Avalanche Forecast

Issued: Jan 29th, 2013 9:19AM

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

jfloyer, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: Continued northwesterly flow will bring light pulses of precipitation to the region interspersed with some dry patches.Tuesday night: 2-5 cm new snow.Wednesday: light snow through the day, another 2-5 cm. Treeline temperatures should peak around -2C. Northwesterly winds gusting to 40 km/h.Thursday: Flurries. Freezing level rising to around 1400 m. Light northwesterly winds.Friday: Dry. Temperatures around -6C at treeline. Light northwesterly winds.

Avalanche Summary

On Monday, there were a few, mostly loose snow avalanches on north-facing slopes at higher elevations. There was one small (size 1) human-triggered avalanche reported from 1500 m near valley bottom near a creek. I suspect this is the kind of place surface hoar (most likely the Jan 24th layer, buried 40 cm) would be well preserved. Another small human-triggered avalanche was reported from a north-facing slope in the alpine.

Snowpack Summary

Approximately 30 to 50 cm of recent storm snow overlies a weak layer comprising of surface hoar in shady locations, facets at higher elevations and a sun crust on solar aspects. The recent new snow sitting above this interface has been slowly consolidating from fresh powder into a more cohesive slab. A mid-pack surface hoar layer buried in early January is down around 90 cm, and is best preserved below approximately 1700 m. A freezing rain crust has been reported near the surface (it may now be buried by light snow) in the Monashees, particularly in areas close to Mabel Lake.

Problems

Storm Slabs

Watch for storm snow settling into a more cohesive slab on steep southerly slopes where it covers a crust or shady sheltered slopes in open glades where it rests on surface hoar. NW winds will develop fresh wind slab on S and E facing slopes.

Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Watch open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Use ridges or ribs to avoid pockets of wind loaded snow.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Jan 30th, 2013 2:00PM