Wednesday March 24, 2021

Friday March 26, 2021
Thursday March 25, 2021
Wednesday March 24, 2021
Confidence: Moderate -

Main Concerns

Cornice Fall, Wind Slab, Storm Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Practice patience and allow time for new storm instabilities to stabilize prior to committing to any steep terrain.

Plan routes and choose terrain that is low angle and supportive as you begin to venture into unmodified and uncontrolled snowpack and terrain.

Identify and avoid travel either above or below cornice features.

Adjust travel plans to ensure avoidance of slopes during warming and where rain events may occur.

Avalanche Summary

No new avalanches reported.

Confidence details: Limited recent public observations submitted to island forecasters. Thanks to those of you who have submitted observations. The freezing level tonight (Tuesday night) into tomorrow morning will dictate the stability trend and riding conditions for the next several days.

Avalanche Problems

Cornice Fall

Very large cornices exist and continued snowfall, wind and high humidity continue to promote cornice growth. Cornice failures have the potential to over load the snowpack and trigger both new snow instabilities as well deeper instabilities. Expect the new growth to be fragile and when temperatures and freezing levels rise become suspected triggers in bigger avalanche events.

Location: Many 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/snowmobilers. Natural avalanches are possible to likely.

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

Wind Slab

Wind slabs could become a factor Wednesday in areas where precipitation arrives in excess of 20cm coupled with strong winds and a lower freezing level. Found predominantly on downwind aspects, the predictability of the location of the wind slab will be difficult as winds shift overnight Tuesday during the storm from SW to NW. This avalanche problem overlies a variety of snow surfaces, mostly a wet upper snowpack surface or a firm melt freeze crust (depending on elevation and aspect).

Location: Many aspects and found in both the Alpine and Tree line. Winds are shifting direction on Tuesday night into Wednesday which will contribute to reverse loading and essentially complicate terrain management due to availability of new light dry snow being relocated to many downwind aspects.

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

Size: If triggered expect these avalanches to be size 1, on isolated terrain features very large, size 2 .

Storm Slab

This new avalanche problem will develop in areas that receive snow in excess of 20cm- sensitivity to triggering will increase over the course of the storm event. On isolated Alpine terrain expect this new snow to overly a firm upper snowpack, on solar aspects, expect the storm snow to overlie a melt freeze crust.

Location: All aspects, Alpine and Tree line. Below tree line hazard is from above.

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

Size: If triggered expect these avalanches to be large size 1, on isolated terrain features large, size 2.

Snowpack Summary

Storm snow over the weekend has settled and consolidated at higher elevations. At the Treeline and Below Treeline elevation band, a melt freeze cycle has begun to take shape and has also consolidated the upper snowpack into a well bonded/bridged snowpack.

Snowpack Details

SurfaceOn Wednesday, a storm cycle will deposit snow/possibly rain onto the surface as the freezing level teeters on the verge of being a powder day or a wet storm snow day
UpperWell bonded and dense moisture laden snowpack
Midwell settled due to melt freeze cycle snowpack has undergone
Lowerwell settled and dense

Past Weather

A series of warm days have moved the snowpack back into a spring melt - freeze cycle. This may end tomorrow with the arrival of additional precipitation and sustained NW winds for a 72 hr period.

Weather Forecast

Wednesday: 10cm Snow throughout forecast region and (up to 20cm for North and West ends of forecast region). The freezing level may rise (1500+M) overnight on Tuesday night during the peak of the storm. As a result, we may see Rain/heavy wet snow for the Treeline elevation band and below Treeline Elevation band. Strong SW winds will shift overnight to Moderate NW winds in the morning. The Freezing level will begin to cool early Wednesday morning with the onset of the NW winds, (Freezing Level during day 1200M approx) by morning.

Thursday: Less than 1cm snow throughout forecast area, Winds Moderate from the NW (gusting to Strong), Freezing level 1,000M

Friday: No snow expected throughout forecast area, Winds Moderate from the NW, Freezing level 1300M.

Posted on Wednesday March 24, 2021 by Ryan Shelly

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