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Avalanche Forecast

Mar 28th, 2018–Mar 29th, 2018
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
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
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.

Wind slabs have recently formed in the alpine and tree line elevation bands. They may be most reactive on shady aspects.

Confidence

High -

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 Monday reports 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.Saturday we received reports of a natural avalanche cycle from size 2-3 that occurred during the storm in wind loaded and cross-loaded alpine terrain, as well as numerous reports of large (size 2) skier and sled triggered storm slabs including several size 1-2.5's remotely triggered from a distance. These avalanches are suspected to have failed on the recently buried (March 21st) surface hoar/crust layer. Read details of a personal account here.

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. 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.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2