Avalanche Forecast

Issued: Mar 3rd, 2021 1:00AM

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

Bill Phipps, VIAC

Vancouver Island.

No new big avalanche activity reported over the past two days. Some minor loose wet activity up to size 1 on solar asp at treeline and all asp below treeline. Tree bombs and pinwheeling. Update for last weekends avalanche activity in the Cain region. One very large isolated avalanche size 2.5 to 3 was noted off the side of Table mountain, just above the Table Hapush col. A couple size 2 and a few size 1 for Cain's west bowl were reported as either human or naturally triggered but the triggers were not confirmed. The estimated timing of these events was either Friday or Saturday.

Summary

Past Weather

Small amounts of new snow fell and were warmed by mild temperatures. Winds were light to moderate from variable directions.

Weather Forecast

New snow! Starting with moderate and climbing to heavy snowfall is the forecast for the next three days. Temps will be cool and strong rising to extreme SE winds will accompany the storm cycle. Wednesday: 1 to 15 cm of new snow with greater amounts for Strathcona Park, the north and the west regions (least for the eastern side of the island). Winds strong to moderate SE. Temps for 1500 m -5 to -1. Freezing levels 550 to 950 m.Thursday: 6 to 20 cm of new snow. Winds strong to extreme SE. Temps for 1500 m -1 to -4. Freezing levels 500 to 1100 m. Friday: 16 to 34 cm of new snow. Winds ranging from light to strong S through E. Temps for 1500 m -4 to -1. Freezing levels 600 to 1100 m. Estimated snowfall totals by the end of the day FridayMyra region 63 cmMt Washington zone 36 cmMt Cain 35 cmArrowsmith 24 cm5040 68 cm

Terrain Advice

Snow fall amounts are forecast to climb significantly over the next three days. Carefully analyses how much snow is above the old crust, to estimate the potential size of avalanche one can expect. Avoid wind loaded aspects (ie N-W slopes) Thursday and Friday as strong to extreme winds will transport significant amounts of snow to these lee slopes, especially just down from ridge tops and on the lee sides of cross loaded features. Bowls and gullies will load up with wind transported snow and magnify the potential size/depth of an avalanche. Give cornices a with berth as they continue to grow along treeline and alpine ridges. Avoid travel above or below these features.

Snowpack Summary

Well unfortunately we did not get the moderate snowfall that was forecast over the past three days. Only 2 to 10 cm of new snow fell on our crust in the island hills. This new snow is moist on all aspects from approx 1400 m and below. On solar aspects the moist snow can be found even higher. High non solars escaped the warm up and some nice preserved cold snow can be found.

Snowpack Details

Surface: Mainly moist new snow bonding moderate to the old crust, some winds slabs still linger in the alpine.
Upper: A crust with variable support to skis and unsupportive to sleds and foot traffic. Some dry loose snow under.
Mid: Well settled with some old crusts
Lower: Well settled

Confidence

High - Good amounts of field data and weather models in agreement. A crust overlies a very well settled snowpack so we will mainly be dealing with new snow instabilities.

Problems

Cornices

Our cornices will continue to grow again this forecast period. Significant new snow and wind will add to the potential to trigger these beasts and the size of avalanche they may produce. Location: The N to W aspects of ridges in the alpine and treeline. Likelihood of triggering: Possible. Size: 1-3

Likelihood

Possible

Expected Size

1 - 1

Wind Slabs

New snow will certainly be transported and form touchy to reactive wind slabs over the next three days (esp as the SE winds climb to extreme Thursday night) Location: N through W aspects in the alpine and treeline elevation bands. Likelihood of triggering: Very likely with human travel and likely with natural triggers. Size: 1 to 3

Likelihood

Possible

Expected Size

1 - 1

Storm Slabs

Significant snow will fall on a old crust over the next three days creating potentially reactive storm slab avalanches. Location: All aspects and elevations (especially at treeline and alpine elevations) Likelihood of trigging: Likely with human activity and possible with natural triggering Size 1-2.5

Likelihood

Possible

Expected Size

1 - 1

Valid until: Mar 4th, 2021 1:00AM