UPDATE 1:10 p.m Environment Canada says the main threat from the current weather system coming through the Southern Interior Sunday is severe thunderstorms. “We have what is called an upper low. It’s like a low pressure system, but high and it’s kind of hanging around the Washington coast at this point. And it’s like you’re being fed moisture from the southwest,” explains meteorologist Ken Dosanjh. “So we basically have widespread rainfall across southern B.C. at this point”. Dosanjh says the concern isn’t so much high winds or hail, but heavy rainfall. “At the moment, everywhere is quite sensitive to high river levels at this point. So just adding more rainfall, especially with integrated storms where there’s heavy rainfall right now, can lead to some concerns for the waterways,” Dosanjh said. As a result of the weather system, the River Forecast Center issued a high flow advisory for the area Sunday morning. The upper low should begin to move out of the area Monday night. Photo: Environment Canada Environment Canada’s storm outlook for BC indicates a high risk for parts of the Thompson-Okanagan ORIGINAL 10:20 am Environment Canada has issued a severe storm warning for parts of the Southern Interior, including the Thompson-Okanagan, prompting the BC River Forecast Center to issue a high flow warning for the region. The severe thunderstorm watch issued Sunday morning covers the entire Okanagan Valley as well as South Thompson, Shuswap, Nicola, Boundary and Fraser Canyon. Severe thunderstorm watches are issued when atmospheric conditions are favorable for the development of thunderstorms that could produce one or more of the following: large hail, damaging winds, or torrential rainfall. Environment Canada says heavy rainfall is likely to cause flooding and pooling of water on roads. The Environment Canada Thunderstorms Outlook for BC shows the Okanagan, Shuswap and South Thompson regions at high risk. Some areas may see 15 to 25 millimeters of rain over the next couple of days, which is cause for concern. The BC River Forecast Center issued a high flow advisory for the Southern Interior at 9:30 a.m. Sunday. It covers the Okanagan, including Mission Creek and tributaries, the Similkameen River and tributaries, the Kettle and Granby Rivers in the Boundary Region, and the West and East Kootenay watersheds of the Kootenay and Slocan Rivers and Duhamel Creek. The river forecast center says unsettled weather over the next two days will bring rain, with the possibility of heavier rainfall in some areas, and river responses are expected to be highly variable. Hydrologic modeling indicates the potential for moderate flows in the 2-year to 5-year return range in some areas. However, given the uncertainty of where the heaviest rainfall could occur, it is likely that small and medium watersheds will experience high flows on Monday and Tuesday.
