Avalanche Forecast
Issued: Mar 8th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
The alpine is the most likely place to encounter triggerable wind slabs and a tricky persistent slab problem that has produced large, deep and surprising avalanches recently. Seek out sheltered treeline terrain in side valleys for the best and safest riding.
Summary
Confidence
Avalanche Summary
On Tuesday, a size 2.5 persistent slab avalanche was remotely triggered by skiers on a ridgetop in the alpine. The slab propagated widely on a thin, rocky southeast aspect and it stepped down to basal facets lower on the slope.
On Friday, our field team observed natural wind slab avalanches up to size 2 and loose snow sluffing from steep alpine terrain around the White Pass.
Snowpack Summary
Outflow winds from the north have done a real number on the surface snow scouring exposed terrain, creating waves of sastrugi in more sheltered terrain, and forming wind slabs on southerly aspects. Very sheltered terrain in side valleys to the east and west of White Pass still harbour softer snow for riding.
The middle of the snowpack is very firm and settled. There is a surface hoar layer buried 60 cm (Powder Valley, Tuthsi, Paddy Peak) to 120 cm (White Pass) deep in sheltered, mostly north facing terrain features that produced some large, human-triggered avalanches in January and February.
At the base of the snowpack large sugary crystals persist.
Weather Summary
Wednesday night
Clear. Moderate northeasterly outflow wind. Alpine low -20 ˚C.
Thursday
Increasing cloud with flurries bringing a few cm of snow. Light to moderate northeasterly wind. Alpine inversion with a high of -10 ˚C at 1800 m.
Friday
Up to 5 cm overnight then light flurries in the morning and a mix of sun and cloud in the afternoon. Moderate to strong northeasterly wind. Alpine high -16 ˚C.
Saturday
A mix of sun and cloud. Moderate to strong northeasterly wind. Alpine high -20 ˚C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Northerly winds continue to transport what loose snow is left into windslabs.
Aspects: South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar and/or a crust buried about 100 cm deep have produced large, widely propagating avalanches in the alpine as recently as Tuesday. These avalanches have been observed on north and south aspects and some have been remotely triggered by riders.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 9th, 2023 4:00PM
