Avalanche Forecast

Issued: Mar 28th, 2014 11:25AM

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

ghelgeson, Avalanche Canada

Sea To Sky.

Forecast snow amounts are uncertain. If snow amounts at treeline exceed 20cm, the danger will likely be high there too.

Summary

Confidence

Poor - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A broad upper level trough settles in over the Southern Coast which should generate significant precipitation through the weekend. Precipitation amounts have varied wildly from run to run. The amounts shown below are my best guess, but I won't be surprised if the region receives more.Saturday: Freezing Level: 600m rising to 1300 - 1500m Precipitation: 5 -15mm | 5 - 20cm; Treeline Wind: Light, South | Ridgetop Wind: Strong, SouthSunday: Freezing Level: 500m rising to 1200 - 1500m Precipitation: 2-5mm | 2-10cm; Treeline Wind: Moderate, SW | Ridgetop Wind: Strong, SWMonday: Freezing Level: 400m rising to 1400 - 1800m; Precipitation: Trace; Treeline Wind: Light, SE | Ridgetop Wind: Light, SE

Avalanche Summary

No new reports of avalanches.

Snowpack Summary

The recent snow is expected to settle and bond to the mix of old surface crusts and wind slabs with daytime warming and overnight freezing levels dropping down to near valley bottoms. The forecast new snow and strong Southwest winds are expected to develop new storm slabs over the next few days that may release down to the old surface of melt-freeze crusts and/or where facets are sitting on old wind slabs. The added load of storm snow or storm slab avalanches in motion may trigger the March persistent weak layer. The early-March crust/facet layer is down about 100-150 cm and the early February layer is now down close to 200 cm.

Problems

Storm Slabs

New snow and wind should create fresh slabs that increase in sensitivity to triggering as the day goes on. Slopes immediately lee of ridge crest will likely be the most problematic. The new load may activate the old storm interface too.

Minimize exposure during periods of heavy loading from new snow, wind.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

Forecast snow and wind may develop fresh new cornices that could fall off naturally and trigger the deeply buried weak layers. Storm snow avalanches in motion may also trigger these weak layers resulting in very large avalanches.

Be aware of the potential for large, deep avalanches.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 29th, 2014 2:00PM