Wayne Flann Avalanche Blog: February 16, 2021

YESTERDAY:

08:30 hrs, unsettled with some flurries. -5 with a 0-5 SSW breeze at 1860 m.

Snowing lightly in the morning. 5 cm of new recorded by 14:30 Hrs at 1570 meters.

It was certainly family day on the hill.

Awesome blown in powder.

Visibility was challenging at times.

Good at other times.

There were some nice turns to be had. Sunny breaks in the afternoon.

Monday Feb 15, 2021. 14:00 Hrs. -4 with a 5-10 KPH SW wind. -2 in the valley.

Satellite image from Monday afternoon.

Certainly a mixed weather bag.

Unsettled.

Kids these days, all about the air time.

Weather Observations for February 16, 2021 taken at 06:00 Hours.

2240 meters -9, Winds were 10-20 KPH WSW--Horstman Hut

2180 meters -9, Winds were 20-25 KPH WSW--Whistler Peak
1860 meters -7, Winds were 0-5 KPH S --Rendezvous

1835 meters -7, Winds were 10-20 KPH SSW--Round House

1650 meters -5, 2 cm in 12 Hrs, 6 cm in 24 Hrs, Base 243 cm --Pig Alley
1570 meters -5, 2 cm in 12 Hrs, 7 cm in 24 Hrs, Base 180 cm--Catskinner

660 meters -4, Valley Temp, Max temp Yesterday was 0, 3.8 mm of precip yesterday.

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

FORECAST:

Unsettled weather for today with a few flurries this am in a Northwest flow aloft. Should see a mix of sun and cloud by later this am with the FL possibly rising to 900 meters, dropping back down th surface tonight. Ridge strengthens on Wednesday with sunny skies and seasonable temperatures. An upper trough moves down the coast for Thursday with light snow into Friday. A series of frontal bands will give us snow into Monday of next week. Guesstimates: 0-1 cm by Wednesday am, 0 cm by Thursday am, 5-10 cm by Friday am, 3-6 cm by Saturday am.

GOES IR image from this am.

Ridge will start moving on shore with unsettled weather for today.

Northwest flow aloft.

Ridge strengthens for Wednesday, should see sunny skies.

Upper trough for Thursday with seasonal temps.

Low moves down the coast on Thursday.

AVALANCHE ACTIVITY:

Sz 2 Sa above the top of Cloud Nine in 7th Heaven. Monday afternoon.

Crown 20-100 cm, 30 m wide, ran 220 m. Sz 2 stiff slab. Went to ground on Basal facets.

Determined there was no involvement. Confirmed with person who set it off. Good practice.

Sign Line into Lakeside.

Wet loose Sz 1 in Lakeside. Avalanche Closure. Snow in lakeside moist on the surface. Next Mfcr.

Wet loose in Lakeside. Sun warmed the snow up very quickly.

Na Sz 2 in Corona Bowl.

Dry loose in Emerald Bowl.

Cool how it slowed down.

Sz 1-2 Na wind slabs. Very active cycle Monday afternoon below Bony Basin..

Na Sz 1's on Triplex.

Sz 1's dry loose.

Below Spearhead Peak. Did I say it was very active and widespread.

Stiff slabs on some aspects.

An avalanche has killed a ski tourer in the Giant Mountains, Czech Republic. Article below. Net Pic

An avalanche has killed a ski tourer on Mont Tabor, France. Article below. Net Pic

Avalanche mitigation on Whistler yesterday produced some Sz 1 Xe Sc. Na activity observed.

Avalanche Summary from Sea to Sky Bulletin:

Avalanche Summary

Sunday was a much quieter day for avalanche activity. Avalanche control work produced very small avalanches with the exception being a single size 2.

Another fatal avalanche involvement occurred in the region on Saturday in the Brandywine valley. The person caught was carried several hundred metres over steep, rugged terrain and through treed slopes below. The avalanche is described as a size 1 (small) wind slab on a southwest aspect at 1700 metres. The incident report can be seen here.

On Friday, a large (size 2.5), fatal avalanche was triggered by skiers at 2200 metres on a west-facing slope on Phalanx Mountain. The avalanche is described as a wind slab that formed to the lee of recent strong east winds. Two people out of a group of three were involved in the avalanche and one person was killed. The incident report can be seen here. A second, smaller (size 1.5) wind slab was triggered by skiers on a nearby slope, again causing injury to the person involved.

A bout of strong northerly winds on Thursday caused conditions in the region to change rapidly, with new and touchy wind slabs forming in unusual places. Numerous natural releases from size 1 to size 2 were observed in the Whistler area above about 1900 metres on and since Thursday.

It is important to note wind has not affected elevation bands uniformly across the region, with heavy wind effect and slab formation noted even below treeline in some areas. This is a critical piece of information as new snow obscures existing wind slab formations.

Two more skiers were involved in an avalanche in the Supercouloir feature of Mamquam Mountain on Thursday. This avalanche was a natural wind slab release and again resulted in serious injuries and an urgent evacuation by helicopter.

Snowpack Summary

As of Monday afternoon, 5 to 15 cm of new snow has accumulated with moderate southeast wind. This adds to the existing wind slab problems brought on by powerful east and northeast winds that have been redistributing loose snow into wind slabs. Winds have been circling the compass expanding problems to all aspects. The images in this MIN from Rainbow show the extensive wind effected snow.

Monday's snow adds to the 15 cm of older low density snow that can be found in shaded, sheltered areas and to more widespread wind-affected snow. This previous surface has been transforming into weak, faceted grains under recent cold temperatures. On solar aspects, a thin sun crust may be found near the new snow interface or beneath recently wind transported snow. Both of these interface types are contributing to the reactivity of new wind slabs.

Below the evolving surface, 50-100 cm of settled storm snow sits on a persistent weak layer from late January that consists of facets at upper elevations, surface hoar in sheltered areas, a melt-freeze crust below 1900 m, and a sun crust on south-facing slopes. There could be more than 100 cm on this layer in wind loaded areas. Although this structure is suspect, we have no recent reports of avalanches failing at this interface within the region.

A crust from early December, currently considered dormant, may be found around 200+ cm deep in the snowpack.

INFORMATION & OBSERVATIONS:

Amazing how snow can cling onto the rock.