Avalanche Forecast

Issued: Apr 6th, 2016 8:39AM

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

pmarshall, Avalanche Canada

Purcells.

It will almost feel like summer for the next couple days. The heat and sunshine will cause the avalanche danger to rise during the day, especially on solar aspects. Choose terrain carefully.

Summary

Confidence

Moderate

Weather Forecast

THURSDAY: Becoming mainly sunny. The freezing level shoots up to 3400 m. Winds should ease to light and variable. FRIDAY: Mainly sunny. The freezing level stays well above 3000 m and winds should remain light. SATURDAY: A mix of sun and cloud. The freezing level could drop to 2500 m and winds could kick up to moderate from the west.

Avalanche Summary

A couple small skier-triggered wind slabs (size 1) were triggered in steep wind-loaded terrain on Tuesday. One size 2.5 slab avalanche was observed near Golden on Monday. This wet slab was accidentally triggered by skiers late on Sunday on a sun-exposed alpine slope. Expect loose wet slides, natural cornice falls, and the potential for isolated persistent slabs on Thursday.

Snowpack Summary

A dusting of new snow sits on a melt-freeze crust at all elevations and on all aspects. The exception to this could be high north-facing slopes where cold dry snow might still exist. Forecast snow and wind on Wednesday may have created fresh pockets of wind slab in lee alpine terrain. The March 22nd rain crust is 30-40 cm deep and is present to around 2000 m. The late February persistent weak layer is now down 40-100 cm below the surface. Both of these persistent weaknesses could wake up again as temperatures soar and the sun returns later this week.

Problems

Loose Wet

Rapid warming and strong spring sunshine are a perfect recipe for loose wet avalanche activity in steep terrain.

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.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Cornices

Cornices could fail easily during the day when temperatures soar and the sun reappears.

Do your best to avoid traveling on or underneath cornices. If you have to, move quickly and only expose one person at a time.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

Persistent Slabs

Intense solar radiation, a heavy wet surface sluff, or a cornice fall could be enough to trigger lurking deep weaknesses.

A few different buried persistent weak layers (PWL's) are lurking in our snowpack which means there is potential for large destructive avalanches that have the capability to run full path.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Apr 7th, 2016 2:00PM