Avalanche Forecast

Stormy weather eases early on Saturday morning before the next storm arrives on Sunday morning.

FRIDAY NIGHT: Scattered flurries with 10-20 cm of new snow, 30-50 km/h south wind, treeline temperatures around -4 C.

SATURDAY: Flurries end in the early morning hours the a mix of sun and cloud during the day, 10 to 20 km/h northwest wind, treeline temperatures drop to -6 C.

SUNDAY: Heavy snowfall starting mid-morning with 10-15 cm by the evening, 40-70 km/h south wind, treeline temperatures around -6 C.

MONDAY: Another 5 cm of snow by the morning then sunny in the afternoon, light wind, treeline temperatures around -6 C.

Storm slabs were actively growing throughout the day on Friday and will continue to grow overnight. Preliminary reports from Friday suggest the new snow was showing signs of being very reactive, with numerous size 1-2 human and explosive triggered avalanches (30-60 cm thick). Natural avalanches are likely overnight and then as the storm eases on Saturday morning the new snow will be primed for human triggering.

Over the past week there have been a few large isolated avalanches west of Hwy 99 including one on Cloudburst Mountain (see here) and two near Mt. Fee (see here and here). These avalanches may be due to extensive wind loading forming thick wind slabs, but they may also be associated with isolated weak snow from earlier this season.

New snow amounts between Thursday and Saturday morning are expected to total 30-50 cm, with the largest amounts west of Hwy 99. Strong wind will shift from the south to the west, and likely form extra thick slabs in lee terrain. The new snow will overlie a melt-freeze crust up to roughly 1600 m and higher on sun-exposed slopes or dry snow on northerly aspects at high elevations. The bond of the new snow to this interface is suspect, and it may take more time than usual for storm slabs to stabilize.

Around 150 to 300 cm of consolidated snow may overly sugary faceted grains formed earlier this season. These layers are expected to be spotty around the region and we haven't received conclusive evidence of them being the culprit of avalanche activity. That being said, it is possible they may be associated with a few recent large avalanches around the Whistler area.

Remember that cornices along ridgelines are large at this time of year and always have the possibility of failing naturally or from the weight of a human.

• Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
• Use careful route-finding and stick to moderate slope angles with low consequences.
• Avoid freshly wind loaded terrain features.
• Closely monitor how the new snow is bonding to the old surface.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.