Purcells

The cooling has started, but there may be one more day with significant daytime heating.

Fair - Timing or intensity of solar radiation is uncertain on Thursday

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 in the afternoon.

A couple of remotely triggered avalanches up to size 2.5 were triggered on Tuesday in the alpine on Northeast ( mid-January persistent weak layer) and West ( mid-December deep persistent weak layer). There was also a natural size 3.5 avalanche on an East aspect that was estimated to be about 200 cm deep and may also have been the mid-December layer.

I suspect that freezing levels rose as high as 3000m during the recent warm spell and that rain may have saturated the upper snowpack. At higher elevations the surface is heavily wind affected. A breakable crust already exists in the alpine and as the freezing level continue to drop a widespread melt freeze crust will form on all aspects and elevations. The depth of the mid-January surface hoar is highly variable across the region and it may have been destroyed by the warm snow at lower elevations. Where it does exist it can be found between 20 and 50 cm below the surface. The mid-December surface hoar layer lies below a strong mid-pack down 60 to 120cm. The mid-November weak layer of crusts and facets can still be found near the bottom of the snowpack. It has been unreactive lately.