Archived

Avalanche Forecast

Jan 21st, 2016–Jan 22nd, 2016

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

Wait a couple days to gather more post-storm information before venturing out into bigger terrain.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Tonight and Friday: Rain or snow ending in the morning (20-30 mm), then cloudy. The freezing level dips from 2000 m to 1400 m. Winds are moderate SE easing to light from the SW. Saturday: Cloudy with sunny breaks. The freezing level is around 1200 m and winds remain light from the W-SW. Sunday: Cloudy with sunny breaks. The freezing level is around 1000 m and winds are light from the S-SW.

Avalanche Summary

We will have to wait a day or two to determine how extensive the avalanche cycle on Thursday was. My guess is that we saw widespread activity at all elevations with slides up to at least size 3. Natural activity should taper off heading into the weekend. Hopefully the buried surface hoar problems were cleaned out, but I would treat any slope that did not release as being suspect, especially at treeline.

Snowpack Summary

The upper snowpack may look quite different after Thursday's storm. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading from snow (and potentially rain) may have flushed-out the mid- and early-January surface hoar/facet layers that were buried 60-100 cm deep. However, don't rule these layers out right away. It may still be possible to trigger shallow slopes that did not release naturally. Rain has probably saturated the upper snowpack on lower elevation slopes (below 1500-1800 m).The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.

Avalanche Problems

Storm Slabs

Continued snowfall on Thursday night at higher elevations may prolong the storm slab problem. Watch for deep and touchy wind slabs in lee (NW-NE) and cross-loaded terrain.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Persistent Slabs

Thursday's storm may have helped clean out the mid-January surface hoar problem; however, wait a day or two to reassess the conditions before moving out into steeper terrain.

Be wary of slopes that did not previously avalanche - even on low angle terrain.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 5

Loose Wet

Loose wet sluffs are possible in steep open terrain below treeline where precipitation persists as rain on Friday morning.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3