YESTERDAY:
Unsettled early Saturday morning.2240 meters -6, Winds were 50-65 KPH S--Horstman Hut
1860 meters -4, Winds were 30-45 KPH SE --Rendezvous
1570 meters -3, 5 cm in 12 Hrs, 6 cm in 24 Hrs, Base 184 cm--Catskinner
FORECAST:
An approaching warm front will bring periods of light-heavy precip in a Westerly flow aloft. The FL is expected to top out at 1500 meters. Strong alpine winds will reach or exceed 100 KPH. Another warm front with a trailing cold front on Monday after a short lived dry out Monday morning. . The FL should drop to surface by Monday night. Periods of light precip expected on Monday, should ease to flurries by Monday afternoon and dry out into Tuesday. Unsettled weather Tuesday with a mixed bag. Some weak ridging will bring some sunny breaks and flurries. Wednesday is also looking unsettled at this time. Guesstimates: 20-30 cm by Monday am, 2-6 cm by Tuesday am, 1-3 cm by Wednesday am.
AVALANCHE ACTIVITY:
Update on the avalanche that killed a snowboarder in Wyoming. Article below. Net PicFrom the Sea to Sky Avalanche Advisory:
Avalanche Summary
The main story on Sunday will be new storm and wind slabs with the incoming storm.
A small 15 cm storm on Friday resulted in in several small (size 1) human triggered storm and wind slabs, with explosive control producing some larger (size 2) avalanches on bigger terrain features.
There was some notable avalanche activity a week ago after a bout of northerly winds formed wind slabs in unusual places (eg. south, southeast, and southwest facing slopes). 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 old 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
Forecast snowfall amounts are variable across the region with 40 cm expected in coastal areas like Squamish and the Sunshine Coast and closer to 20 cm further inland near Whistler and Pemberton. The new snow and wind will form reactive slabs at all elevations, while rain could be expected up to 1400 m.
The new snow adds to 15 cm of recent snow sitting above a potentially reactive interface consisting of surface hoar layer at treeline, a crust below 1800 m, sun crusts on steep south slopes, and faceted surfaces in the alpine. These interfaces could be failure layers during the storm.
A lingering persistent weak layer from late January is 80-120 cm deep and consists of facets at upper elevations and surface hoar in sheltered areas. Although this structure is suspect, we have no recent reports of avalanches on this layer.
INFORMATION & OBSERVATIONS:
It is very easy to find yourself in a touchy situation. Would only take a Sz 1 to mess up the day.FROM SEA TO SKY MIN REPORTS:
Flute Cruiser: Feb 20, 2021
Crusty on the Duffey: Feb 20, 2021
Rohr Ridge-Rocky Horror: Feb 20, 2021
Saxifrage E2: Feb 20, 2021
VIDEOS:
Massive Na Mt Blackmore: Montana
Powder Picker Feb 20, 2021: David Jones
ARTICLES:
Two avalanche fatalities reported in Northern Wyoming this week: Bridger-Teton Avalanche Center
Update on the avalanche that killed a snowmobiler in Wyoming: CAIC
Update on the avalanche that killed a snowboarder in Wyoming: CAIC
Snowmobilers witness large destructive avalanche in the Beaverhead Mountains: Colorado
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