Regions
Banff Yoho Kootenay.
The temperature will rise significantly, peaking on Tuesday. Windslabs remain very touchy. Wind-back aggressive terrain choices until we are through the warming period.
Weather Forecast
A warming trend will influence the region starting tomorrow and peaking on Tuesday with the freezing level potentially rising to 3200m. This will be accompanied by clear skies. Expect intense solar radiation during this period as well. This weather pattern will elevate the danger rating significantly.
Snowpack Summary
Wind slabs exist in the alpine and at tree line that are easy to trigger. The Jan 6 surface hoar/facet/sun crust layer, down 40-100cm, is becoming less reactive to skier triggering, however sudden collapse results persist on the Jan 6 and Dec 3 layers. Isolated whumphing on mid-pack facets/surface hoar have been observed this past week.
Avalanche Summary
We received a reliable report that two of the Healy Creek slide paths went size 3 sometime yesterday during or after the storm. Debris came within 50m of the trail in both occasions. Additionally, visitor safety staff observed a size 2.5 avalanche in the Mt. Whymper slide paths on highway 93S, it ran for approx 700m.
Confidence
Freezing levels are uncertain on Tuesday
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.