Avalanche Forecast

Issued: Apr 5th, 2016 8:29AM

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

pmarshall, Avalanche Canada

Cariboos.

Wednesday is your best bet if you're craving fresh snow, but watch for fresh touchy wind slabs in exposed lee terrain.

Summary

Confidence

Moderate

Weather Forecast

WEDNESDAY: Periods of snow 15-25 cm. The freezing hovers between 1500 and 1800 m. Winds are moderate to strong from the W-NW. THURSDAY: Mainly sunny. The freezing level shoots up to 3200 m. Winds should ease to light and variable. FRIDAY: Mainly sunny. The freezing level stays above 3000 m and winds should remain light.

Avalanche Summary

Cooler temperatures and cloud cover helped reduce avalanche activity on Monday (or perhaps lousy weather and conditions kept observers out of the mountains). I suspect isolated wind slabs and fresh loose wet slides were the main concerns on Tuesday and Wednesday. As we move back to warm and sunny weather I would expect renewed loose wet activity on solar aspects, natural cornice falls, and isolated large persistent and wet slab avalanches.

Snowpack Summary

10-15 cm of new snow fell on Monday (with another 20 cm possible on Tuesday), combined with cooling temperatures and moderate or strong W-NW winds. Fresh wind slabs are likely in exposed lee and cross-loaded terrain. A new melt-freeze crust may have formed below the fresh snow, which should help temporarily stabilize the snowpack. The March 22nd rain crust is buried 50-60 cm deep up to around 2000 m. We could see more activity on this layer when temperatures soar later in the week. The late February persistent weak layer is now down 60 to 120 cm below the surface. While it may be a concern in isolated terrain, it would probably take a large trigger like a cornice fall or surface avalanche in motion to provoke it.

Problems

Wind Slabs

New snow and strong westerly winds have combined to build fresh wind slabs in exposed leeward terrain. Expect any new snow to sluff off easily if the sun pokes out in the afternoon.

Be alert to conditions that change with elevation.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Cornices are large and weak and could pop off naturally as temperatures rise and the sunshine returns.

Do your best to avoid traveling on or underneath cornices. If you have to, move quickly and only expose one person at a time.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

The chance of slabs failing on buried persistent weaknesses will be on the rise this week. Extra caution is necessary if the snow becomes wet and slushy.

A buried persistent weak layer (PWL) is lurking in our snowpack which means there is potential for large destructive avalanches that have the capability to run full path.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 6th, 2016 2:00PM