Avalanche Forecast

Issued: Mar 12th, 2014 9:42AM

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

bcorrigan, Avalanche Canada

South Rockies.

Rain soaked and moist upper elevation snow packs may take a while to cool off and stabilize. Pay close attention to daytime heating and mature cornices. For more information on the tricky conditions see the latest:Forecasters Blog:

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: The ridge of high pressure holds for the next few days with clear skies and warm spring-like conditions. There is a possibility of moisture by the weekend.Tonight: Clear periods, freezing level will drop to valley bottom. ridge top winds light, occasionally gusting to strong from the west.Thursday: Sunny with cloudy periods, freezing level around 1400m. Light ridge top winds occasionally gusting to moderate.Friday: Cloudy with sunny periods, light to locally moderate precipitation amounts, freezing level around 1400 metres, winds from the southwest , light to moderate, occasionally gusting to strong.Saturday: Cloudy with scattered flurries. freezing level around 1400 metres, ridge top winds light, occasionally gusting to strong.

Avalanche Summary

No reports of avalanches in the forecast region from yesterday, but a neighboring region had a large, wet avalanche that ran full path between 2100m and 1700m. on a west aspect.. Cornices have gotten large and mature and may trigger large destructive avalanches if they fail. There have been two reports recently where human triggered avalanches were initiated from roads below clear-cuts and ran full path with destructive consequences. Daytime heating and nighttime cooling are a critical part of the daily hazard evaluation. Cut blocks, road cuts, and low angle terrain should be considered as possible start zones for avalanches during this warm period..

Snowpack Summary

Night time cooling will help to stabilize the tricky conditions as the storm slab settles and gains strength, although freezing levels are forecast to be up into the 1400 to 1600m range. Below that elevation there will be no overnight freeze and recovery of the snow pack. In some parts of the region, the snowpack is isothermal and saturated with water below 1600 metres. Any disturbance could trigger a wet dense avalanche on this type of snow. Above 1600m the previously mentioned weak layers still exist, especially on north aspects. Slopes gaining heat from the generally rising temperatures and strong spring sun should be highly suspect,.. and treated with respect and caution. The weak layers buried in this years snow pack are not going away soon, and may not go away until the seasons snow has completely melted, especially on north aspects

Problems

Storm Slabs

Rising freezing levels and solar input are major concerns right now. Wet surface snow avalanches may create a big enough load to trigger the weak layers buried deep in the snow pack. North slopes still have touchy storm slabs over weak layers

The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>Caution required around loaded road banks, cutblocks and other non obvious avalanche terrain>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Wet Slabs

Wet slabs are a concern on slopes with rain soaked snow now sitting over weak layers. Wet loose avalanches are also expected where rain soaked snow has lost its cohesion. Warm temperatures and solar radiation will contribute to the hazard.

Avoid steep unsupported terrain below treeline especially if the snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

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