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Archived

Avalanche Forecast

Mar 19th, 2013–Mar 20th, 2013
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

The main concern today is storm snow slabbing up.  Sunny skies and strong solar radiation could result in increased avalanche activity.  Tomorrow a strong system is expected to bring more snow and loading to the area.

Weather Forecast

An upper ridge will build over the province today, bringing dry but windy conditions.  Freezing levels will rise to 1500m, and solar radiation will become a factor.  Another low will move into the area on Wednesday bringing moderate to heavy precipitation and strong SW winds.

Snowpack Summary

Intense but intermittent flurries yesterday with locally very strong winds has added more load to the snowpack.  Up to 35 cm of snow is beginning to slab up, especially in the alpine.  Below 2000 meters, this storm snow sits on a sun crust formed on March 16.  The mid-pack remains well settled.  The Feb 12 PWL can still be found, but is stubborn.

Avalanche Summary

Numerous new slab avalanches were noted yesterday, associated with the new storm snow and strong winds, in the alpine and treeline.  Several skier triggered avalanches were triggered in the Hermit area two days ago to size 1.0. These were low density slabs sliding on a crust down 15cm with surprisingly wide propagation running far and fast.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Avalanche Problems

Storm Slabs

Convective snow flurries with strong winds yesterday added load to the storm slab problem above treeline. Below 2000 meters, a buried rain crust is providing an ideal bed surface for new snow avalanches at lower elevations.
Avoid lee and cross-loaded terrain near ridge crests.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Wind Slabs

Moderate south winds and new snow available for transport mean that you could expect windslabs on lee terrain above treeline.  Cornices are growing larger.
Avoid lee and cross-loaded terrain near ridge crests.Pay attention to overhead hazards like cornices.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

It will likely take a large trigger, like a cornice or another avalanche to trigger the surface hoar/crust layer from February 12, now down 1-1.5m. The resulting avalanche would be very large and destructive if triggered.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 4