Some small wind slabs to watch for in the alpine. The upper snowpack is slowly becoming more supportive and allowing for better travel, however, the lower snowpack remains weak and unsupported. Conservative terrain choices are still a good idea.
Strong to extreme winds on Sunday night formed small wind slabs in immediate lee areas of the alpine. These are reactive to skier triggering in steep terrain.
The lower snowpack is comprised of weak facets and depth hoar with the upper snowpack forming a 40 to 90 cm thick slab above. This weak basal layer is uniform across most of the forecast region and has been responsible for most of the larger avalanche activity this season.
On a flight Sunday, Visitor Safety observed a recent size 2 cornice triggered slab on the East side of Copper mountain. Ski hills reported ski cutting some small wind slabs in lee areas near ridge crests on Monday, and were still able to trigger a couple of size 2's at 2300 m with explosives on Sunday that scrubbed down to the ground in areas that were previously uncontrolled.
Some small wind slabs in the alpine. At treeline 10-20 cm of recent snow sits over a spotty surface hoar/sun crust Jan 4 interface. The Dec 17 surface hoar/sun crust layer is down 25-50 cm, and generally not reactive. The Nov 16 deep persistent layer is down 40-90 cm and continues to produce sudden failures in snowpack tests. In areas west of the divide, these layers are generally deeper and more spread apart in the snowpack.
Tuesday will see some light flurries in the morning, becoming a mix of sun and cloud in the afternoon. Alpine winds will start in the moderate to strong range out of the W, and decrease as they switch to NW in the afternoon. Alpine temperatures will range from -10 to -15°C.
