Saturday January 23, 2021

Monday January 25, 2021
Sunday January 24, 2021
Saturday January 23, 2021
Confidence: Moderate - Confidence is Moderate however timing and volume of forecasted precipitation vary. The bulletin has been edited as of Sunday Jan 24 at 0500am based on increased precipitation amounts.

Main Concerns

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

Travel & Terrain Advice

Beginning Sunday January 24th, dangerous avalanche conditions will exist. Cautious route-finding and conservative decision-making will be essential Sunday into Monday. The avalanche hazard will increase with incoming precipitation amounts and strong winds. Be aware as the storm arrives to your area and be on the lookout for signs of instability such as snow cracking underfoot/under your sled. As precipitation volumes and winds increase in your area, the possibility of triggering an avalanche will become a “very likely” scenario.

Be aware of changing snow/avalanche conditions on Sunday and into Monday.

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.

If forecasted precipitation and wind speeds hold true, the seasoned backcountry veteran will seek out “Simple Avalanche Terrain” where the slope angle is generally under 30 degrees.

Avalanche Summary

It’s been boiler plate hard pack out there, no new avalanches to report. Expect this to change sharply with the arrival of new snow and strong winds on Sunday January 24th.

Avalanche Problems

Persistent Slab

There exists 2 (persistent weak layer = PWL) within the upper snowpack which will be further compromised by the arrival of new snow in the form of precipitation and wind loading.

The positive point of this Persistent slab problem is that it is a very shallow problem (at least on Saturday). On Sunday into Monday with the arrival of additional precipitation and strong winds, the two PWL’s contained within the upper snowpack will become more avalanche prone.

Location: Found at all elevation bands and on multiple aspects

Possibility: Triggering of this avalanche problem is “possible” to “likely” from light loads such as skiers, snowshoers and snowmobilers. Natural avalanches are unlikely.

Size: If triggered expect these avalanches to be large enough to bury a person (size 2).

Wind Slab

Beginning Sunday, wind slabs could be initiated on all aspects (due to strong winds shifting from different aspects), this avalanche problem overlies a variety of surfaces including a thick ice crust as well as a surface hoar layer within the upper snowpack. Expect that this problem will reveal itself Sunday mid-day as new snow and excessive wind speeds begin to transport and overload down wind areas creating prime zones for human triggering Sunday afternoon and into Monday.

Location: All aspects in down wind areas at all elevation bands Sunday into Monday.

Possibility: Triggering of this avalanche problem is “likely to very likely” from light loads such as skiers, snowshoers and snowmobilers. Natural avalanches are “possible” to “likely” depending on elevation band.

Size: If triggered expect these avalanches to be large enough to bury a person, size 2.

Storm Slab

On the south island, where winds are forecasted to arrive without enough “punch” to redistribute snow, there is a possibility that storm slabs could exist on all aspects and elevations.

Location: All aspects and at all elevation bands Sunday into Monday.

Possibility: Triggering of this avalanche problem is “possible” from light loads such as skiers, snowshoers and snowmobilers. Natural avalanches are “possible” to “unlikely” depending on elevation band.

Size: If triggered expect these avalanches to be large enough to bury a person, size 2.

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.

Snowpack Details

SurfaceWidespread surface hoar (PWL)
Upper5-10 cm below the surface exists a reactive facet layer sitting on top of a firm melt freeze crust (as of Friday Jan 22)
Midgenerally well settled with several melt freeze crust layers
Lowerwell settled and well bridged and includes a 10cm thick layer of large facets

Past Weather

Cool, clear and calm weather has contributed to a stiffening of the snowpack however it has also allowed for the growth of surface hoar at the snowpack surface.

Weather Forecast

There is a discrepancy in terms of extent of precipitation and wind for Vancouver Island on Sunday. The southernmost reach of the avalanche forecast region shows Moderate winds throughout the Storm event on Sunday with 15cm of snowfall. The northern reach of the forecast region shows Strong to Extreme wind gusts during the storm and precipitation amounts ranging from 15cm snow to 30cm snow :). All regions agree on a Below Treeline Freezing level which is positive however, the Southern region may have slightly safer avalanche conditions this Sunday into Monday based primarily on the less aggressive wind speeds forecasted for the South island.

Saturday: No precipitation expected, Winds Light from the NW, Freezing level will reach a high of 600 meters south island and 1,100M on the North Island.

Sunday: Moderate to strong precipitation expected (regionally dependant between 15cm to 30cm Snow), Winds Strong from the South in morning shifting to Strong North winds at mid-day, Freezing level will reach a high of 750 meters.

Monday: Very light precipitation expected (less than 1 cm Snow), Winds Strong from the North shifting to Moderate North winds in afternoon, Freezing level 650M elevation

Posted on Saturday January 23, 2021 by Ryan Shelly

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