VANCOUVER - Rainfall, wind, snow and winter storm warnings have been lifted for all of southern B.C. after a powerful system swept across the province leaving flooded or snow-clogged roads in its wake.

On Vancouver Island, torrential downpours forced flood watches or high streamflow advisories for several waterways and the deluge also prompted a boil water advisory for all users of the Comox Valley water system, including residents of Courtenay and Comox.

The Comox Valley Regional District says in a news release that severe rainfall has caused turbidity levels at a back-up pump station to rise above acceptable thresholds, triggering the need for the boil water notice.

Environment Canada says the two-day storm dropped as much as 100 millimetres of rain on Port Alberni and parts of eastern Vancouver Island, equivalent to an entire month of rainfall, while more than 50 millimetres fell Thursday at Vancouver International Airport.

In the mountains, Avalanche Canada says heavy snow has created a “high” possibility of slides on south coast and Vancouver Island mountains, as well as through most of east-central and southeastern B.C., meaning very dangerous avalanche conditions exist.

An “extreme” avalanche ranking, which means natural and human-triggered avalanches are certain, remains posted for some regions along the Alberta/B.C. boundary throughout Jasper National Park and in the alpine and treeline regions of Banff, Yoho and Kootenay national parks.