Purcells

The full day of sun following cold stormy conditions is expected to destabilize the recent storm snow. Loose wet sluffing, cornice failures, and solar triggered slab avalanches are all expected. Use extra caution during the heat of the afternoon.

Fair - Timing or intensity of solar radiation is uncertain

A ridge of high pressure should keep the region mainly dry until Friday night. On Wednesday, mostly sunny conditions are expected with light-moderate alpine winds from the W to NW. Freezing levels are expected to be around 1000m in the morning and 1700m in the afternoon. On Thursday, mostly sunny conditions are expected with light-moderate alpine winds from the SW to NW.  Freezing levels are forecast to be around 1500m in the morning and climb over 2000m in the afternoon. Friday looks be similar with mainly sunny conditions, light alpine winds, and freezing levels reaching around 2500m. A weak storm system is currently forecast to reach the region Friday night.

On Monday, ski cutting produced a size 1.5 avalanche with a depth of 25cm.  Explosives triggered a cornice which triggered two size 2 slabs on the slope below.  These were 40cm thick slabs and failed on a north aspect.  On Sunday, skiers and explosives triggered storm slabs up to size 2.5. Typical slab depths were 40-60cm but slabs up to 80cm were reported in wind loaded areas. Multiple remotely triggered avalanches were reported with the furthest being triggered from 100m away. This suggests that the weak layer below the storm slab is very reactive in some areas. On Saturday, isolated natural avalanche activity was reported up to size 2 in the north of the region and skiers triggered avalanches up to size 1.5. On Wednesday, lingering storm slabs are expected to be reactive to human-triggering, especially in steep alpine terrain and wind-loaded terrain features. The sun is expected to trigger some natural activity on steep solar aspects including both loose wet avalanches and slab avalanches. Cornices will become weak in the afternoon and natural cornice falls have the potential to trigger large slabs.

In the north of the region, 20-60cm of recent snowfall overlies a weak layer that was buried on Friday. This weak layer typically consists of surface hoar and facets overlying a melt-freeze crust that exists everywhere except high elevation north-facing terrain. In exposed alpine terrain, strong SW winds have redistributed the recent storm snow forming thicker wind slabs in leeward features. Large cornices exist in the alpine and may become weak with daytime warming. There are three dormant persistent weak layers that we are continuing to track. The late-March crust is down 50-70cm and was reactive last week during the warm period. The mid-March and mid-February layers are typically down between 70 and 100cm and have been dormant for several weeks. These layers have the potential to wake up with sustained warming, a significant rain event, and/or a big cornice fall.