Thursday January 21, 2021

Saturday January 23, 2021
Friday January 22, 2021
Thursday January 21, 2021
Confidence: High - High confidence - based on high quality information and consistent weather over the past week has helped to render a solid judgement. Could benefit from additional Alpine elevation band snowpack observations.

Main Concerns

Persistent Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Use small slopes to test and investigate snowpack stability prior to stepping out into large slopes.

Careful and cautious route finding when transitioning from scoured areas into areas of wind loaded snow. Avoid traveling below and above cornice features as they are large and generally unstable.

Currently we are experiencing generally safe avalanche conditions, particularly at the Below Treeline and Treeline Elevation bands however watch for unstable snow on isolated and extreme terrain features.

Avalanche Summary

No New avalanches reported this past week. Multiple sets of trip reports from recreational and professional personnel indicate some reactivity in the upper snowpack however these results also indicate a “stubborn” degree of sensitivity and are requiring major input (large trigger) in order to initiate these upper snowpack layers.

Please keep the observations coming! Thank you to those who took the time to post a MIN report or submit obs via our email forecaster@islandavalanchebulletin.com or via social media. It is much appreciated! Thank you Ben Godwin, SportNewK and Skafti and Theron Finley, Graeme and Joe for your reports.

Avalanche Problems

Persistent Slab

There exists a reactive layer (persistent weak layer = PWL) comprised of decomposing new snow of anywhere between 5-10cm sitting on a layer of facets (dry sugary snow crystals a.k.a. PWL) this issue can be found specifically on Northerly aspects and can be initiated by ski cuts on extreme terrain.

The positive point of this Persistent slab problem is that it is a very shallow problem, currently it exists on Northerly (sun protected) aspects at higher elevation but will certainly be re-visited Sunday into Monday as additional precipitation and strong winds arrive to redistribute and possibly load up this layer in specific areas. There remains a possibility for initiating small avalanches (size 1) in extreme and isolated terrain, particularly at the Alpine Elevation band.

Location: Found in Alpine and at upper Tree line elevation band specific to terrain just below ridge top and in down wind areas on steep unsupported (convex) terrain features on Northerly facing aspects.

Possibility: Triggering of this avalanche problem is unlikely from light loads such as skiers and snowmobilers. Natural avalanches are unlikely.

Size: If triggered expect these avalanches to be small, size 1.

As a reward for reading the whole paragraph - The best skiing can be found on WNW aspects at treeline and above, for reverse loading early this past week has left some decent powder snow conditions which are not deep but they are enjoyable turns nonetheless!

Snowpack Summary

A series of fluctuating air temperatures have created an array of upper snowpack melt freeze and rain crusts all within the upper 40-50cm of the snowpack. Within 5-10 cm of the upper surface, a relatively supportive crust exists and at the Below Treeline elevation band this crust is exceptionally dense and firm and provides challenging ski/snowmobile conditions until it softens (particularly at lower elevations (BTL)) with day time heating. Expect this crust to remain in place and firm/supportive as a result of generally cool air temperatures over the next several days.

Snowpack Details

Surface5cm of soft decomposing new snow overlying a firm melt/freeze rain crust with some faceting (PWL) growing on this melt freeze crust
UpperA series of rain and/or melt freeze crusts within the upper 50cm of the snowpack with new decomposing snow laminated between these crusts
MidWell settled and it includes a dormant PWL (currently listed as unreactive) mostly due to bridging of 1.2M to 1.5M well settled snowpack above the PWL
LowerWell settled and dense.

Past Weather

Generally cool Temps (air temperature below zero) and a stagnant weather pattern (moderate winds and very little loose snow available for transport) as of late have contributed to an increasing trend in snowpack stability on Vancouver island.

Weather Forecast

Thursday: Very light precipitation expected (1cm Snow) , Winds Light from the North, Freezing level will reach a high of 850 meters.

Friday: No precipitation expected, Winds Light from the North, Freezing level will reach a high of 700 meters.

Saturday: No precipitation expected, Winds Light from the WSW, Freezing level 800M elevation

Posted on Wednesday January 20, 2021 by Ryan Shelly

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