Avalanche Forecast

Issued: Apr 1st, 2014 10:03AM

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.

Use increased caution during afternoon warming, especially on sun exposed slopes.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Wednesday

Weather Forecast

Synopsis: The South Coast should remain mostly dry under the ridge of high pressure until Thursday evening when a more potent front makes landfall.Wednesday: Freezing Level: 1400m - 1700m; Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Moderate, NWThursday: Freezing Level: 1100m - 1600m; Precipitation: Trace; Wind: Treeline: Light, S | Ridgetop: Moderate, SWFriday: Freezing Level: 1100 - 1800m; Precipitation: 1:10mm - 1:15cm; Wind: Treeline: Moderate, SW | Ridgetop: Strong W/SW

Avalanche Summary

Warming temps drove a natural avalanche cycle to size 3 on Monday. It's important to note that many of these large avalanches were running on shady N-NE facing slopes between 1900 - 2200m. Several smaller loose snow avalanches to size 2 were running in the recent storm snow on all aspects too.

Snowpack Summary

Daytime high temperatures are hovering near zero as high as 1900m. Moist snow to 1600m was reported on Monday.The weekend storm produced 15 - 70 cm of new snow. A gentle melt/freeze cycle Sunday and Monday is helping this snow to bond to the underlying melt freeze crust that exists below 2100m, on all aspects with the exception being north facing terrain above 1500m where the crust is not present. The first part of the storm was accompanied by strong southerly winds that formed Isolated wind slabs immediately below ridge crest. This snow adds additional load to the mid March surface hoar / crust interface, now down 80 - 110cm. The bond at this interface is improving making it less susceptible 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 wind slabs immediately lee of ridge crest that may still be sensitive to human triggering. The strong spring sun has the potential to initiate both small loose and large storm slab avalanche activity on all aspects.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Deep Persistent Slabs

Two deep weak layers exist in the snowpack. These weak layers could be activated by warming temps, cornice fall, a smaller avalanche in motion, or a rider finding the sweet spot.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 2nd, 2014 2:00PM