Avalanche Forecast

Moderate

Cool dry conditions are expected through the forecast period as an Artic High invades the interior. Friday may see isolated flurries with Nelson expected to receive around 2-5cm. Saturday and Sunday will be mainly dry. Winds will be light from the North on Friday, becoming more westerly on Saturday and Sunday. Freezing levels should return to near valley bottom with a possible weak inversion developing over the weekend.

Small natural, skier controlled, avalanches have been reported from steep open features at treeline.  There was also a report of a size 2 skier remotely triggered wind slab on a steep north aspect in the alpine near Nelson on Thursday.

Up to 30cm of new snow has fallen in the last week. Warm temperatures and southerly winds encouraged the formation of soft slabs at, and bellow treeline, and in wind loaded features. The new snow is resting on a widespread layer of surface hoar. These weak crystals sit above a melt-freeze crust on solar aspects, old wind slabs in exposed higher elevation terrain and loose facets in sheltered areas. Recent snowpack test from upper elevations south of Nelson produced only resistant failures on this layer. Other reports indicate that the interface is reactive to ski cutting at least at treeline and bellow. Between 40 and 60 cm below the surface, the mid-December interface can be found which consists of surface hoar or a sun crust. The early December rain crust can be found about 20 cm below that, up to an elevation of 1400m. Both of these layers are thought to be gaining strength. The snowpack below these layers is generally strong and well-settled.