Avalanche Forecast
Issued: Apr 5th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices and Wind Slabs.
swerner,
Avalanche Canada
Periods of sunshine can pack a punch and trigger natural avalanches and cornice fall. Give cornices a wide berth from above and below.
Pockets of wind slab may exist and be reactive to human triggering on leeward features in the alpine.
Summary
Confidence
Weather Forecast
The region will start to see the effects of the next frontal system by Tuesday night. This will bring moderate snow amounts accompanied by strong southwest wind.
Tuesday: Mix of sun and cloud. Ridgetop wind strong from the southwest. Alpine temperatures near -3 and freezing levels 1600 m.
Wednesday: Snow 10-20 cm. Ridgetop wind moderate to strong from the southwest. Alpine temperatures -3 and freezing levels 1400 m.
Thursday: Mix of sun and cloud with a trace of new snow. Ridgetop wind light from the southwest. Alpine temperatures near -4 and freezing lvels 1400 m.
Avalanche Summary
On Monday a size 3 natural wind slab was reported on a North aspect at 2400 m.
Large (size 2-3) natural cornice failures have been reported recently, one on Sunday triggered a 30 cm deep storm slab.
A bit of cloud cover and a strong southwest wind is expected to keep snow surfaces cool on Tuesday. Natural avalanche activity may taper. However; things can change rapidly when the sun shines. Natural avalanche activity and cornice failures could then spike.
Snowpack Summary
10-30 cm of recent snow accompanied by strong southwest wind may have formed wind slabs on leeward slopes at upper elevations. Reports indicate the snow is bonding to the underlying surfaces which include wind-affected snow in the alpine or crust on solar aspects and below 1900 m. Below this elevation and on solar aspects the new snow dusts crusty surfaces down to 1500 m. Below 1500 m, the moist snowpack is quickly diminishing.
At alpine and treeline elevations, a widespread crust exists (except on north-facing slopes above 1800 m) buried 50-100 cm deep. Overall the snow seems to be bonding well at this interface, although there have been a few isolated avalanches running on deeper crust layers over the past few weeks.
Terrain and Travel
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Use ridges or ribs to avoid areas of wind loaded snow.
- Be alert to conditions that change with elevation and sun exposure.
Problems
Cornices
Cornices become weak with daytime warming. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
Wind slabs will be most likely be isolated to immediate lees of ridgecrests and roll-overs in wind exposed alpine terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 6th, 2021 4:00PM
