Avalanche Forecast

Issued: Mar 12th, 2014 9:59AM

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

ghelgeson, Avalanche Canada

Cariboos.

The current snowpack presents a serious challenge. Check out our latest blog for a look into the recent avalanche cycle and our best guess into what the future holds.

Summary

Confidence

Poor - Freezing levels are uncertain

Weather Forecast

Synopsis: A ridge of high pressure dominates the pattern for most of Thursday giving way to a pacific front Friday. Freezing levels are forecast to remain at spring like heights for the period (1300m - 2000m). Look for clearing skies Saturday. There is very little consistency from one model to the next at this time, thus my confidence in this forecast is quite poor.Thursday: Freezing Level: 1300m - 1600m; Precip: nil; Wind: Light, S | Mod W at ridgetop.Friday: Freezing Level: 800m - 1500m; Precip: 4/5mm - 4/8cm; Wind: Strong, SW | Extreme SW at ridgetop.Saturday: Freezing Level: 800m - 1700m; Precip: 1/4mm - Trace/5cm; Wind; Strong, SW | Extreme SW at ridgetop.

Avalanche Summary

No avalanche activity was reported on Tuesday.On Monday evidence of a natural avalanche cycle to size 3.5 was observed. The activity likely occurred on Sunday with many of the avalanches releasing on the February 10th interface. Large cornice fall was also reported in the region. A report also came in about a close call on Sunday. A ski touring party had 1 partial burial and a full burial by what sounds like a size 3.5 avalanche in the Ozalenka Valley south of McBride. The slab thickness was about 100cm and the avalanche covered about 8 hectares. Everybody walked/skied away from the incident.

Snowpack Summary

Up to 80cm of snow fell over the past week. This storm slab overlies small surface hoar crystals in sheltered areas and a sun crust on previously sun-exposed slopes. The storm snow may be strengthening somewhat, although it may continue to be reactive in wind exposed terrain or where it overlies the buried crust. Low elevation terrain and sun-exposed slopes are likely seeing a daily melt-freeze cycle. Cornice development has also been significant.There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies about a metre below the surface, and includes weak surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. Potential triggers at this point include a surface slab in motion, a large cornice fall, or intense solar warming.For the most part, the mid and lower snowpack are strong and well consolidated. Weak basal facets exist in some areas, but triggering is unlikely.

Problems

Storm Slabs

Storm slabs may become less likely to trigger in some areas, but solar warming may reactivate natural activity. Storm slabs may be particularly reactive in lee alpine terrain or on sun-exposed slopes where they likely overlie a buried crust.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid areas with overhead hazard.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

The early February weak layer may be less likely to trigger, but remote triggers continue in isolated terrain. Very large avalanches may result from a storm slab in motion, a cornice fall or intense solar radiation.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Cornices

Recent storms have formed large cornices which are likely unstable. Cornices may be destructive by themselves and could also become a trigger for an avalanche on the slope below.

Do not travel on slopes that are exposed to cornices overhead.>Cornices become weak with daytime heating. >Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Mar 13th, 2014 2:00PM