Widespread wind slab exists in the Alpine. This is still possible to trigger in unsupported terrain features. Avalanche hazard will increase with incoming snow Sunday.
Weather Forecast
A weak ridge of high pressure will move over Rogers Pass bringing dry, cool conditions and a mix of sun and cloud. Ridgetop wind will be Westerly in the 20-35 range and the alpine high will be around -14 deg C. A low approaching from the NW will bring precip that starts tonight and ends Sunday afternoon, 10-20cms are forecast by Sunday evening.
Snowpack Summary
Cold temps promoting facetting of the upper snowpack. Previous strong northerly and recent moderate southerly winds have added to the growth of cornices. Windslab can be expected in the alpine and exposed areas into treeline. On solar aspects, a crust is buried 40cm. Persistent weak layers from January and December are now buried 150-200cm.
Avalanche Summary
No new natural avalanches observed in the past few days. Several artillery controlled slab avalanches to size 2.0 on Thursday during a target verification shoot. Skier controlled size 2.5 wind slab on Mt. Sifton several days ago. Several cornice failures earlier this week up to size 2.5.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.