Friday April 16, 2021

Friday April 16, 2021
Saturday April 17, 2021
Sunday April 18, 2021
Confidence: Moderate - Avalanche danger ratings reflect the highest danger level expected over the course of the day (mid-day during peak of day-time heating). Weather forecast models are very well aligned and provide support to the forecasted avalanche problems.

Main Concerns

Cornice Fall, Loose Wet - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Please respect the current closures at Mount Washington, no access is permitted at anytime on the ski areas slopes or terrain.

During periods of intense warming and sunshine, avoid solar facing terrain.

Avoid travelling both above and below cornices.

Early starts may help to ensure you can accomplish your trip objective prior to arrival of day time high’s when the snowpack will become increasingly more unstable.

Major concern remains with the fact that no below freezing temperatures are taking place on Vancouver Island’s mountain ranges overnight. Expect continued destabilization within the layers that exist within the upper snowpack.

Possibility of isothermal snow may make for extremely challenging and dangerous travel as snow may readily collapse under an individual’s weight.

Avalanche Summary

No new avalanches reported.

Avalanche Problems

Cornice Fall

Expect Cornices to remain highly unstable as they continue to collapse and fall with major (above zero degrees ) air temperatures. The probability of natural cornice failures occurring during the day are near certain.

Location: Predominantly north aspects at ridge top in the Alpine and Tree line.

Possibility: Triggering of this avalanche problem is likely to very likely from light loads such as skiers. Natural avalanches are very likely.

Size: If triggered expect these avalanches to be large size 2, on isolated terrain features very large, size 3

Loose Wet

The loose wet avalanche problem will remain an issue as overnight temperatures will remain above zero degrees up to mountain top, expect south facing terrain to become rapidly unconsolidated earlier in the day as temps rise and the sun begins to directly radiate onto solar surfaces.

Location: South Aspects at all elevations

Possibility: Triggering of this avalanche problem is very likely from light loads such as skiers. Natural avalanches are very likely.

Size: Expect widespread size 1 to 2 avalanches

Snowpack Summary

Double digit air temperatures, coupled with strong sun and limited winds are reducing the overall mountain snowpack volume on Vancouver Island. The weather pattern will continue throughout the weekend further reducing snowpack volume as lower elevation band snowpack will become isothermal.

Snowpack Details

SurfaceWet melting snow surface and isothermal snow at Below Treeline elevation band
UpperWet snowpack possibly destabilized layers as a result of melt water percolating and exacerbating interface instabilities
MidWet snowpack possibly destabilized layers as a result of melt water percolating and exacerbating interface instabilities
LowerWell settled and dense.

Past Weather

This week has exhibited a major warming trend for the first time to Vancouver Island’s mountain ranges. Clear, sunny weather and light winds will continue to deteriorate stability and overall snowpack volume.

Weather Forecast

Double digit air temperatures near mountain top will persist this weekend.

Friday: No new precipitation, Winds light from the South will transition to Light Northerly winds late in afternoon, Freezing level rising during the daytime to 2,900 meters (which represents the traditional “summer time” freezing level) Temps at 1500 meters up to +11 degrees.

Saturday: No new precipitation, Winds light from the South will transition to Light Northerly winds late in afternoon, Freezing level rising to 3,000 meters. Temps at 1500 meters up to + 12 degrees.

Sunday: No new precipitation, Winds light from the North, Freezing levels dropping to 2700 meters (due to cooling from Northerly winds). Temps at 1500 meters +10 degrees.

Posted on Thursday April 15, 2021 by Ryan Shelly

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