Avalanche Forecast

Issued: Nov 25th, 2014 9:11AM

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

jlammers, Avalanche Canada

South Rockies.

The avalanche danger is expected to increase as weather systems roll across the provinceadding to the developing storm slab. In deeper snowpack areas Wednesday's avalanche danger may be HIGH.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A low pressure system off the coast will move inland bringing significant precipitation across the south of the province on Wednesday and Thursday. Uncertainty lies in precipitation amounts and the timing of rising freezing levels; however, some models indicate freezing levels reaching 2000m by late Wednesday. On Friday a northwest flow will bring cooling, light flurries and a mix of sun and cloud.Wednesday: 10-20 cm of snow / Moderate to strong west winds / Freezing levels at about 1500mThursday: 10-20cm of snow / Strong southwest winds / Freezing levels at about 2000mFriday: Mix of sun and cloud with light flurries / Light northwest wind / Freezing level at surface

Avalanche Summary

No avalanche activity has been reported. This may speak more to a lack of observations rather than actual conditions. In the neighboring Lizard/Flathead region, natural and human-triggered avalanches to size 2 have failed on basal facets. I suspect a similar pattern of avalanche activity may be developing in some of the deeper snowpack areas within this region. With forecast weather, I expect continued storm slab activity with the potential to trigger deeper, more destructive weaknesses at the base of the snowpack.

Snowpack Summary

As we begin our forecasting season we are working with very limited field data. If you have been out in the mountains, please send us a note with your observations to forecaster@avalanche.ca.The limited field data that we have received suggests that there is not enough snow below treeline for avalanche activity. At higher elevations, the developing storm slab may be sitting on a weak layer of facetted snow, surface hoar, and/or a wind or sun crust that developed earlier in the month. This storm slab has been touchy to human triggers and has been reactive on basal facets in the Lizard/Flathead Region. I would expect similar conditions in some of the deeper snowpack areas within the South Rockies region.I expect avalanche activity to increase in size and frequency with forecast wind, snow and warming.

Problems

Storm Slabs

Avalanche Danger is expected to increase as a warm and punchy weather system rolls across the province. Pay attention to localized conditions as snowpack structure varies dramatically throughout the region.

Be alert to conditions that change with elevation.>The new snow will require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Nov 26th, 2014 2:00PM