 2000 to 2200 m.

To date we have mostly seen sporadic avalanche activity on these layers, but they remain possible to trigger where they exist in the mountains.

The remainder of the snowpack is well-settled.

INFORMATION & OBSERVATIONS: