Avalanche Forecast

Issued: Apr 7th, 2014 9:46AM

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

jfloyer, Avalanche Canada

Kootenay Boundary.

With no overnight refreeze anticipated on Monday night, warming issues are a bid deal right now.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Warm weather is expected to persist through Tuesday before a pulse of precipitation associated with the passage of a cold front is expected Tuesday night, followed by a drop in temperature. Tuesday: Warm. Sunshine expected in the morning, becoming cloudy in the afternoon. Freezing level as high as 2800 m. Winds starting light, becoming moderate SW. Tuesday night: 2-8 mm of rain/sleet/snow with strong SW winds. Wednesday: Lingering flurries in the morning, becoming dry and bright later. Freezing level around 1800 m. Light NW winds. Thursday: Dry. Cloudy with some sunny breaks. Freezing level around 2000 m. Light westerly winds.

Avalanche Summary

On Saturday and Sunday, explosives control resulted in a number of avalanches up to size 2.0 in the Nelson area running in recent storm snow. Some loose wet slides up to size 1.5 were reported from solar aspects.

Snowpack Summary

A recent storm slab of 15-40 cm in depth sits above a 2-5 cm melt-freeze crust that developed last week on all but shaded North aspects in the alpine. This crust has been reported to be very hard ("knife" resistance) in some parts of the region and there may be a layer of surface hoar between it and the new storm snow above. There is now about 75 cm of well compacted snow above the March 10th melt-freeze crust. In some areas the March 10th crust is helping to bridge over the deeply buried late January/early February persistent weak layer. The Jan/Feb deep persistent weak layer continues to be a concern for very large destructive avalanches. Releases on this layer may be more likely during periods of strong solar radiation and/or prolonged warm temperatures at alpine elevations.

Problems

Storm Slabs

High freezing levels and intense sunshine are likely to increase the sensitivity of recent storm slabs that occupy the top 15-40 cm of the snowpack.

Extra caution needed around cornices with current conditions.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

The deeply buried weak layer of crusts and facets continues to be a concern for hard-to-predict very large avalanches. Warm temperatures, strong solar, or heavy loading from new snow or cornice falls are likely triggers.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Loose Wet

Forecast high freezing levels and strong solar radiation may result in loose wet avalanches releasing from steep terrain on solar aspects.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Apr 8th, 2014 2:00PM