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Avalanche Forecast

Apr 4th, 2017–Apr 5th, 2017
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
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: Sea To Sky.

Back into a stormy pattern leading into the weekend. Expect to see the avalanche danger gradually rise over the coming days as snowfall amounts begin to accumulate.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Wednesday

Weather Forecast

WEDNESDAY: Periods of snow, accumulation Tuesday night into Wednesday 10-20cm / Moderate south wind / Alpine temperature -1 / Freezing level 1500 m THURSDAY: Periods of snow, accumulation 10-15cm / moderate to strong south wind / Alpine temperature -1 / Freezing level 1500mFRIDAY: Flurries, accumulation 5cm / Light to moderate east wind / Alpine temperature -1 / Freezing level 1500m

Avalanche Summary

On Monday numerous natural loose wet avalanches up to size 1.5 were observed on southeast through west aspects in steep rocky terrain. Also a few natural cornice releases to size 2.5 were observed running to the bottom of their run outs entraining loose snow only. On Sunday, a natural cornice release triggered a size 3 slab avalanche which release down 60 cm and ran to valley bottom. Skiers were triggering size 1 soft slabs in wind loaded features. On Wednesday, expect newly formed wind and storm slabs to be reactive to human triggering. These slabs are expected to be particularly touchy where they overlie a melt-freeze crust.

Snowpack Summary

Widespread melt-freeze conditions are expected on all aspects and elevations except for high elevation north facing terrain. On all aspects below around 2000 m and higher on sun exposed slopes, there may be multiple crust layers in the upper snowpack including the late-March rain crust which is now typically down 60-80 cm. Expect to see another 10-20cm of new snow from Tuesday night sitting on the old snow surfaces above the 1300m elevation band. Moderate alpine wind from the south will have redistributed this new snow and formed additional wind slabs in the alpine and at tree line which may overlie a crust. Large cornices exist primarily on north aspects in the alpine.

Avalanche Problems

Wind Slabs

Wind slabs have recently formed in north facing terrain at higher elevations and are expected to remain reactive to human triggering on Tuesday.
Use ridges or ribs to avoid pockets of wind loaded snow.Use extra caution on steep open slopes and unsupported convex rolls.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Cornices

Large cornices may become weak with daytime warming or during periods of stormy weather.
Give cornices a wide berth when traveling on ridgesEven small cornice falls may trigger larger avalanches on slopes belowAvoid exposure to slopes that have cornices overhead

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3