Avalanche Forecast
Issued: Apr 19th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Cornices and Persistent Slabs.
Ian Jackson,
Tuesday and Wednesday look like beautiful days to be in the mountains. Start and finish your trips early to take advantage of the good overnight freezes.
Summary
Weather Forecast
Tuesday and Wednesday look like beautiful days to be in the mountains. Sunny with light winds and good overnight freezes. Freezing levels will rise to around 2200m both days but the sun is strong this time of year so expect solar aspects to feel warmer than that. Thursday is looking to be cool with light snow.
Snowpack Summary
10-20 cm of new snow on Sunday refreshed the ski quality. This sits on crusts to ridgetop on solar aspects and below 2000m on shaded aspects. Persistent layers in the mid and lower snowpack were re-activated in a few instances during the heating last week producing large avalanches with large loads (cornice failures and explosives).
Avalanche Summary
An avalanche cycle to size 3 occurred with last weeks warm up. Primarily loose wet and cornice triggered avalanches with the occasional larger avalanche failing on persistent layers in the mid and lower pack. Since the temperatures cooled on Sunday, no new avalanche activity observed.
Confidence
Problems
Loose Wet
Clear skies mean solar aspects will start sluffing as the day warms up. These will start small as just the new snow sluffs and gradually get bigger as the surface crusts break down.
- Use extra caution on solar slopes or if the snow is moist or wet.
- Travel early before the heat of the day.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are unpredictable even to experienced forecasters. However, we do know that they are big right now and will fall off before Summer. Some cornices failures last week were enough to trigger the persistent weak layers.
- Cornices become weak with daytime heating, so travel early on exposed slopes.
- Give cornices a wide berth when travelling on or below ridges.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
Cooler temperatures may decrease the likelihood of deeper layers in the mid to lower snowpack being triggered. If there is a poor freeze or one of the many large cornices fails, larger avalanches on these layers are still a possibility.
- Pockets of persistent slabs linger on alpine lee features.
- Pay attention to overhead hazards like cornices which could trigger persistent slabs.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 20th, 2021 4:00PM
