Okanagan residents are being urged to prepare for further flooding Thursday when heavy rainfall is expected to return to the area.

Brian Reardon, the Central Okanagan Region District's director of emergency operations, is expecting water levels to peak Thursday evening or Friday morning.

"What we are expecting to see is unprecedented water levels as a result of rain, rising temperatures and melting snow pack," Reardon said, adding that the ground in the region is already saturated.

"If you haven't started preparing, now is the time."

Kelowna Floods 2017

Axel Roscovich, 11, working hard Thursday to fill sandbags for his neighbourhood. (Tina LovGreen/CBC)

Last week a 'dress rehearsal'

Reardon said residents who saw flooding last week should expect to see further flooding in the days to come, and those in low-lying areas who didn't see flooding should prepare for it now.

He said last week's flooding may prove to have been "just a dress rehearsal" for this week.

Reardon said sand and sandbags are available at numerous sites around the region. More detailed information is available on the regional district's website.

Reardon also advised residents to move possessions to upper floors, make plans for family pets, and have a "grab-bag" ready to go at a moment's notice if evacuation becomes necessary.

Kelowna Floods 2017

Truck carrying newly filled sandbags drives into the Holiday Park resort near Vernon Creek. (Manjula Dufresne/CBC)

Todd Cashin, with the City of Kelowna, said city engineers have been analyzing maps and other data to try to determine where streams are likely to overflow their banks and how that will affect residences and infrastructure.

"Our cup is full. The bucket's full," Cashin said. "There's really nowhere more for the rain to go except up over creek banks and up onto people's properties along our lakes, so on the advanced planning side, that's really what we've been planning for."

BC Hydro says above-average reservoir levels in the Columbia Basin could require them to release some water and increase river flows, but, depending on rainfall and the speed of snow melt, this might not be necessary.

Special weather statements in effect

Environment Canada has posted special weather statements for a large area of south-central B.C., warning of incoming thunderstorms and heavy rain in a region already plagued by flooding and mudslides.

The Central Okanagan Regional District has issued another round of evacuation alerts covering nearly 600 properties at the south end of Wood Lake in Lake Country, just north of Kelowna.

Kelowna Floods 2017

Washed out logging road just northeast of St. Ives on Shuswap Lake. The blockade of this road is affecting Seymour Arm residents. (Sue Kyle)

Flooding and washouts are also causing problems in the Shuswap and around Kamloops and Merritt, and the search continues for two men missing and believed killed in separate incidents in Cache Creek and Tappen.

Environment Canada is forecasting scattered showers in the region Wednesday, with heavier rainfall and possible thunderstorms beginning Thursday.

With files from Brady Strachan and the Canadian Press.