The BC River Forecast Centre has upgraded a high streamflow advisory to a flood watch on Mission Creek.

Heavy rain fell late Sunday and into Monday morning in the Kelowna area, pushing up levels on the creek.

Flows on Mission Creek near East Kelowna increased rapidly overnight, with current flows at 56m 3/s (approximately a 2-year flow). The water could rise another 80-100 m3/s today and into Tuesday, depending on the weather.

The river forecast centre says rainfall amounts in the 5 to 35 millimetre range were observed throughout the region since yesterday, and more is on the way.

A Severe Thunderstorm Watch was issued Monday Morning for the Okanagan, South Thompson, Nicola, Shuswap and Boundary.

Environment Canada says rainfall in some spots, including the Okanagan Valley, the Monte Creek area and Shuswap could see heavy rain exceeding 15 mm per hour. Strong wind, intense lighting and small hail are also possible.

An upper low is expected to track across southwest BC today, bringing wrap around precipitation with the potential for heavier rainfall and thunderstorms to the Southern Interior and Kootenays.

Levels on Okanagan Lake could start to creep back up after peaking late last month when Mission Creek and other waterways swelled due to rainfall and melting snowpack.

The upper low pressure system is forecast to move out of southern B.C. by tonight.

A high streamflow advisory remains in effect for the Similkameen River and tributaries, the Boundary including the Kettle River and Granby rivers, the West Kootenay including Slocan River and Duhamel Creek, and the East Kootenay including the Kootenay River and its tributaries.