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Avalanche Forecast

Archived

Jan 25th, 2012–Jan 26th, 2012

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Columbia.

Confidence

Good - -1

Weather Forecast

A weak system will bring a few cm's to the region Wednesday night into Thursday morning. High pressure then works its way up from the States which will keep things fairly dry Thursday afternoon into Friday. There will be broken clouds as NW flow remains aloft, the occasional flurry may even develop, but we shouldn't see any significant accumulations. Winds will ease up a bit Thursday, but they will still be strong out of the NW at ridgetop. @ 1500m expect a daytime high of -3 with an overnight low of -7 Thursday.

Avalanche Summary

Natural activity quieted right down on Tuesday, but I expect there will be plenty of action to report from Wednesday.

Snowpack Summary

An additional 15 – 30cm sits just above the weekend’s 30 – 70 cm. This recent storm was accompanied by big winds out of the S, SW blowing strong gusting to extreme. Observers report that the weekend snow is slowly bonding & settling, but, RP shears are still being reported in the storm snow. This meter or so of storm snow is now sitting on facets created by the cold snap last week. We often think of super cold temperatures as driving faceting, and that’s right, but the faceting mechanism actually occurs much slower at very cold temperatures like the ones we experienced last week. There’s been very little activity at this interface thus far. We’ll see what results come back from the field Wednesday. If it doesn’t perform with the additional load of Tuesday’s storm snow, then it likely won’t in the future either. Time will tell. In my mind, the layer of concern continues to be the Jan 13th SH/FC layer which is now buried 100 – 130 cm in depth. For Thursday I’m bringing the danger ratings down to C, C, C. It’s “scary” considerable, as the potential for large deep avalanches to size 3 exists in the Alpine & at treeline.Various surfaces buried in early January including a rain crust, spotty surface hoar and preserved stellar snow crystals are now about 100-130cm deep and may provide a sliding layer for future avalanches. A surface hoar layer buried in mid-December is gaining strength, but professionals are still treating it with caution as the consequences of an avalanche on this layer would be high. Occasional hard, planar results have been reported on this layer in snowpack tests. It's now down about 175cm in the snowpack.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.