Avalanche Forecast

Issued: Mar 18th, 2015 4:00PM

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

rupert wedgwood, Parks Canada

Jasper.

Solar radiation will rapidly and dramatically increase the avalanche danger on exposed slopes, with maximum effect latter in the day.

Summary

Weather Forecast

Cooling tonight with the freezing level rising to 1800m on Thursday and to 2100m on Friday. A westerly flow bringing snow flurries that may, by the weekend, provide another 20cm of snow in the alpine. Light wind will be south and westerly.

Snowpack Summary

Crusts exist up to 2200m on all aspects and extend higher on solar aspects. Above treeline wind slabs up to 65cm thick can be found in isolated locations. Bonding is generally good, however a graupel layer has recently been shown to shear with moderate force at the interface. Deeper weaknesses can be found near the base of the snowpack.

Avalanche Summary

No recent activity observed. A large cornice failure onto a easterly facing alpine start zone, known to be a frequent performer, failed to produce an avalanche. Limited older (>48hrs) size 2 activity from treeline and above is thought to have been triggered by solar radiation.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

Problems

Wind Slabs

Soft slab conditions on lee alpine aspects appear to have bonded well in most locations. At 2400m a graupel layer marks the interface and may be below 65cm of wind blown snow from last week. This sheared with moderate force during field tests (18th)

Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Deep Persistent Slabs

Large cornices or surface avalanches are the likely trigger.

Extra caution needed around cornices with current conditions.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 19th, 2015 4:00PM