Wind Slabs
N
NE
E
SE
S
SW
W
NW
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible - Likely
- Dimensione
- 1–2
Wind will impact flurries and redistribute loose snow. Look for fresh wind slabs loading lee features.
Bollettino valanghe
Vedi sulla mappaPurcells
Mar 23 – 24, 2021Avalanche Canada
Archiviato · scaduto 6 years ago
Pericolo valanghe
Thu
Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
In sintesi
Look for cold dry snow on north facing terrain at upper elevations. Be wary as this may also be where wind slabs develop.
Problemi valanghivi
Cornices
NNEESESSWWNW- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 1.5–2.5
Where cornices exist they pose a threat both from the potential to collapse under your feet (or machine) and from the potential to send large chunks of snow far down a slope. If anything can trigger the more stubborn persistent weak layers it's a large falling cornice.
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
TUESDAY NIGHT: Partly cloudy and unsettled with flurries, trace to 5 cm. Moderate west wind, alpine low -12C, and freezing level valley bottom.
WEDNESDAY: Cloudy with flurries, up to 10 cm accumlation. Moderate southwest wind decreasing through the day, alpine high -3C, and freezing level rising to 1500 m.
THURSDAY: Unsettled with flurries, 5 cm. Light west wind, alpine high 0C, and freezing level rising above 1500 m.
FRIDAY: Sunny breaks and unsettled with flurries, trace to 5 cm. Moderate west wind, alpine high 0C, and freezing level rising above 1500 m.
Avalanche Summary
No avalanches reported Monday.
On Sunday, dry loose avalanches failed naturally and were reactive to skiers with fresh low density snow sliding on crusts or compact surfaces.
On Saturday, several natural size 1.5 wind slabs were observed on northeasterly aspects in the alpine. Size 2 slab avalanches were reported failing naturally on steep, south slopes (MIN report and deeper snowpack here). Sluffing and dry-loose avalanches were reported in steep terrain.
A few small loose wet avalanches were reported Wednesday through Friday on solar aspects into the alpine. A small wind slab was also reported from a high elevation east facing aspect last Thursday.
Snowpack Summary
Southwesterly winds and flurries will form fresh slabs in lee features. 20-40 cm recent snow covers dry and compacted snow on polar surfaces above 1800 m and crusts on solar slopes. Storm snow has been sluffing easily on the crust. Large cornices loom over alpine ridgetops. Spring temperatures and sun are producing a melt-freeze snowpack below 1300 m and higher on solar slopes.
A persistent weak layer of facets 40-60 cm deep that was buried in mid-February was reactive in the north of the region earlier this month but since the first week of March, only a couple of avalanches have been reported on this layer resulting from large triggers such as cornice fall. There are several other weak layers deeper in the snowpack composed of old surface hoar, facets and/or crusts, all of which have been recently unreactive.
Terrain and Travel
- Be alert to conditions that change with elevation, aspect and exposure to wind.
- Carefully evaluate steep lines for wind slabs.
- Minimize your exposure time below cornices.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.