Avalanche Canada mconlan, Avalanche Canada

South Rockies Avalanche Forecast

Mar 13th, 2018 4:33PM

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

Mild temperatures are expected in the morning followed by a cooling trend over the day. The best riding will be in areas sheltered from the warming and wind effects.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

WEDNESDAY: Morning sun and afternoon clouds with light snowfall at higher elevations and rain below, accumulation 1 to 2 mm, moderate southwesterly winds, alpine temperature 2 C, freezing level 3000 m dropping to 1500 m over the afternoon.THURSDAY:  Cloudy with light snowfall, accumulation 3 to 8 cm, light westerly winds, alpine temperature -4 C, freezing level 1500 m.FRIDAY:  Cloudy with light snowfall, accumulation 5 cm, light easterly winds, alpine temperature -4 C, freezing level 1500 m.

Avalanche Summary

Widespread loose wet avalanches were noted on solar aspects to size 2 on Monday.  Explosive control in the Elk Valley triggered cornices on predominantly north aspects.  Evidence of natural slab avalanche activity was also observed on easterly aspects.  The slab depths were around 50 to 80 cm deep.

Snowpack Summary

Warm air temperatures and daytime sun have produced moist snow on all aspects.  With dropping freezing levels, the moist snow will harden into a melt-freeze crust.  On shady aspects at high elevations, lingering wind slabs in lee features and loose dry in sheltered features may still exist.A weak layer of surface hoar buried mid-February exists in parts of the region around 50 to 80 cm deep.  The lower snowpack is weak with a combination of crusts and facets near the bottom of the snowpack that are widespread.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5
Deeply buried weak layers linger in the snowpack. These layers are most likely to be triggered from thin snowpack areas. Avoid lingering below corniced ridges, as a cornice fall could trigger deeper layers.
Steep, south facing slopes are the most likely areas to trigger deeper layers.Avoid steep, rocky, and shallow snowpack areas where triggering deeper layers is more likely.Pay attention to overhead hazards like cornices which could trigger deep persistent slabs.

Aspects:

All aspects.

Elevations:

All elevations.

Loose Wet

An icon showing Loose Wet

Likelihood

Possible

Expected Size

1 - 2
High freezing levels, morning sun, and possible afternoon rain will warm the snowpack on all aspects. Pay close attention to the moisture of the snow surface and avoid overhead exposure. This problem will be reduced when the snow surface is frozen.
Avoid terrain traps such as gullies and cliffs where small avalanches can have high consequence.Watch for signs that the snow is moistening such as pin-wheeling and point-releases below cliffs.

Aspects:

North, North East, East, South East, South.

Elevations:

All elevations.

Valid until: Mar 14th, 2018 2:00PM