Warm weather mixed with snowmelt at higher elevations will cause Okanagan Lake to rise this week.

That melt is delayed by a week this year, due to cooler conditions so far this spring.

Shaun Reimer, section head of Public Safety and Protection for the Thompson Okanagan region, says that's not a bad thing.

“The later the onset of freshet, the better it is to create storage in the lake,” he said. “(But) it becomes more problematic for tributaries because we don’t want the mid- and high-elevation snowmelt to occur at once.”

He said it's better to have lower- and mid-elevation snow melt first.

“Late in May and June (is preferable) for the higher elevation for the snow to come down,” he said. 

Currently, Okanagan Lake is 106 centimetres below full pool, which is 61 cm lower today than it was this time last year.

“We are currently discharging about a centimetre and half of water on the lake per day, so that based on the April to July forecast of the amount of water expected to come in, it should be managable.”

That doesn't take into account wet weather in the valley bottom or if the water comes down very quickly, like last year. “That can become very problematic,” he said.

At the upper end of the valley's lake system, Reimer says Kalamalka Lake will be able to absorb that kind of melt without issue.

“Right now, we are actually 24 to 25 cm lower for that lake level than we were for the same day last year,” he said.

The outflow through Vernon creek is flowing at maximum capacity.

“There are some issues with that outflow in that we have had the dam gates wide open since early January, and unfortunately the outflow does not rise until the lake level rises,” said Reimer.

He says the lake will come up quite quickly, and outflows will have to come up as well to between four and six cubic metres per second.

Weather across the Okanagan is expected to be warm and sunny this week, followed by rain on Saturday.