Spring conditions with overnight freezing and daytime warming.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Thursday
Weather Forecast
The freezing level should drop to valley bottoms overnight, and then rise back up to about 1500 metres during the day. Expect continued sunny skies and light winds during the day on Thursday. We should see another good re-freeze to valley bottoms overnight and into Friday morning as the cooling continues. More sun and light winds on Friday. Saturday should be cooler with cloud and moderate Southwest winds developing in the morning, and light precipitation starting overnight.
Avalanche Summary
No new avalanches reported
Snowpack Summary
The cool down has started, with freezing levels dropping down to valley bottoms. We are in a spring like diurnal melt-freeze cycle that should cap the snowpack with a strong crust by the end of the forecast period. Record warm temperatures may have resulted in moist snow and an isothermal snowpack at lower elevations on Monday. High freezing levels (above mountain tops) have settled the near surface snow which overlies a rain crust to 1900m, facets, and/or surface hoar. The mid-December crust/facet layer is down 40-80cm. There is not much snow left below 1600 metres elevation due to the prolonged warm weather and spring like conditions.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.