Wayne Flann Avalanche Blog: December 19, 2020

YESTERDAY:

Sunrise Friday was at 08:07 Hrs. -4 with a 20-40 KPH East wind. +1 in the valley.

Another awesome storm skiing morning.

Lots of wind transport Friday.

There are always good turns to be had somewhere.

There was some challenging visibility at times yesterday.

Light wet snow at the Tube park at around Noon.

14:00 Hrs. -2 with a 20-90 KPH East wind. +2 in the valley.

Wet snow at 17:30 Hrs.

Weather Observations for December 19, 2020 taken at 06:00 Hours.

2240 meters -9, Winds were 20-30 KPH E--Horstman Hut

2180 meters -8, Winds were 20-35 KPH SSW--Whistler Peak
1860 meters -6, Winds were 15-30 KPH SE --Rendezvous

1835 meters -5, Winds were 10-20 KPH SW--Round House

1650 meters -6, 14 cm in 12 Hrs, 19 cm in 24 Hrs, Base 132 cm --Pig Alley
1560 meters -5, 8 cm in 12 Hrs, 14 cm in 24 Hrs, Base 88 cm--Catskinner

660 meters +1, Valley Temp, Max temp Yesterday was +3.0, 9.5 mm of precip yesterday.

If only we would have received half the precip Squamish did--45.9 mm yesterday.

As of 07:00 Hrs this am we have overcast skies and unlimited visibility.

FORECAST:

A lull this am before another frontal band arrives with light precip this morning in a Westerly flow aloft. The freezing level will hover in the 1000-1400 meter range today with a chance it might spike to 1700 meters tonight. We will see moderate precip and strong winds by this afternoon. Precip easing Sunday morning with a drying trend in the afternoon with cooler temps. Another front for Monday with the FL dropping to surface. An upper ridge builds for Tuesday with mostly sunny skies. Unsettled for Wednesday. Guesstimates: 15-25 cm above 1500 meters by Sunday am, 1-3 cm by Monday am, 12-18 cm by Tuesday am.

GOES IR image from this am.

Front arriving this morning with moderate precip by this afternoon and windy.

Cooler on Sunday with showers in the morning drying out in the afternoon.

Low will bring more snow for Monday. Cooler temps with snow to the valley.

Looking like some snow on Monday.

AVALANCHE ACTIVITY:

An avalanche has killed a sled skier at Anthracite Ridge, Colorado. Article below. CAIC Pic

Close up of the crown line. CAIC Image

Some pockets of wind slab below treeline Friday

Sz 1 storm slabs were reported yesterday. Alpine remained closed with high winds.

From Sea to Sky Avalanche Advisory:

Friday reports of a suspected widespread natural avalanche cycle to size 2 at the peak of the intense wind and precipitation. Early morning explosive control showed explosive and intentionally triggered avalanches to size 1.5 on re-loaded crusts. These windslabs were reported in lee and cross loaded features.

Thursday saw numerous explosive triggered small (size 1's) and large avalanches (size 2's) , some that released on the persistent crust layer while others were within the storm snow. One avalanche in particular illustrated how a small avalanche can step down to a known deeper layer creating a large avalanche.

On Wednesday there were reports of ongoing avalanche activity from explosive control and human triggered avalanches in the small to large range. Reports indicate varied reactivity on a buried crust layer and include an explosive controlled large avalanches (size 2-2.5) on lee sides of ridge top features near treeline. Elsewhere avalanches were small (size 1) with average crown depths of 5-15cm deep.

INFORMATION & OBSERVATIONS: