Avalanche Forecast

Issued: Apr 1st, 2014 10:07AM

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

South Coast.

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 and 2500m. Included in this cycle was a size 3 at 2500m on a steep north facing slope that is suspected to have released on one of the deep persistent weak layers. Several smaller loose snow avalanches to size 2 were running in the recent storm snow on all aspects too.

Snowpack Summary

The weekend storm produced 30 to 50cm in the north and around 30 cm in the south. Mild temperatures and solar radiation on Monday/Tuesday are likely causing settlement of the storm snow and melting of the snow surface on most slopes expect maybe steep north aspects in the alpine. This settlement 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.The persistent weak layers from early March and early February continue to be a concern. The March melt-freeze crust/surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm and may still be triggered by heavy loads like cornice falls or storm slab avalanches in motion. Avalanches releasing on these layers may step down to the ground during periods of strong solar radiation or warm spring rain.

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.

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

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 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

Unlikely - Possible

Expected Size

3 - 6

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