Avalanche Forecast

Issued: Mar 28th, 2016 4:00PM

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

garth lemke, Parks Canada

Jasper.

Despite the moderate rating the forecasters do not have much confidence in this snowpack. The spatial variability and shallow nature adds to the complexity. There is a low probability of triggering but severe consequences if you get it wrong.

Summary

Weather Forecast

Expect Monday night light flurries and -9. Tuesday will be freezing level of 2300m and variable clouds. A good overnight freeze Tuesday night and Northerly light winds. Wednesday and Thursday night there will be no freeze hovering around 2300m. Wednesday-Thursday will be very warm, sunny, and continued light North winds.

Snowpack Summary

Cold overnight temps and warming by midday is creating spring like snowpack and surface crusts. Significant variation in snowpack depth through-out the forecast area but generally shallow and below threshold in valley bottoms. Weak basal depth hoar exists. Maligne/Whistler creek areas less snowpack and higher spatial variability.

Avalanche Summary

Shooting cracks in the Maligne lake Bald Hills flats a result of surface crust over weak facets and shallow conditions. Loose wet slides on solar aspects in the south end of the park occurred on Friday with high temperatures. Saturday observed size 2.5 on SW'ly aspect near the Boundary and large serac collapse on the north glacier of Mt. Athabasca.Â

Confidence

Freezing levels are uncertain on Wednesday

Problems

Deep Persistent Slabs

This problem has been most active in the Whistler/Portal Creek area but is widespread through the forecast region. When triggered, it will be big with serious consequences. Warm and sunny conditions will increase this danger.

Be aware of thin areas that may propogate to deeper instabilites.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Cornices

Some cornice failures are being noted. It can act as a large trigger initiating deep weaknesses plus their sheer mass, whether or not it initiates an avalanche, would be like being hit by a car.

Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.Cornices become weak with daytime heating.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Wet

This problem will increase with forecasted warm temps and intense solar radiation. The danger rating will rapidly increase particularly on thin snowpack zones and sun facing slopes.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid ice climbs that are exposed to steep rocky terrain on solar aspects.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Mar 29th, 2016 4:00PM