Avalanche Forecast

Issued: Mar 16th, 2019 4:13PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs, Cornices and Loose Wet.

jsmith, Avalanche Canada

Cariboos.

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; intense solar radiation will increase the likelihood of natural and human triggered avalanches.

Summary

Confidence

Moderate -

Weather Forecast

SATURDAY NIGHT: Mostly clear / Light, northwesterly winds / Alpine low -5 / Freezing level valley bottom.NOTE: Saturday night is the last night of the forecast period that freezing levels are expected to drop at night. This will significantly increase the impact of day time warming on the snowpack.SUNDAY: Sunny / Light, northwesterly winds / Alpine high 1 / Freezing level rising to 2200 m.MONDAY: Sunny / Light, northwesterly winds / Alpine high 4 / Freezing level rapidly rising to 2900 m.TUESDAY: Sunny / Light to moderate, southerly winds / Alpine high 6 / Freezing level 2900 m.

Avalanche Summary

On Friday, two naturally triggered, size 2-2.5, persistent slab avalanches were reported on solar aspects in the alpine. Another persistent slab, size 2 avalanche was remotely triggered by a skier from 5 m. away on a southeast aspect at 2300 m. in steep, rocky terrain. Human triggering of these persistent slabs is expected to increase with the forecast sunshine and warming.

Snowpack Summary

30-55 cm. of recent storm snow is sitting on a pile of facets (sugary snow), as well as a crust on sun exposed slopes. The recent storm snow has settled into a cohesive slab and is ripe for human triggering. This persistent slab is currently our primary concern.At lower elevations below treeline, a weak layer buried in mid-January can be found approximately 50-90 cm. deep. This layer consists of surface hoar and facets, and may be combined with a crust on south facing slopes. This layer has recently been unreactive, however, the forecast warming event may awaken this layer, resulting in large, destructive avalanches. Steep cutblocks and large open glades at lower elevations are the most likely places to trigger this layer.The lower snowpack is generally considered to be strong, except for shallow, rocky areas in the alpine.

Problems

Persistent Slabs

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; especially at treeline and above.

Use extra caution on solar aspects where the new snow is sitting on a crust.Avoid steep terrain where the snow feels moist or slabby.Avoid convex slopes on rocky terrain with a variable snow depth.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Cornices

Sunshine and rising freezing levels will elevate the potential for cornice failures resulting in large avalanches.

Avoid exposure to cornices and sun exposed slopes when the solar radiation is strong.Cornice failures have the potential to trigger large avalanches on deeply buried weak layers.Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Loose Wet

Pin-wheeling snow below cliffs is a common sign that loose wet avalanches are becoming more likely.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid steep, sun exposed slopes when the solar radiation is strong.Reduce exposure to over-head hazards such a large cornices during periods of strong solar radiation.

Aspects: East, South East, South, South West, West.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 1.5

Valid until: Mar 17th, 2019 2:00PM