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Avalanche Canada jsmith, Avalanche Canada

Purcells Avalanche Forecast

Apr 26th, 2019 4:07PM

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

Last Avalanche Forecast for the season. For additional information check out our Spring Conditions page at: https://goo.gl/cpx8Dq

New snow and moderate winds from a variety of directions may form touchy wind slabs reactive to human triggers.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain

Weather Forecast

FRIDAY NIGHT: Snow in northern part of the region; 5-10 cm. / Moderate, westerly winds / Alpine low -6 C / Freezing level 1400 m.

SATURDAY: Snow (more in the north); 5-15 cm. / Light, westerly winds / Alpine high -5 C / Freezing level 1500 m.

SUNDAY: Sunny / Moderate, northeasterly winds / Alpine high -4 C / Freezing level 1600 m.

MONDAY: Mix of sun and cloud / Light, westerly winds / Alpine high -4 C / Freezing level 1600 m.

Avalanche Summary

On Thursday, several naturally triggered size 2 wind slabs were reported on a variety of aspects in the alpine. There are currently very few professional observers submitting daily observations. Please submit your observations to the MIN. Photos of avalanches or current conditions are particularly useful.

Snowpack Summary

A supportive surface crust caps a mostly isothermal snowpack at lower elevations. In the alpine, the recent snow is likely settling and preserved as cold, wintery, snow on north aspects where reactive wind slabs may still linger. A crust is present on all solar alpine aspects to mountain tops and below 2200 m on all aspects. The strength of the crust will depend on overnight freeze and the speed at which the snowpack warms up during the day.

Weak and sugary faceted grains may remain at the bottom of the snowpack in the alpine, producing a low likelihood but high consequence scenario. Steep, rocky areas with a shallow or highly variable snowpack depth are the most likely places to trigger this layer.

Below treeline, snow is disappearing rapidly.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 2

New snow and moderate winds from a variety of directions may form touchy wind slabs reactive to human triggers; especially in the northern part of the region where more snow is expected.

  • Whumpfing, shooting cracks, and recent avalanches are all strong indicators of an unstable snowpack.
  • Be careful with wind-loaded pockets, especially near ridge crests.
  • Be alert to conditions that change with elevation/aspect.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Possible

Expected Size

1 - 2

Any appearance of the strong April sun can initiate a loose wet avalanche cycle. The likelihood of loose wet avalanches increases as temperatures warm through the day and/or if the sun comes out for a prolonged period of time.

  • Cornices become weak with daytime heating, travel early on exposed slopes.
  • Avoid sun exposed slopes when the solar radiation is strong, especially if the snow is moist or wet.
  • Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Apr 27th, 2019 2:00PM