Avalanche Forecast

Issued: Apr 16th, 2013 10:37AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Cornices.

mpeter, Avalanche Canada

South Coast.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Wednesday: Expect clouds to build through the day with alpine temperatures reaching -5 and winds turning to moderate southwesterlies. Freezing levels could reach 1500m. Isolated flurries are possible, with limited accumulations.Thursday: Cloudy skies with temperatures reaching -2 and freezing levels climbing to 1800m. Expect light westerly winds and a chance of isolated flurries.Friday: Expect continued unsettled skies with more isolated flurries, temperatures around -2 and light westerly winds.

Avalanche Summary

Numerous rider triggered and isolated remote/sympathetic events have been reported in high (2400-2700m) north and northeast facing slopes up to size 2.0, all associated with preserved surface hoar.

Snowpack Summary

Recent convective snowshowers (Thursday to Sunday) have given up to 45cm of new snow at higher elevations. The surface snow has been going moist on all aspects up to 2000m and higher on solar aspects due to strong solar inputs. The new snow interfaces are predominantly crusts (sun, wind, meltfreeze) and the bonds within this storm snow are slowly tightening.50-75cm below the surface you will find a melt-freeze crust from previous sunny weather. At the same interface, spotty surface hoar is still being reported (up to 20mm!) in some high, north facing slopes. Where the surface hoar is present, consistent sudden results have been observed. Isolated sudden results have also been reported on the crust interface (South through East aspects, 2000-2300m), where some facetting has occurred.Cornices are huge and may act as a large trigger on slopes below.

Problems

Wind Slabs

New windslabs have formed in immediate lee locations and the bonds with the underlying crusts may be suspect. In specific terrain avalanches have been stepping down to a persistent surface hoar layer buried last week.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Cornices

Recent snow and wind has added mass to existing cornices. Cornices can act as a large trigger to deeper weaknesses.

Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Apr 17th, 2013 2:00PM