Avalanche Forecast

Issued: Jan 17th, 2014 8:39AM

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

jfloyer, Avalanche Canada

South Coast.

The possibility exists for a large avalanche to run on deep weak layers due to the impact of warm temperatures and solar activity.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

The weather pattern is currently dominated by a strong upper ridge of high pressure giving dry conditions.Saturday: Slightly cooler air is expected to move in to this area through the day. Alpine temperatures will become considerably cooler, although still warm in the range of 0 to 5C. Winds are expected to pick up becoming moderate SW by the end of the day.Sunday: A cooler day with alpine temperatures around 0C. Winds should become light. Monday: Alpine temperatures once again climbing to +5 or possibly higher. Light winds.

Avalanche Summary

On Thursday, a natural avalanche occurred on the SE face of Mt. Rohr, size 2.5, running to mid runout on basal facets. On Wednesday, explosive control in the North Cascades produced a couple size 2.5 on N and NE aspects. In the same area, there was also some loose wet avalanches below treeline up to size 1. In the Northern part of the region, there was also report of remotely triggering a couple size 2 avalanches which would have run on basal facets in the alpine on NE aspects.

Snowpack Summary

Very warm alpine temperatures have created a moist snow surface. Previous winds have scoured windward slopes and sculpted sastrugi in exposed areas. Initially, the bond below the most recent storm snow was weak. However, settlement due to the warm temperatures appears to have settled the upper snowpack and it has appeared to have gained strength.There are two lower layers of note near the base of the snowpack. A facet/crust combo from late November (down approximately 100-120 cm) is still giving "sudden" results in compression tests and exists at treeline and alpine elevations. Facets and depth hoar likely still exist at the base of the snowpack, especially in areas where the snowpack was particularly shallow early on in the season. The most likely places you would find this problem is in the alpine in shallow rocky areas, and it has been most widely reported from the Duffey Lake and Chilcotin areas.

Problems

Deep Persistent Slabs

Heavy triggers such as a moist/wet avalanche or a cornice drop could step down to deeper instabilities.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Loose Wet

Warm alpine temperatures could destabilize the snow surface on all aspects but especially on SE and S aspects. Loose avalanches could trigger larger slab avalanches.

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

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 18th, 2014 2:00PM