Avalanche Forecast

Issued: Mar 19th, 2018 9:00AM

The alpine rating is low, the treeline rating is low, and the below treeline rating is low. Known problems include Storm Slabs, Loose Wet and Cornices.

VIAC Bill Phipps, VIAC

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Vancouver Island.

Summary

Confidence

Moderate - Weather models in agreement but few field observations

Travel & Terrain Advice

The possibility of loose wet avalanches will still exist on solar aspects Monday and Tuesday so avoid exposure above and in terrain traps, as even small wet avalanches have significant force. The next storm will slowly build into Wednesday with a good amount of new snow and moderate winds. Take the time to study the bond of this new snow to the crusts that have formed over the past few days. Avoid areas that will be loaded by the SE winds until time allows this new snow to bond. Expect avalanche activity on all slopes/aspects in the alpine and open treeline especially N-W and crossloaded features.

Avalanche Summary

No new avalanches have been reported during the past forecast period. A few very small loose wet sloughs have been seen as trees and rocky outcrops have warmed during the day and pealed off their winter coats.

Snowpack Summary

Spring has arrived and so has the cycle of the sun. Cool nights have created crusts of varying support on all aspects and elevations (except maybe a few alpine pockets that lurk dark in the shadows) and daytime warm temps and sun result in slushy fun turns especially on solar aspects at treeline and below. A very typical spring snowpack….

Snowpack Details

Surface:

Melt freeze crusts warming to moist/wet snow on solar aspects during the day. Upper: Well settled. Mid: Well settled. Lower: Well settled.

Past Weather

A trace of new snow fell in the east and west, while northern regions saw up to 5 cm of new. Winds have been from variable directions, calm to light. Temperatures have been fluctuating from around -3 at night to +4 to +7 in the warmth of the day. Rumors of t-shirts and shorts have circulated from local ski resorts (no bikinis yet though).

Weather Forecast

Back to winter as a moderate low pressure system brings unsettled weather and a half decent load of new snowfall near the end of the forecast period. Monday: no new to a trace of possible mixed precipitation (type of precip is elevation dependent), winds variable and light, temps 0 to -3, freezing level 800 to 1400 m. Tuesday: 0-5 cm of mixed precip (type elevation depended), winds mainly light SW, temps -1 to -4, freezing level 900 to 1200 m. Wednesday: 10-20 cm of new snow, winds moderate SE, temps -2 to -5. freezing level 800 to 1000 m.

Problems

Storm Slabs

An icon showing Storm Slabs
Wednesdays storm will drop moderate amounts of new snowfall during the day with more expected overnight into Thursday. Except the bond of this snow to the spring crusts that have formed to be in question. This new snow may possibly produce natural avalanches and will very likely see avalanches triggered with human activity up to size 2. The potential avalanche cycle will exist in the alpine and open treeline on all aspects, especially N-W with the moderate gusting to strong winds forecast, resulting in wind transport and additional loading.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 2

Loose Wet

An icon showing Loose Wet
Although Mondays and Tuesdays temps are dropping, the potential of loose wet avalanches still exists. These dangers will exist on solar aspects in treeline and below and will mainly be associated with tree bombs and cliff faces. Triggering is likely with natural (sun) and very likely with human activity up to size 1. Though small, when in the proximity of terrain traps these sloughs can pose a danger to us.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 1

Cornices

An icon showing Cornices
Warm temperatures have begun to weaken the cornices that exist in the alpine and treeline along our ridges and summits. Avoid exposure above and below these threats especially during warm daytime periods. These cornices may possibly trigger naturally and with human activity, are mainly found on N-W aspects and will be most fragile in the heat of the day Monday and Tuesday up to size 2.

Aspects: North, North East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1

Valid until: Mar 21st, 2018 9:00AM

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