Happy New Year! Warm air and sun may create some touchy pockets of wind slab in the short term. Avalanche danger trending down for the weekend.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Clear skies and light winds throughout the forecast period. Valley temperatures between -10 overnight and -5 during the day. Alpine temperatures between 0.0 and +5.0 on Friday, and around 0.0 or slightly below freezing on Saturday and Sunday.
Avalanche Summary
On Tuesday a size 1-1.5 skier-triggered wind slab avalanche was observed in Body Bag Bowl in the Spearhead Range. The rider went for a 30m ride and lost a pole, but did not sustain any injuries. On the same day, a size 1.5 slab avalanche was triggered on Rainbow Mountain. The avalanche, which occurred on a lower-elevation northeast facing slope, is thought to have failed on the mid-December surface hoar. On Wednesday, there was a report of a rider-triggered size 1 wind slab avalanche near Adit Lakes in the Fitzsimmons Range. The avalanche occurred on a northwest facing slope at 1950m. Small solar-induced loose wet avalanches have also been reported. The size and likelihood of loose wet avalanches will increase with warmer alpine temperatures expected during the forecast period.
Snowpack Summary
Last weekend, the region received 15-20cm of low-density snow. At higher elevations, generally moderate winds have redistributed these accumulations into soft wind slabs in exposed lee terrain. Due to continued cool temperatures, these wind slabs have likely required more time than usual to settle and gain strength. Solar radiation has also come into play, and depending on the time of day, steep solar aspects may be moist or refrozen. In the upper 70cm of the snowpack you may find a layer of weak surface hoar which was buried in mid-December. Reports indicate this layer is spotty in its distribution, but may be something to watch as the overlying slab gets deeper and gains cohesion through settlement, warming and wind pressing. The mid and lower snowpack are generally considered to be strong and well-settled.
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 Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.