Avalanche Forecast

Issued: Mar 8th, 2014 9:15AM

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

tim haggarty, Parks Canada

Waterton Lakes.

An avalanche cycle is occurring. Heating in the form of sun on Saturday and Rain on Sunday may cause additional large and destructive avalanches. Travel is not recommended.

Summary

Weather Forecast

Warm temperatures are the main concern for the next few days. Some solar heating should be expected Saturday with freezing levels near 1800m. A warm wet system will reach the area in the evening. Up to 30mm of Precip is expected with freezing levels around 2000m. These heat inputs will affect surface snow and weaken both slabs and cornices.

Snowpack Summary

Warm conditions persist and maintain moist snow below 1800m. Suncrusts have formed on solar aspects. Storms slabs up to 50 cm thick have formed with W winds and warm temps. 70 to 170cm now buries the weak February facet layer and large avalanches have resulted when this layer is triggered demonstrating the ability of these slabs to propagate.

Avalanche Summary

Wind and warm temps caused a cornice failure that triggered a deep slab in the Alpine that ran to valley bottom. Moist snow at low elevations failed as slabs both on storm interfaces and the persistent layer with avalanches running near the bottom of their run outs. Loose wet events have occurred with warm temps BTL and on solar aspects.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

Recent storms with warm temps and West winds have created slabs and built cornices. Wet slabs are failing BTL and solar aspects, cornices and windslabs are failing at TL and above.

Pay attention to overhead hazards like cornices.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

The weak February facet layer is now buried up to 170cm deep. Large loads such as cornices have triggered this layer where it is deep and it has failed with sluffing and heating where it is shallow. Long propagations are possible with this layer.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Solar heating will likely result in these events occurring to ridge tops Saturday. Warm temps as well as the rain expected Sunday will cause these events at low elevations. Be aware that these small events may act as the trigger for deeper slabs

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Mar 11th, 2014 5:00PM