January 30, 2004 South Columbia Region Weather: Snowfall amounts have been substantial over the past 4 days with storm snow accumulations of 50-80 cm in the Purcells , and 70-100 cm in the Selkirks. Temperatures rose through Friday afternoon and winds were light. Friday afternoon should bring an end to the major snowfall, with lingering flurries through Saturday morning. The change in weather Friday will bring a blast of wind and temperatures dropping 10 degrees in the alpine as a cold front passes through. Above treeline, winds will peak at 50-70 km/h from the S or SW before dropping to moderate strength from the NW. Temperatures will be seasonable and steady until Monday. Snowpack: Snowpack observations show denser snow overlying soft snow near the surface. The Purcells have seen more wind than the Selkirks, enhancing this condition. Weaknesses are reported within the storm snow 20-30 cm and 30-60 cm below the surface. Below the copious storm snow there is concern about a buried layer of surface hoar that is 40-80 cm below the surface. This layer is more prominent as you move south. On south aspects the surface hoar lies on a crust, a combination known to be particularly weak. Avalanche Activity: Avalanches were reported Thursday and Friday from several locations. Poor visibility hampered observations at higher elevations. In the Purcells, where visibility was best, large natural avalanches were observed on Friday; some of these ran on the surface hoar layer. Forecast of Avalanche Danger Up To Monday Evening (February 2, 2004) Alpine - HIGH, improving to *CONSIDERABLE on Sunday Treeline - HIGH, improving to *CONSIDERABLE on Sunday Below Treeline - CONSIDERABLE improving to *MODERATE on Sunday Travel Advisory: Winds on Friday will enhance slab conditions further, creating windslabs that will be ripe for skier triggering Saturday. *As danger moderates through the weekend under stable weather, users should be aware that it is most likely for deadly avalanches to occur while danger is rated as CONSIDERABLE. Kootenay Boundary Region Weather: A pacific system continued to affect the region on Friday, bringing more snow, warmer temperatures and moderate SW winds. Moderate to heavy fairly wet snow on Friday should ease off to flurries later in the day as a cold front passes through. Passage of the front will be accompanied by strong SW winds. Temperatures will drop below zero at all elevations by Friday. NW flow will bring dryer and colder conditions for the weekend through to Monday, with some lingering flurries on Saturday. Snowpack: Slabs have formed in the alpine and at treeline; the snowpack has reached a critical state, with 60-120 cm of snow in the past week overloading a weak layer of surface hoar. On southerly aspects, this surface hoar layer sits on a crust and is now deep enough to produce very large avalanches. Strong winds Friday night will continue building windslabs mostly on north and east facing slopes. The middle and lower snowpack is well settled, and deserves less attention right now than the upper weaknesses in the snowpack. Avalanche Activity: Recent activity includes numerous large, destructive natural avalanches as well as avalanches triggered by explosives, including one very large Size 4 avalanche. One important observation was of activity on southerly aspects between 1600 and 1800 m, which likely indicates the presence of a buried crust. Forecast of Avalanche Danger Up To Monday Evening (February 2, 2004) Alpine - HIGH, improving to CONSIDERABLE on Sunday Treeline - HIGH, improving to CONSIDERABLE on Sunday Below Treeline - CONSIDERABLE Travel Advisory: Snowfall will subside and the avalanche danger will improve slowly. Natural avalanche activity will decrease, but the likelihood of triggering an avalanche will remain. You should wait until the snowpack improves before entering steep slopes or terrain that is threatened by avalanches from above.