Avalanche Forecast

Issued: Jan 23rd, 2015 7:36AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Loose Wet.

triley, Avalanche Canada

Sea To Sky.

The wet, warm, and windy storm will result in High avalanche danger.

Summary

Confidence

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

Weather Forecast

Warm, wet, and windy overnight as another 20-30 mm of precipitation moves into the region. The freezing level is expected to be about 2500 metres overnight and then rise up close to 3000 metres on Saturday. Another 10-15 mm during the day on Saturday with strong Southwest winds, and then another 5-10 mm by Sunday morning. On Sunday the freezing level may start to creep down a bit in the alpine, but still very warm in the valleys. Forecast precipitation for Sunday and Monday are starting to look a bit lower, with 5-7 mm expected on Sunday and 7-10 mm for Monday. Freezing level should remain close to 2400 metres on both days.

Avalanche Summary

Recent avalanche activity progressed from a limited avalanche cycle on Saturday and Sunday (mainly from wind loaded terrain), to several explosive and rider triggered avalanches up to size 2 on Monday and Tuesday. Conditions will start to change heading into the weekend. Warm temperatures and rain is expected to tip off another round of wet avalanche activity on Friday.

Snowpack Summary

Stormy weather is forecast to continue and add to the 50 cm of settled storm snow that sits on a hard crust and/or surface hoar layer. Previous strong W-SW winds redistributed snow in exposed terrain creating deep and dense wind slabs in lee features. The new snow seems to be bonding well to the crust, which is most pronounced between about 1500 m and 2200 m. The distribution of the surface hoar seems spotty across the region, but some operators found it to be widespread in their tenure before it was buried. Deeper snowpack weaknesses have become unreactive, but a recent snow profile highlights the stark hardness contrast between a deep persistent weakness and the surrounding snow. Scenarios like this with deeply buried soft snow surrounded by hard snow aren't confidence inspiring because it all hinges on the strength of the overlying slab, which is often volatile and susceptible to significant warming and loading. Especially with very heavy triggers (like a cornice fall) in the wrong spot (like a thin snowpack area).

Problems

Storm Slabs

Heavy loading from snow and wind could tip off a natural avalanche cycle at and above treeline, especially from wind loaded slopes (N to E facing).

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Loose Wet

Expect wet avalanche activity in steep terrain at and below treeline.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid slopes with glide cracks.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 24th, 2015 2:00PM