Avalanche Forecast

Issued: Apr 20th, 2013 10:30AM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet, Cornices and Wind Slabs.

jlammers, Avalanche Canada

Sea To Sky.

Monday is the last day of the 2012/13 forecast season. As of Tuesday, general spring messaging will be found under the "Forecast Details" tab.

Summary

Confidence

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

Weather Forecast

Sunday: Overcast skies with clearing in the afternoon / Light and variable winds / Freezing level at about 1500mMonday: Generally clear skies / Light north winds / Freezing level at about 1800m

Avalanche Summary

Avalanche control on Friday produced slab avalanche results to size 1.5. I would expect a shift from new snow instabilities to wet loose activity with forecast sunny skies.

Snowpack Summary

Variable amounts of snow fell throughout Thursday night and Friday with the greatest accumulations falling in the south of the region. More recent rain and warm temperatures have left snow surfaces moist to about 1950m. Cohesive new wind slabs exist at higher elevations.In the upper snowpack (down 50-70cm) a significant melt-freeze crust lingers. Some facetting has been observed above and below this crust. At the same interface spotty surface hoar may linger on high, sheltered north facing terrain. My best guess is that this interface has gained significant strength, although I would make further observations before committing to any steep, unsupported features in the alpine.Cornices are huge and will continue to grow with the forecasted precipitation.

Problems

Loose Wet

Watch for loose wet avalanche activity in steep terrain, especially if the sun comes out on Sunday.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Cornices are gigantic and may become weaker with forecast sun.

Pay attention to overhead hazards like cornices.>Stay well back from cornices.>

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 6

Wind Slabs

Recently formed windslabs have likely gained significant strength; however, human triggering may be possible on unsupported terrain at higher elevations.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 21st, 2013 2:00PM