Date issued

Apr 23, 2018 - 4:23 PM

Valid until

Apr 24, 2018 - 4:00 PM

Prepared by

jasper snow safety

Solar triggered avalanches and cornice failures will increase in frequency the next few days as each day will be warmer than the previous. Temperatures expected to spike Wednesday and Thursday.

Regular season
Monday - April 23, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Below Treeline

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Tuesday - April 24, 2018
Alpine

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Treeline

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Below Treeline

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Wednesday - April 25, 2018
Alpine

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Treeline

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Below Treeline

4 - High

Very dangerous avalanche conditions.Travel in avalanche terrain not recommended.

Natural avalanches likely;human-triggered avalanches very likely.

Large avalanches in many areas;or very large avalanches in specific areas.

Avalanche Problem 1: Loose Wet

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

The next few nights and days will be progressively warmer increasing the probability of loose wet avalanches. Start and end early plus be vigilant of overhead hazard as these avalanches have been gaining mass and running far.

Travel and Terrain Advice
  • Use extra caution on solar slopes or if the snow is moist or wet.
  • If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.

Avalanche Problem 2: Persistent Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Triggering this slab would have serious consequences. Cornice failures are acting as triggers.

Travel and Terrain Advice
  • Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
  • If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.

Avalanche Problem 3: Cornices

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Rising temperatures are causing cornices to fall triggering slopes below. Give them a wide berth.

Travel and Terrain Advice
  • Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.
  • Avoid steep slopes below cornices.

Avalanche Summary

Monday there was a report of a size 2 above upper weeping wall stopped at the trees. Another size 2 was noted on the Churchill slide path. Things are waking up with the rising temperatures. Sunday size 2 slab avalanche occurred on the E slopes of Lectern, initiating in the alpine and running to treeline. Loose wet activity is also increasing.

Snowpack Summary

Sun or temperature crusts extend to treeline and into the alpine on southerly slopes. Persistent slabs can be found on most aspects at treeline and above. These have been reactive to large triggers like cornice failures. Below 1,900m the snowpack is going isothermal on a daily basis.

Weather Forecast

Tuesday will be sun and cloud, no snow, high of 3 C, light winds, and 2600m or higher freezing level. Wednesday will be similar but warmer and with a slightly higher freezing level. Thursday will be sunny and very warm with freezing level up to 3600m and 10 C temperatures.

Danger Ratings Explained

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Natural avalanches possible; human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

4 - High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human-triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

5 - Extreme

Avoid all avalanche terrain.

Natural and human-triggered avalanches certain.

Large to very large avalanches in many areas.

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