Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
South Rockies.
Confidence
Fair - Due to variable snopack conditions
Weather Forecast
Yesterday's ridge of high pressure slides to the south as a weak system approaches from the west. No precipitation is expected and winds remain light out of the W, NW. Expect a daytime high of -6 with an overnight low of -13 under mostly sunny skies. A system tracks just south of the area Wednesday night into Thursday bringing scattered flurries to the region. The tracking is pretty sketchy at this point, but I think we'll get at least 2-5cm of snow, maybe a few more if the system moves a bit further north. Stay tuned for more details.
Avalanche Summary
There were numerous avalanches both natural and human triggered from Size 2 - 3 in the adjacent forecast areas last week where avalanches failed near the ground on the crust/facet combo. If you have any observations from the field, please drop us an email: [email protected].
Snowpack Summary
5 -10 cm of snow fell Sunday (111211) under light winds. Going forward, things are going to get interesting as this new snow fell on surface hoar (SH) crystals that average 10mm in size. This is almost the perfect recipe for a SH problem as most of the SH is likely well preserved under the new snow. This is a minor issue for the short term, but, this could be a significant player in the long term. If you're headed out into the field, I'd love to hear where you're seeing the surface hoar. I'd also be psyched to know if it's standing up or lying down. Thanks in advance for the observations.Upper elevation snow depths average a meter. Photos from the field show that the alpine is just barely open to travel in most places. The mountains look good from afar, but it's far from good above treeline where the snowpack is still pretty thin.It's been almost two weeks since our last significant storm and since that time the snowpack has suffered an unrelenting barrage of wind from around the compass rose leaving the snow wind damaged throughout most of the region. The saving grace for ski quality has been the cold temperatures which have faceted the upper 20 cm of the snowpack making for fun & fast skiing.The Rockies are home to a nasty raincrust /facet combo near the ground. This is the classic house of cards setup that professionals throughout the region are concerned about. With numerous recent avalanches failing in this layer in the Rockies recently the chance of a large full depth avalanche remains a concern. Triggering an avalanche in this weak layer will result in a large & destructive avalanche that will likely be unsurvivable.Stay conservative in your terrain selection and give the steep rocky slopes a miss, as these are the kinds of slopes where the weaknesses near the ground could still be triggered by the weight of a skier or sledder.
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.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.