Avalog Join
Archived

Avalanche Forecast

Mar 8th, 2016–Mar 9th, 2016
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
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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

Regions: Sea To Sky.

Danger could rise sooner than indicated if we see more than 10 cm of new snow (with wind) before the end of the day on Wednesday.

Confidence

Moderate

Weather Forecast

WEDNESDAY: Mainly cloudy with snow developing late in the day. The freezing level should be around 1500 but will rise to 1800 m overnight. Ridge winds increase to strong or extreme from the SW-SE with the arrival of the storm. THURSDAY: Periods of snow – 40-70 cm Wednesday night through Thursday. The freezing level drops to around 1400 m and winds are moderate to strong from the south. FRIDAY: Cloudy with sunny breaks. The freezing level could rise to 1800 m during the day and winds ease to light.

Avalanche Summary

We've had reports of skier and explosive controlled avalanches up to size 2 (mostly size 1-1.5) each day for the past few days. Most of these have involved only the most recent snowfall (~24 hours) and were limited to steep wind-loaded slopes. On Sunday a loose dry sluff triggered a size 3 wet slab at 1400 m. This slide released on the mid-Feb crust. On Saturday there was evidence of widespread natural storm slab avalanche activity to size 3.5. The avalanches failed in response to heavy storm loading on Friday and possibly warming on Saturday.

Snowpack Summary

Storm totals from the past week were well over 100cm with more currently falling and much more on the way. Previous strong S-SW winds have shifted the new snow into deeper slabs on lee and cross-loaded alpine and treeline features. With the exception of shady alpine slopes, 30-50 cm of storm snow overlies a melt-freeze crust that formed on Sunday from high freezing levels and sun. Ongoing stormy weather has also encouraged extensive cornice growth. Weaknesses below the recent storm snow are expected to have gained considerable strength while the mid and lower snowpack are also strong and well-settled.

Avalanche Problems

Storm Slabs

Expect lingering storm snow instabilities and touchy pockets of wind slab in steep lee terrain. This problem will increase with the storm arriving late on Wednesday. 
Be cautious as you transition into wind affected terrain.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Cornices

Cornices are reported to be huge and weak. Stay well back from ridge crests, and watch your overhead hazard.
Do not travel on slopes that are exposed to cornices overhead.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4