Tricky conditions exist due a complex snowpack and a touchy weak layer. Conservative terrain selection is still critical.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
On Wednesday evening, the first of 2 organized fronts will move through the region bringing 5-10cm of new snow and strong southwest winds. Thursday will see mainly overcast skies and continued strong ridgetop winds. By Friday evening, the second front will pass through the region. Expect another 5-10cm of snow and strong southwest winds. Freezing levels should remain at valley bottom for Wednesday and Thursday, and then rise to about 1500m for Friday.
Avalanche Summary
On Sunday, a helicopter is believed to have remotely triggered a size 2.5 persistent slab avalanche at the 1900m elevation from a distance of 200m. The slab was about 400m wide, 90cm deep and is thought to have failed on the early January surface hoar. Although this avalanche occurred on the east side of Highway 5 (technically in the Northern Monashees), similar touchy conditions likely exist in many parts of the Cariboos. With that, a few size 1 naturally triggered persistent slab avalanches were also noted in the Cariboos on Monday on a northeast aspect at 1600m. The early January surface hoar was the culprit in both of these slides.
Snowpack Summary
Snowfall and strong winds prior to last weekend created wind slabs that may remain sensitive to light inputs in higher elevation lee terrain. The touchy layers of surface hoar from early January are now typically down 70-120cm and are variably reactive. In other words, some slopes are difficult to trigger while remote triggering continues on other features. These layers have the potential for wide propagations, and smaller avalanches have the potential to step-down to one of these layers. The mid and lower snowpack are generally strong and well settled below these layers. Snowpack depths are variable across the region and shallow snowpack areas may have weak facetted crystals near the ground.
jlammers,
Avalanche Canada
