South Coast

We'll soon be moving from a storm slab problem to a persistent slab problem. Check out this blog post for thoughts on the current situation and strategies for the next the chapter.

Fair - Timing, track, or intensity of incoming weather system is uncertain

The bulk of the Pacific fronts should have passed mid-day Friday, although there may be some small "squall" precipitation events before the area cools down and clears off. Cold weather in the forecast for early next week.Thursday night: Freezing level at valley bottom, light flurries with possibility of 5 to 10cm in the forecast. Winds at ridge top gusting to50 Km/h.Friday: Freezing level around 100m , no precipitation in the forecast.  Cool dry air moves into the region, ridge top winds up to 50Km/h.Saturday: Freezing level around 100m,  no precipitation, ridge top winds from the north @ 25 Km/h.Sunday: Freezing level at or near  valley bottom, another pulse of moisture with a possible 10 to 15 cm of precipitation,  ridge top winds around 20 Km/h.

Lots of natural avalanches running in the forecast region, with the Coquihalla having a large natural avalanche cycle in the past 48 hrs with a "whopper" size 4 avalanche today. Some of these avalanches were in places not normally seen to run except on a 10 to 15 year cycle. Popular ski routes have had natural activity as well. A cornice failure earlier in the week triggered a size 2.5 slab avalanche on the slope below and explosives control has produced numerous very large avalanches.

In the last week, the northern parts of the region have received over 1m of new snowfall and the Southern areas have seen almost 2m. The Coquihalla has received 35 cm of new snow in the past 24hrs with high winds, adding to the existing storm slab now 80 to 180cm deep in some parts of the region. In the southern portion of the region the slab sits on a crust/facet combination along with old wind slabs on lee slopes. In the northern part of the region one can add surface hoar to the crust/facet/slab combination. The storm slab seem to be unusually reactive at tree line and below tree line elevations. Whumpfing and widespread natural avalanche activity are a sign of a poor bond between the new snow and these old surfaces. Strong to extreme winds are redistributing the new snow into deeper, reactive wind slabs on the lee side of ridge tops.The mid and lower snowpack are generally strong and well-settled. Although basal facets and depth hoar are likely to exist in the north of the region, giving us a low probability, but high consequence of a large destructive avalanche.