Avalanche Forecast

Issued: Apr 13th, 2018 4:01PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

mbender, Avalanche Canada

South Coast Inland.

There is uncertainty with the timing and intensity of forecast precipitation. Danger ratings are based on the high end of estimates for the south of the region.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

SATURDAY: Periods of snow overnight Friday into Saturday, accumulation 5-10cm in the north and 15-25cm in the south / Moderate to strong southwest wind / Alpine temperature -1 / Freezing level 1400 m SUNDAY: Flurries / Light to moderate west and northwest wind / Alpine temperature 0 / Freezing level 1500m MONDAY: Flurries, accumulation 5-10cm / Light west wind / Alpine temperature -2 / Freezing level 1300m

Avalanche Summary

On Monday, a MIN report from the Duffy Lake area showed a skier accidental size 2 storm slab from a north aspect at 2700 m. Please check out the report here. No new observations on Wednesday or Thursday, however information is limited this time of year. Expect the avalanche activity to increase through the forecast period with new snow and wind.

Snowpack Summary

15-30 cm of new snow overlies moist snow surfaces. At higher elevations, this overlies wind slabs formed from last weekends snow that fell with strong southwesterly winds. On ridges, cornices are reported to be large and fragile. At low elevations below treeline, recent rain has created moist or wet snow conditions.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 50 to 100 cm. This layer is spotty in its distribution. It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.The mid and lower snowpack are well-settled and strong.

Problems

Storm Slabs

Forecast precipitation will come in as snow at upper elevations and rain at lower. Storm slabs will become more reactive as new snow amounts accumulate. Expect loose wet avalanches where the precipitation falls as rain or as a mix of rain and snow.

Watch for signs of instability such as whumpfing, or cracking. Extra caution needed around cornices with current conditions.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer buried 50 to 100 cm is still surprising people and producing large and destructive avalanches in the north of the region. Be particularly cautious around upper treeline and alpine terrain on shady aspects.

Be aware of the potential for wide propagation due to the presence of buried weak layers.Avoid steep terrain or areas with a thin or variable snowpack.Pay attention to overhead hazards like cornices, which could trigger persistent slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 14th, 2018 2:00PM