Forecast Updated Monday Dec 18 at 0900. Up to 40 cm of snow overnight has increased Danger Ratings. There's a dense slab reported at higher elevations.
Confidence
Low - Timing, track, or intensity of incoming weather system is uncertain on Tuesday
Weather Forecast
Zonal flow should be firmly established by Monday morning. Two pulses established within this flow are expected to deliver modest quantities of snow and wind to the Lizard and Flathead ranges through Tuesday evening. The models currently show 5 to 10cm for each 12 hour period between Monday morning and Tuesday night, but there is potential to double these amounts on Tuesday. Stay tuned for more details. UPDATE MONDAY MORNING: 40 cm of snow arrived overnight in the Lizard Range, triple the amount originally forecast.MONDAY: Overcast, freezing level starting at 600m rising to 1000m in the afternoon, moderate to strong southwest wind, 2 to 10cm of snow possible.TUESDAY: Overcast, freezing level near valley bottom, light variable wind at valley bottom, potentially strong southwest wind at ridge top, 5 to 20cm of snow possible.WEDNESDAY: Overcast with some clearing in the afternoon, freezing level at valley bottom, light variable wind, 1 to 5cm of snow possible.
Avalanche Summary
Monday Morning UPDATE: Explosive triggered avalanches to size 2.5 No new avalanches observed on Sunday. On Friday and Saturday small sluffs and soft slab avalanches were reported to size 1.Please submit your observations to the Mountain Information Network.
Snowpack Summary
The region was hit hard by wind over the weekend, but there may be protected areas where up to 10cm of new low density snow survived. At or just below the surface there is a wide range of conditions. Windward slopes have been scoured down to the old rain crust and/or rock. Sun and temperatures crusts have formed on south through west facing slopes. In sheltered terrain at and below treeline, large feathery surface hoar and sugary facets exist. Roughly 30 to 60cm below the surface you should be able to find a hard crust that was buried near the end of November. This crust is approximately 30cm thick and extends from 1600m to mountain top on all aspects. Below this crust, the snowpack is moist to ground. Average snowpack depths at treeline in the region range from 70 to 110cm.
Problems
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.