Archived

Avalanche Forecast

Jan 5th, 2015–Jan 6th, 2015

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

Regions: Northwest Coastal.

Storm conditions will keep the hazard elevated in the south of the region for the next couple days. Stick to simple, mellow terrain and give the storm snow a few days to stabilize.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The next storm pulse hits the NW on Monday night. Southern parts of the region may see 30-40mm of precipitation whereas the north is around 10-20mm. Alpine wind is expected to be strong from the SW and treeline temperatures are expected to be around -10C. There will be a bit of a break during the day on Tuesday before the next storm pulse hits on Tuesday night. Another 10-20mm is possible for the south and 5-10mm for the north. On Wednesday, a temperature inversion is expected to form and a layer of above-zero air may sit in the alpine. Light precipitation is possible and winds are expected to be moderate from the SW. Thursday looks to be the warmest with freezing levels reaching up to 2500m. The inversion should keep the valleys cooler. Dry conditions are expected on Thursday with light winds.

Avalanche Summary

On Sunday, several natural avalanches were reported. These were primarily wind slabs on W through N aspects and were up to size 3 avalanches. Natural storm and wind slab avalanches are expected to continue on Tuesday and Wednesday as storm conditions continue.

Snowpack Summary

Conditions are highly variable throughout the region. Southern sections near Terrace received around 30 cm of new snow while Bear Pass and Ninginsaw didn't see any new snow on Saturday night. Strong winds are one common theme in all areas though. Ridge winds were cranking from the SE stripping windward slopes bare and probably forming hard or dense wind slabs in lee and cross-loaded areas. A buried surface hoar layer, down 25-35 cm, may be more prevalent in northern sections like Bear Pass and Ninginsaw Pass. The mid December crust can be found down around 40 to 80 cm and is sandwiched with facets and surface hoar. The November crust, down 70 to 175 cm, is gaining strength but is still reactive in some test profiles. The deeper snowpack weaknesses could 'wake up' with heavy loading from new snow and wind.

Avalanche Problems

Storm Slabs

Heavy snowfall and strong winds have built storm slabs in the south of the region. In the northern areas that received less snowfall, wind slabs are the primary concerns.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Persistent Slabs

There are a couple buried persistent weak layers in the upper and mid snowpack, primarily in northern areas like Bear Pass and Ninginsaw Pass. The weight of the new snow may increase the likelihood of triggering one of these layers.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6