Heavy Rain Warnings and Potential for Flooding (flood bulletin, September 21-26, 2021)
WATERSHED CONDITIONS STATEMENT – FLOOD OUTLOOK
Issued September 21, 2021 at 11:30 am; Valid until September 26, 2021
The Upper Thames River Conservation Authority (UTRCA) is drawing attention to Environment and Climate Change Canada’s rainfall warnings. A slow moving low pressure system arriving from the American midwest will bring significant rainfall Tuesday evening through Wednesday night. Rainfall amounts of 50 to 60 mm are expected by early Thursday morning with locally higher amounts in excess of 75 mm in areas that receive multiple thunderstorms. Other forecasts are calling for potentially much more total rainfall possible in association with multiple thunderstorms (~125mm).
Recent rainfall over the past two weeks has made the Thames River watershed more susceptible to runoff. However, if the lower forecasted rainfall amounts are received, we do not expect significant river flooding. There will likely be localized drainage issues and floodplain inundation of smaller watercourses in areas that experience thunderstorms.
The higher forecasted rainfall amounts appear likely to be localized with thunderstorms; however, if the higher rainfall amounts are received over a wide area, more serious river flooding may occur. River level peaks would be expected overnight Wednesday and into Thursday.
UTRCA water management staff will be closely monitoring conditions and will provide updates as needed. The UTRCA’s flood control reservoirs at Fanshawe, Wildwood, and Pittock Conservation Areas are at seasonal levels and will be operated to reduce any downstream flooding.
The public is reminded to exercise extreme caution and stay away from all watercourses, which may quickly become fast-moving and higher than normal. Parents are encouraged to keep their children and pets away from all creeks, rivers and water bodies.