Avalanche Forecast

Low - Timing, track, or intensity of incoming weather system is uncertain on Saturday

The provincial weather pattern features a clash of titans as juicy warm air streams into the northern interior and then smashes into a rather bullish Arctic front. The Cariboos and North Columbias are expected to see the most action from this engagement, strong snow and wind are expected through the weekend. We know that weather models do not capture these kinds of events well, there could be more snow and wind than forecast, and there is increased potential for very heavy snowfall locally. Take the following ranges as a suggestion, but do not bet the house on them.(FRIDAY: 10 to 30 cm, strong west wind)FRIDAY NIGHT: Freezing level around 1300 m, strong west/northwest wind, 15 to 40 cm of snow. SATURDAY: Overcast, clearing in the evening, freezing level at valley bottom, moderate to strong west/northwest wind, 10 to 20 cm of snow.SUNDAY: Overcast, freezing level at valley bottom, light to moderate west/southwest wind, 5 to 15 cm of snow possible.

On Thursday explosive control work produced avalanches to size 3.5 on a variety of aspects above 2100 m. Failure planes included mid-January, mid-December and late-November. Natural avalanches to size 2 were observed on east facing slopes near 1900 m. Wednesday included further observations of recent activity showing storm slabs releasing naturally, from size 2 to 3, on all aspects and elevations. South aspects were especially active where solar warming served as a trigger. Explosive control also yielded numerous persistent slab results from size 2 to 3.5 on all aspects/elevations. All our persistent weak layers of concern were active, with the possible exception of the early January layer. The mid-December layer is also suspected in two natural size 4 releases in and near the Glacier National Park area.On Tuesday, natural avalanche activity was widespread, running on all aspects and elevations. Storm and wind slabs reached size 3 while persistent slab avalanches failing on the mid-December layer ran to size 3.5. A size 2.5 avalanche on a northeast facing slope at 1920 m resulted in a single fatality. More details are available here.

20 to 50 cm of new snow fell Thursday and Friday. This rests on up to a meter of new snow that fell last week which has settled into a slab aided by a warming event on Monday the 29th and strong to extreme southerly winds on January 29th and 30th. Four active weak layers are now quite deep in our snowpack:1) 80 to 160 cm of storm snow sits on a crust and/or surface hoar layer from mid-January. The crust is reportedly widespread, with the possible exception of high elevation north aspects. The mid-January surface hoar is 5 to 20 mm in size and was reported at tree line elevations and possibly higher. 2) Deeper in the snowpack, the early-January persistent weak layer is 150 to 175 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is found at all elevation bands. 3) Another weak layer buried mid-December consisting of a facet/surface hoar/crust combination is buried up to 200 cm below the surface. It is most problematic at and below tree line. 4) A crust/facet layer from late November is yet another failure plane responsible for very large recent avalanches.