Avalanche Canada jsmith, Avalanche Canada

South Columbia Avalanche Forecast

Apr 23rd, 2019 3:45PM

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

Lingering wind slabs may still be reactive to human triggers; especially on lee features below alpine ridgetops.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Mostly cloudy with isolated alpine flurries; 1-3 cm / Light, westerly winds / Alpine low -3 C / Freezing level 1500 m.

WEDNESDAY: Mix of sun and cloud / Light, northwesterly winds / Alpine high -1 C / Freezing level 1800 m.

THURSDAY: Sunny / Light, southwesterly winds / Alpine high 2 C / Freezing level 2100 m.

FRIDAY: Cloudy with isolated alpine flurries; 1-3 cm / Light, southwesterly winds / Alpine high -1 C / Freezing level 1800 m.

Avalanche Summary

No new avalanches were reported in this region on Monday. However, 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.

On Saturday, numerous natural loose wet avalanches up to size 1.5 were reported on all aspects/elevations.

On Friday, Numerous loose wet and slab avalanches to size 2.5 on all aspects in the alpine were reported. Although not in this region, check out these two MINs from Saturday in Glacier National Park HERE. and HERE

Snowpack Summary

20-30 mm. of rain has soaked the snowpack at treeline and below. The rain/snow boundary on Friday was around 2200 m. New snow amounts in the alpine will taper rapidly with elevation and likely equate to around 15-25 cm of moist snow at upper elevations adding to the 20-40 cm recent snow which overlies a crust everywhere except high elevation, north facing terrain where preserved surface hoar (weak, feathery crystals) may be present in isolated locations down 30-60 cm. A similar layer buried in early April is down 50-80 cm. Smaller storm slab avalanches may step down to one of these deeper weak layers.

Below treeline, snow is disappearing rapidly.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Lingering wind slabs may still be reactive to human triggers; especially on lee features below alpine ridgetops.

  • Use small slopes without consequence to test the bond of the recent snow.
  • Pay attention to changing conditions with elevation/aspect.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine.

Loose Wet

An icon showing Loose Wet

Likelihood

Possible

Expected Size

1 - 2

Strong solar radiation may trigger loose wet avalanches on steep terrain; especially at upper elevations where there is new snow.

  • A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
  • Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.

Aspects:

North East, East, South East, South, South West, West, North West.

Elevations:

Alpine, Treeline.

Valid until: Apr 24th, 2019 2:00PM