Wednesday February 19, 2020

Wednesday February 19, 2020
Thursday February 20, 2020
Friday February 21, 2020
Confidence: High - Good model agreement and numerous field observations and reports.

Main Concerns

Loose Wet, Wind Slab - view Avalanche Problems for detailed information.

Travel & Terrain Advice

Careful and cautious route finding when entering into or over convex rolls or steep features.

Monitor surface snow conditions to determine the effect of warming and solar.

Plan to avoid during daytime warming terrain traps such as cliffs, trees and gully features that will magnify the effect of being caught in a small loose wet avalanche.

Avoid traveling both above and below cornice features.

Avalanche Summary

No new avalanches observed or reported.

Avalanche Problems

Loose Wet

Daytime warming and the suns effect on surface snow will cause snow to become unconsolidated especially on south aspects. This avalanche problem when triggered is likely to remain small and on isolated terrain features that are steep and direct solar,it will be possible for a small avalanche to gain mass and result in a large size 2 avalanche.

Location: On all south aspects and found at all elevations.

Possibility: Triggering of this avalanche problem is possible from light loads such as skiers. Natural avalanches are unlikely to possible.

Size: If triggered expect these avalanches to be small, and on isolated terrain features large, size 2.

Wind Slab

Found on predominantly North aspects, but can still be found on all aspects. Past weather has promoted settlement of this problem, but it is still lurking in areas where past winds has deposited low density snow.

Location: All aspects in both the Alpine and at Treeline.

Possibility: Triggering of this avalanche problem is possible from light loads such as skiers. Natural avalanches are unlikely.

Size: If triggered expect these avalanches to be small, and on isolated terrain features large, size 2.

Snowpack Summary

Daytime warming with freezing levels up-to 1500 meters and periods of sun is continuing to settle the snow pack. The surface snow on solar aspects at all elevations is becoming moist with warming temperatures and has seen the development of a sun crust.

Alpine and Treeline elevations with exposed ridge tops are scoured down to the Jan 31 melt freeze crust, the crust is supportive to ski penetration. Non solar protected areas still have some preserved and dry snow and surface hoar is beginning to form and survive the daytime melt.

The Jan 31 melt freeze crust can be found down as deep as 30 cm and is continuing to bond well. The mid and lower snow-pack is well settled and dense with a few interfaces that are not concerning but are still detectable.

Snowpack Details

SurfaceVariable surfaces conditions range from moist on solar aspects to hard packed and scoured on exposed terrain. Surface hoar has been observed on north aspects and is surviving the daytime heat.
UpperA supportive and reactive melt freeze crust down from 15 to 30 cm.
MidA variety of old crusts can be found.
LowerWell settled and dense.

Past Weather

A pacific high pressure has kept the weather machine mostly quiet, clear sky with some fog and afternoon convective clouds. Temperatures have remained cool overnight with freezing levels near sea level and daytime warming causing freezing levels to rise to the 1500 meter mark.

Weather Forecast

A high pressure to the north east of the island continues to hold on, it will however begin to dissipate and lose strength near the end of this forecast period. Expect clear and sunny sky, little precipitation and overnight cooling with freezing levels dropping to sea level. Daytime freezing levels are expected to reach 1200 meters during periods of daytime warming. Daily low level cloud banks and valley fog are likely with a weak temperature inversion possible.

Beginning Friday, the high pressure will begin to deteriorate; this will allow for storm systems to penetrate the region with an expectation that precipitation in the form of snow will begin to fall on the Island mountain ranges this weekend.

Wednesday: No new snow, Winds Moderate from the South East, Freezing levels to 1200 meters.

Thursday: No new snow, Winds Moderate from the South East, Freezing levels to 1200 meters.

Friday: No new snow, Winds Moderate from the South East, Freezing levels 1200 meters.

Posted on Wednesday February 19, 2020 by Jesse Percival

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