Avalanche Forecast

Issued: Apr 27th, 2014 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Public Bulletins will no longer be provided for the 2013/14 season however avalanche hazard will persist later this year with an above average snowpack. Contact Visitor Safety at WLNP for help with safe trip planning in the spring and summer seasons.

Summary

Weather Forecast

Watch for periods of warming in the form of sun or rain to weaken the surface crusts. If above freezing conditions persist through overnight periods the poor recovery of surface crusts and further heating may affect deeper layers. Spring storms will undoubtedly bring additional snow to the area: watch for new storm and wind slabs to form.

Snowpack Summary

Melt freeze cycles have created surface crusts on all but high North facing slopes. As new snow accumulates over these crusts watch for storm slab and wind slab problems to arise. Cornices have continued to grow with recent storms. The midpack and buried crusts provide strength over the weak basal facets in most areas with deep snowpack values.

Avalanche Summary

Recent local avalanche activity has included loose wet events associated with heating in the form of sun or, at lower elevations, rain. On the larger scene, large events failing to the basal layers continue to be reported as the snowpack loses strength with heating. Cornices and smaller avalanches are potential triggers for this type of event.

Confidence

Problems

Loose Wet

Even short bursts of solar heating can rapidly affect the snow this time of the year. With mild temperatures in the forecast, watch for rain to affect the snow at lower elevations.

Travel early on frozen crusts before the heat of the day.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

Expected Size

1 - 2

Storm Slabs

As spring storms continue to bring additional snow watch for new storm and windslabs to form over surface crusts

Avoid freshly wind loaded features.The new snow will requires several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

Sustained heating will weaken the upper snowpack as the days become warmer and the weak basal layers are likely to allow for some large avalanches. Remember cornice failures and smaller avalanches hitting a slope could trigger these serious slabs.

Pay attention to overhead hazards like cornices.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Apr 28th, 2014 4:00PM