Avalanche Forecast

Issued: Mar 8th, 2014 7:24AM

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

Peter, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Tonight and Sunday: Heavy precipitation overnight (25-40 mm) drying out during the day. Expect a mix of sun and cloud Sunday. The freezing level should peak around 1600-1800 m, then drop to 1500 m. Winds are moderate to strong from the W-SW. Monday: Cloudy with sunny breaks and possible flurries. The freezing level is around 1200 m. Winds are light from the west. Tuesday: A mix of sun and cloud. The freezing level is around 1200 m and winds are light and variable.

Avalanche Summary

Several intentionally skier triggered slab avalanches up to size 1.5 were reported on Friday. These were within the recent storm snow. Expect the size and likelihood to have increased later on Saturday as snow accumulated. Natural slab avalanche activity should start to taper off on Sunday as conditions dry out; however, if the sun does poke out it could kick off a wet loose cycle on solar aspects and possible cause fresh cornice tabs to pop off.

Snowpack Summary

Another moist and mild storm was just starting to affect the region at the time of writing. It looks like this system could add another 30-60 cm of dense storm snow with very strong southerly winds. We could also see rain up to 1800 m near the coast. This adds to the previous 30-60 cm of rapidly settling storm snow late last week. Expect to find various storm snow instabilities and thin crusts within the recent snow. The early March melt-freeze crust is now down roughly 90-150 cm. This layer was found on all aspects at treeline and below, and on all but North aspects in the alpine. There are no new snowpack tests on this layer to report, but the continued loading and mild temperatures should help this weakness heal. The mid February crust/facet combo appears to be rounding and bonding in areas where it is buried 150 cm or deeper. In shallow snowpack areas, where the weak layer is buried less than 100 cm deep, it continues continue to fail with popping shears in snow profile tests. Big un-supported alpine North aspects are the most likely place to find (and potentially trigger) this well preserved weak layer.

Problems

Storm Slabs

Weaknesses may exist within or under the new storm snow. Also, expect deep and dense wind slabs in exposed NW through E facing terrain at and above treeline.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Persistent Slabs

Heavy loading could be enough to trigger the mid-February facet/crust combo, particularly on northerly aspects. Step down avalanche are possible.

Avoid lingering in runout zones.>Be aware of the potential for large, deep avalanches.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Loose Wet

Rain will probably saturate the upper snowpack as high as 1800 m. There's also a chance the sun will poke out on Sunday, potentially kicking off a loose wet cycle on solar aspects.

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: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 9th, 2014 3:00PM