Avalanche Forecast

Issued: Mar 29th, 2014 10:01AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Deep Persistent Slabs.

ghelgeson, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Synopsis: A weakening upper trough stalled off the southern BC coast should continue to deliver light snowfall Saturday night and scattered very light snowfall on Sunday. Look for gradual clearing on Monday.Saturday Night: Precipitation: 1 - 6mm | 2 - 10cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SWSunday: Freezing Level: 1100m - 1200m; Precipitation: 0 - 2mm | Trace; Wind: Treeline: Light, SW | Ridgetop: Light, SWMonday: Freezing Level: 1300 - 1600m; Precipitation: Nil; Wind: Treeline: Light, SW | Ridgetop: Light, WTuesday: Freezing Level: 1200 - 1700m Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Light, NW

Avalanche Summary

On Friday small pockets of wind slab were sensitive to human triggering. I suspect activity ramped up Friday night into Saturday.

Snowpack Summary

New snow accompanied by strong southerly winds has likely formed fresh sensitive wind slabs in wind exposed terrain, and storm slabs that extend down into the treeline vegetation band. This snow adds additional load to the mid March surface hoar / crust interface, now down 80 - 110cm. The bond at this interface is improving, but it may still be sensitive to human triggering. The early-March crust/facet layer is down about 100-150 cm and the early February layer is now down close to 200 cm. These layers are largely dormant at this time.The lower snowpack is strong and well settled.

Problems

Storm Slabs

Watch for fresh sensitive wind slabs, which should be most problematic immediately lee of ridge crest and mid slope features. The new snow will need another day or two to settle before we start to think about the bigger objectives.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid freshly wind loaded features.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>The new snow will likely require another day to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

Two deep weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a surface avalanche in motion, or a rider finding the sweet spot, likely near a rock outcropping, or anywhere the snowpack goes from thick to thin.

Be aware of the potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Extra caution needed around cornices with current conditions.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 30th, 2014 2:00PM