Avalanche Forecast

Issued: Jan 28th, 2013 9:08AM

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

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Fair - Freezing levels are uncertain on Wednesday

Weather Forecast

Synopsis: Northwesterly flow will bring a series of low-intensity pulses of precipitation interspersed with short-lived periods of clear weather to the region through the forecast period. Temperatures will start out fairly cool but become mild on Wednesday.Tuesday: Mainly dry during the day. Temperatures around -10C. Northwesterly winds, gusting to 30km/h at ridgetop.Wednesday: Light snowfall, up to 5cm. Treeline temperatures rising to around -1C. Northwesterly winds gusting to 50km/h at ridgetop.Thursday: Dry and bright. Temperatures rising through the day with the possibility of above zero temperatures at treeline in the afternoon. Generally light northwesterly winds.

Avalanche Summary

Explosive avalanche control on Monday produced loose avalanches that ran on the upper surface hoar layer and deeper slab avalanches (up to 100 cm deep) that ran on basal facets on very steep north-facing alpine slopes. There have been no natural avalanches reported since the small cycle (up to size 1.5) on Thursday and Friday last week.

Snowpack Summary

Recent storm snow amounts over the past few days are 30 to 40 cm with as much as 60cm reported. Over the weekend, this low density storm snow started to settle into more of a cohesive slab, although little activity was reported through the weekend. Below the new snow is a suncrust on steep southerly facing slopes and a surface hoar layer at treeline and lower elevations (but it has a patchy distribution). Early January surface hoar is now around 60 - 80 cm deep and is reported to be patchy. It is most likely to be preserved on shady slopes below treeline.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent storm snow overlies surface hoar at treeline and below. Wind slabs are likely and will build on south and east facing slopes in response to reverse loading by NW winds.
Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Dig down to find and test weak layers before committing to a line on steep open slopes at treeline and below.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 29th, 2013 2:00PM