Avalanche Forecast

Issued: Feb 10th, 2018 4:37PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Cornices.

jmcbride, Avalanche Canada

Sea To Sky.

Reactive wind slabs can be found on leeward and cross-loaded slopes at upper elevations. Also be mindful of what is above or below you. Cornices may become fragile especially with warming or sun-exposure.

Summary

Confidence

High -

Weather Forecast

SUNDAY: Mostly sunny. Ridge wind light, northeast. Temperature -8. Freezing level valley bottom.MONDAY: Sunny. Ridge wind light, northwest. Temperature --5. Freezing level 800 m. Alpine inversion.TUESDAY: Mostly cloudy, flurries. Accumulation up to 5 cm. Ridge wind moderate, southwest. Temperature -2. Freezing level 800 m. Alpine Inversion.

Avalanche Summary

Saturday a skier triggered a a size 1.5 wind slab release from a cross-loaded feature on a northwest aspect at 1900 m, near Whistler.On Friday, evidence of a natural cycle which likely occurred near the end of the warming period earlier in the week was reported, with storm slab activity up to size 3 observed on north to east aspects in the Mt Currie area.On Thursday, avalanche control with explosives triggered numerous slab avalanches up to size 2. Cornice releases triggered wind slabs from the slopes below up to size 1.5. With colder temperatures expected this weekend, natural avalanche activity will likely taper off, but human triggering will be possible especially on leeward and cross-loaded slopes.

Snowpack Summary

Snow surfaces vary from aspect to elevation showing crusts, wind pressed and scoured conditions. In the alpine 5-15 cm of recent snow, accompanied by strong winds from the southeast have formed reactive wind slabs up to 30 cm thick in leeward terrain, while wind-protected areas still hold unconsolidated, cold snow. At treeline and below treeline elevations a melt-freeze crust has formed up to 1900 m.On average 180 cm of settled snow now sits on the mid-January crust which generally shows signs of bonding to the overlying snow; however, it has the potential to "wake-up" with a large trigger such as a cornice fall. Below this, the snowpack is thought to be generally strong and well-settled.

Problems

Wind Slabs

Wind slabs remain reactive to human triggers, especially on leeward slopes and cross-loaded terrain features.

Be cautious as you transition into wind affected terrain.Watch for signs of instability such as whumpfing, or cracking. Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Cornices

Large looming cornices exist along ridgelines. They require respect and discipline. Give them an extra wide berth from above and below particularly during periods of warming or solar exposure.

Falling cornices may trigger large avalanches on the slopes below.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Feb 11th, 2018 2:00PM