The BC River Forecast Centre is warning of a heightened concern of spring flooding in the Kamloops area.

It says the North Thompson snowpack is currently sitting at 128 per cent of normal, up from 119 per cent as of April 1 – the highest it has been since 1999.

“Flood risk has increased considerably due to colder April temperatures across the province and delayed snowmelt,” the River Forecast Centre said, in a bulletin Tuesday morning. “Continued cool weather in May is increasing the risk for major flooding if a prolonged heat wave occurs later in the month or June.”

“Snow pack is only one factor related to freshet flood risk. Weather conditions from May through June determine the timing, magnitude, and rate of snowmelt, where heavy rainfall events can exacerbate snowmelt-driven flows. An extreme heat wave – like the heat dome in late June 2021 – could lead to significant provincial flooding if it occurred between mid-May to mid-June.”

The South Thompson snowpack is currently at 107 per cent, up slightly from the 101 per cent reported last month. However,  just like last month, the River Forecast Centre says there are just four sites reporting across the entire basin.

“Since the South Thompson borders the North Thompson and Upper Columbia (which have significantly higher snow basin indices), it is possible that the snow pack is slightly higher than the snow basin index suggests,” the River Forecast Centre added.

The City of Kamloops says it is preparing for the potential for a severe freshet this year. Part of that includes the addition to two large private dikes – one on McArthur Island and one at Riverside Park – in the hopes that it protect infrastructure to a one in 20-year flood level while reducing the need to use temporary flood protection measures during the spring freshet.

Increased risk of flooding this year due to 2021 wildfires and flooding

The River Forecast Centre is also warning of the risk of localized flooding due to last summer’s wildfire season.

“Areas that recently experienced severe wildfire are at greater risk for higher peak flows (e.g., Upper and Lower Nicola, Guichon Creek, Deadman River),” the report added. “The Deadman River is currently under a high streamflow advisory from combined snowmelt and heavy rainfall occurring in the first week of May.”

It also says the flooding in November last year has also made many rivers – including the Coldwater, Nicola, Tulameen, and Coquihalla rivers – more vulnerable to freshet high flows.

Fortunately, the May 1 snow pack in the Nicola, Similkameen and Lower Fraser is near normal,” the report said. “However, due to the significant erosion and possible changes in river channel morphology that occurred within many areas, rivers may be at increased vulnerability to flooding at lower levels than previous freshet seasons.”

:Flows during the freshet season tend be sustained for longer periods of time during snowmelt, which is different from the fall flooding season that is driven by shorter duration, intense rainfall events.”

An updated seasonal flood risk forecast is set to be released on May 20.

You’ll find the May 1 bulletin here.