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Archived

Avalanche Forecast

Mar 28th, 2018–Mar 29th, 2018
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

In light of significant avalanche activity the forecast has been updated 8:30 March 29, 2018. Caution on shady aspects in the alpine and tree line elevation where a persistent weak layer may be reactive.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

THURSDAY: Flurries, accumulation 5-10cm / Moderate to strong southwest wind / Alpine temperature -4 / Freezing level 1300 m. FRIDAY: Cloudy with isolated flurries / Moderate west wind / Alpine temperature -4 / Freezing level 1400m SATURDAY: Cloudy with sunny periods / Light southeast wind / Alpine temperature -2 / Freezing level 1500m

Avalanche Summary

On Tuesday there was a size 1 avalanche that sympathetically triggered a size 3 persistent slab avalanche resulting in a burial. This was on a northeast aspect at 2000m, 50cm deep. Additionally there were reports of natural persistent slab avalanches size 2.5-3 on southeast through northeast aspects between 1800 and 2000m. Additionally reports on Monday show explosives and skier controlled triggered storm and wind slab avalanches to size 1.5 on north and east aspects in the alpine. On Sunday there was a report of a skier-triggered cornice failure (size 2) on a northwest aspect at 2100 m, as well as skier and sledder triggered storm slabs (size 1.5) on east and north aspects in the alpine. Explosive control work also produced cornice failures, size 2-3 with little effect on the slopes below.

Snowpack Summary

Another 5-10 cm of storm snow with strong southerly wind Sunday night adds to last week's storm which delivered 20 to 50 cm of snow accompanied by strong to extreme wind out of the southwest, south and southeast. This storm snow rests on the March 21st interface, a mix of moist grains at low elevations, crusts on solar aspects at all elevations and surface hoar/facets on north/east facing features at treeline and alpine elevations. Some west facing features may have surface hoar on top of a crust. This layer has shown to be reactive.Deeper in the snowpack, 80 to 140 cm below the surface is a combination of facets, surface hoar, and/or crust known as the mid-February layer. This interface has not been active recently.The mid and lower snowpack are strong and well settled.

Avalanche Problems

Wind Slabs

Recent new snow and strong winds have formed wind slabs in the lee of terrain features. These may be most reactive where they may be sitting on a thin and weak layer of facetted crystals on shady aspects.
Extra caution needed around cornices with current conditions.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

A weak layer of surface hoar or facetted crystals has become reactive especially where it may be sitting on a hard crust.
Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for wide propagations.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3