Wayne Flann Avalanche Blog: February 20, 2021

YESTERDAY:

First lift up Friday morning.

Unsettled weather Friday.

Some patches of blue in the am.

Always good turns to be had somewhere!!

Did I say the skiing was pretty sweet Friday.

Visibility was ok!

Skiing by the rock is always fun on bad vis days.

Too the Blue!! Some breaks.

Unsettled weather but at times it was snowing & blowing.

Friday Feb 19, 2021. 17:00 Hrs. -7 with a 10-25 KPH ESE wind. +1 in the valley.

Weather Observations for February 20, 2021 taken at 06:00 Hours.

2240 meters -11, Winds were 10-20 KPH S--Horstman Hut

2180 meters -11, Winds were 40-45 KPH S--Whistler Peak
1860 meters -9, Winds were 15-25 KPH ESE --Rendezvous

1835 meters -8, Winds were 20-40 KPH SE--Round House

1650 meters -7, 3 cm in 12 Hrs, 3 cm in 24 Hrs, Base 248 cm --Pig Alley
1570 meters -6, 1 cm in 12 Hrs, 1 cm in 24 Hrs, Base 183 cm--Catskinner

660 meters 0, Valley Temp, Max temp Yesterday was +2.1, 3.2 mm of precip yesterday.

As of 07:00 Hrs we have broken cloud, unlimited visibility and it is snowing lightly..

FORECAST:

The weak upper trough will bring overcast skies this am with some scattered flurries ending this am. There are a few breaks in the mix as well. A warm front will arrive sometime this afternoon with light precipitation in a North Westerly flow aloft. The FL will hover around or slightly above surface. By Sunday the atmospheric river event will bring warming temps, strong winds and moderate to heavy precip. Still thinking the FL will remain below 1500 meters. The most intense precip will arrive Sunday afternoon into the night. By Monday the precip will ease to showers in the early hours of the day. Should see a break with dry cloudy conditions before a cold front arrives later in the am. Brief impulse of precip with a drying trend and cooler temps by Monday evening. At this time it looks unsettled for Tuesday with seasonal temps and some periods of light precip. Guesstimates: 8-12 cm by Sunday am, 20-30 cm by Monday am, 2-4 cm by Tuesday am, trace-1cm by Wednesday am.

GOES IR image from this am.

Warm front arrives this afternoon, the FL looks good for today.

North Westerly flow aloft.

Wet, warm, and windy for Sunday.

Low will send some precip for Monday with more seasonal temps by the afternoon.

. Most of the precip heads South for Monday.

AVALANCHE ACTIVITY:

A snowmobiler has died in an avalanche in Idaho. Smiley Creek. Article below. Net Pic

An avalanche has killed a snowboarder in Wyoming. Togwotee Mtn. Article below. Net Pic

Sa Sz 1 Cowboy Ridge Feb 19, 2021 from MIN Report below. C Watson Image

Avalanche mitigation on Whistler yesterday produced mostly Sz 1-1.5 Xe, Sc, Xc. Some Sz 2's.

Avalanche mitigation on Blackcomb produced Sz 1 Sc in steep start zones. 1 Sz Na in Lakeside.

Cornice separation.

Slabs had formed.

Firm slabs on Friday.

From the Sea to Sky Advisory:

Avalanche Summary

New wind slabs were reactive on Friday, with reports of size 1 human triggered avalanches on smaller slopes and size 2 natural and explosive triggered avalanches on bigger slopes. Between Tuesday and Thursday there were several small (size 1-1.5) human-triggered wind slab avalanches, as well as some dry loose and wet loose avalanches in steep terrain.

There was some notable avalanche activity towards the end of last week and last weekend, as a bout of strong northerly winds formed large wind slabs in unusual places (eg. south, southeast, and southwest facing slopes). This created a tricky problem that resulted in a string of serious avalanche accidents. On Feb 11 two skiers were caught in a natural wind slab avalanche in a couloir on Mamquam Mountain, resulting in serious injuries. On Feb 12, a fatal avalanche was triggered by skiers at 2200 m on a west-facing slope on Phalanx Mountain (a size 2.5 wind slab). On Feb 12, another fatal avalanche was triggered by skiers at 1700 m on a treed southwest-facing slope in the Brandywine valley (a size 1 wind slab). See the incident reports here and here for details. These wind slabs have decreased in reactivity over the past the week, however may still present as a problem with the stress of new snow and wind.

Snowpack Summary

As of Friday afternoon there is 10-20 cm of new snow above a widespread interface that may become a reactive failure layer for storm and wind slab avalanches over the weekend. This interface consists of a surface hoar layer at treeline, a crust below 1800 m, sun crusts on steep south slopes, and faceted surfaces and hard wind slabs in the alpine. Below the evolving surface, 80-120 cm sits on a lingering persistent weak layer from late January that consists of facets at upper elevations and surface hoar in sheltered areas. Although this structure is suspect, we have no recent reports of avalanches failing at this interface within the region.

INFORMATION & OBSERVATIONS:

Someone fell into a 3 meter rock hole yesterday below Pakalolo. Rescued!!!