Purcells

Sunny skies and freezing levels as high as 3500 m are continued on Wednesday. As the snowpack deteriorates, natural avalanche activity is to be expected. Solar induced wet slabs may be large and run full path.

Fair - Timing or intensity of solar radiation is uncertain

The weather pattern will begin to change tonight as a dominating ridge of high pressure will start to break down. This will allow a strengthening, moist SW flow to enter the region. Wednesday: Freezing levels will continue to be near 3200 m, with sunny skies and light Southerly winds. Thursday: Light precipitation should begin later Wednesday night, while Thursday will bring moderate amounts. Freezing levels will fall 1500 m. Ridgetop winds will be light gusting moderate from the SW. Friday: Lingering, light precipitation in the morning. Freezing levels will rise to 2000 m, with possible sunny skies in the afternoon.

On Monday, numerous natural slab avalanches up to size 2 were reported. These occurred on solar aspects out of steep rocky terrain. On Sunday a natural cornice fall triggered a large size 3.5 avalanche. This occurred on a North aspect at 2800 m. The width of the avalanche was 100 m, running 1100 m in length. This ran on facets to ground. This may be an indicator of more to come; especially with an increase of solar radiation and high freezing levels. One other natural cornice fall triggered a size 1.5 on the slope below. This cornice chunk triggered the March 27th layer on an East aspect around 2700 m.

Mild temperatures and solar radiation have settled out much of the upper snowpack. Spring-like conditions prevail, with surface crusts on solar aspects and melt- freeze conditions on all aspects below 1700 m. Over the next day the region will see less of a re-freeze, and higher freezing levels promoting moist snow throughout. Up to 120 cm sits on the March 27th interface. This interface consists of a sun crust on southerly aspects and a temperature crust on more northerly slopes. A thin layer of facets and or surface hoar can be found on this crust on all aspects. Be aware of avalanches running on this layer over the next few days. There is also a weak layer of facets or depth hoar in shallower snowpack areas that is suspect once the region starts seeing warm days without overnight refreeze. Cornices are reported to be very large and exist on most ridge lines. These will become weak under the direct solar influence and warming. I would stay very clear of cornices from above and below. The mid-pack is well settled and strong.