Confidence
Poor - Timing, track, or intensity of incoming weather is uncertain on Sunday
Weather Forecast
For better or worse, weather models are far from perfect. They have a particularly tough time with situations like the one we're in now. The models call for rapidly changing freezing levels, strong to extreme winds out of the SW and uncertain precip amounts. My best guess for the South Columbias is 30 cm of snow. The big winds will likely get right to work Saturday night out of the SW with sustained strong values, gusting extreme. Freezing levels will spike Sunday and may rise as high as 1800m. Cooling will build in Monday and then Tuesday looks to be fairly dry. This is all fine & good, but I must admit that my confidence in any model is quite low for the short term, so, take this weather forecast with a grain of salt and be ready for rapidly changing conditions.
Avalanche Summary
Very little significant avalanche activity was reported from the region Friday.
Snowpack Summary
60 - 100 cm of storm snow has fallen in the last week which has settled out nicely in the region. A few stubborn windslabs were observed on Friday, but these were largely unreactive to provocation.Going a little deeper in the snowpack we find that the snowfall from the past week rests on dry cold snow formed during an Arctic Outbreak. A Rutschblock test in the north showed a result of RB6, MB down 90 on this layer. In the south a CTE test produced a failure down 70 at this interface. We may see some limited activity out of this layer Sunday, but I think that will be its last kick at the can.Below this lies the January 13th SH/FC layer that is spotty in distribution, but it is still capable of performing. Deep in the pack the mid December layer has gained a lot of strength, but it may still be an issue in areas of thin shallow 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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.