A series of storms are forecasted to hit the area beginning Dec. 31 in the early the following week.
The storm on Saturday into Sunday morning will be the most significant, with a low-pressure system developing and crossing the central and south Island. This weather pattern typically has some higher seasonal freezing levels and localized heavy rainfall. The freezing levels and how they may fluctuate throughout these storms will be important for downstream water flows such as the Browns and Tsolum rivers that flow into the Puntledge River.
The Comox Lake reservoir is currently at about 133.6 metres, or in the middle range, and is well-positioned for the storm activity.
With the significant storms forecasted, and to have flood risk management flexibility, the water discharge from Comox Dam increases starting the night of Dec. 31 from about 40 cubic metres per second (m3/s) to about 60 m3/s, and then up to about 110 m3/s as the storms hit the watershed. The high river flow rate may be in place through Friday, Jan. 8. River flows will also be going up and down, especially over the weekend, as BC Hydro adjusts operations in coordination with the high ocean tides, known as “king tides.”
BC Hydro is providing a public safety advisory to stay away from the Puntledge River through Jan. 8. Temporary danger signage will be placed along the river as of Dec. 31.
Water inflows into the reservoir on Saturday and Sunday morning may have an hourly peak of about 200 m3/s. Downstream releases from the dam may range from about 110 m3/s down to about 30 m3/s or so during the high ocean tides.
This is another period of some of the highest ocean tides of the year on Saturday through Monday. The storm hitting Saturday is forecasted to have southeast winds and a low-pressure centre crossing the Island, which may cause some storm surge up the estuary. The surge may peak near the Sunday morning high tide. BC Hydro will be closely watching how the Browns and Tsolum rivers may react to the Saturday-Sunday storm.
If there is a change in the weather forecast, BC Hydro may adjust operations, and if there is a significant change, it will issue another community update. Like all weather forecasts, there can be significant changes as systems track toward the West Coast and evolve.