Avalanche Forecast

Issued: Feb 9th, 2015 8:23AM

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

rbuhler, Avalanche Canada

South Columbia.

Lingering storm instabilities will persist for several days, especially in the alpine. Human-triggering remains likely and conservative decision-making remains critical.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure will build over the interior on Tuesday. Mostly cloudy conditions are expected but sunny breaks are possible. Light scattered flurries are expected in the morning but things should dry out by the afternoon. Alpine winds should remain light. Freezing levels on Tuesday are expected to be around 1600m but should fall to near valley bottom Tuesday overnight. On Wednesday, mainly dry conditions are expected with a mix of sun and cloud. Freezing levels are forecast to climb as high as 2000m by the end of Wednesday. Thursday might be the first day with a lot of sun and freezing levels are forecast to climb to around 2500m.

Avalanche Summary

Widespread natural, human-triggered, and explosive controlled avalanches up to size 3 were reported on Friday through Sunday. This includes both storm slabs and persistent slabs. Many avalanches started dry and ended wet, running to valley bottom. On Tuesday, natural avalanches remain possible at upper elevations but are generally not expected. Human-triggering remains likely and travel in avalanche terrain is not recommended until the storm slab has had a chance to stabilize.

Snowpack Summary

60-100cm of recent storm snow sits over the late-Jan weak layer at higher elevations. This snow is expected to be settling rapidly with the warmer temperatures. Rain has soaked the snow surface up to around 1900m and moist snow is reported to at least 2200m. Strong SW winds have formed wind slabs in exposed leeward terrain features. The storm slab sits on an old rain crust at lower elevations, variable surface hoar, and/or wind affected surfaces at higher elevations. The mid-January surface hoar is typically down 80-120cm and has been very reactive in some areas. The mid-December weak layer is down around 1.5m but has generally been unreactive.

Problems

Storm Slabs

Strong winds, heavy snowfall, and high freezing levels over the weekend created widespread storm slabs at higher elevations. These slabs are expected to remain reactive to human-triggering for several more days.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>The widespread storm slabs will require several days to settle and stabilize. Travel in avalanche terrain is not recommended.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Persistent Slabs

The mid-Jan buried persistent weak layer has become very reactive with recent storm loading and may remain sensitive for several more days. Smaller avalanches or cornice falls may step-down to this layer resulting in very large avalanches.

Be aware of thin areas that may propagate to deeper instabilities.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Loose Wet

Loose wet avalanches are possible from steep terrain features at lower elevations where the rain has soaked the snow surface. If the sun comes out, sluffing from steep sun exposed slopes is possible.

Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Feb 10th, 2015 2:00PM