Flood, wind warnings issued as heavy rain, ice, and runoff threaten region

London and area is expected a lot of rain over the next few days. Here's Eleanor Heagy with the UTRCA.

Environment Canada (EC) and local conservation authorities are urging residents across southwestern Ontario to prepare for significant rainfall, strong winds, and a heightened risk of flooding as an unstable low-pressure system moves into the region.

Rain, heavy at times, is expected to begin Sunday morning and continue through the evening and overnight, with total rainfall amounts of 30 to 60 millimetres and locally higher totals possible. Some forecasts suggest rainfall could reach as much as 75 millimetres in isolated areas. Precipitation may start briefly as freezing rain before changing to rain, with little ice accretion expected.

After the ice storm on Saturday, EC says the frozen or near-frozen ground conditions will limit the ability of soil to absorb the rainfall, increasing the risk of rapid runoff, localized flooding and ponding in low-lying areas. Some roads could become impassable.

Environment Canada is also warning of strong winds on Monday, with southwesterly gusts of 70 to 80 km/h expected as a strong cold front passes through. Winds are forecast to ease Monday evening as they shift to the northwest. Areas that receive freezing rain will be more vulnerable to damage, with the risk of utility outages and damage to roofs, fences and tree branches.

The Upper Thames River Conservation Authority has issued a flood watch and says recent freezing rain and existing snowpack have added to already saturated conditions across the watershed. About 10 millimetres of freezing rain fell on Dec. 26, adding to approximately 50 millimetres of snow water equivalent still present in parts of the basin.

With rain expected to transition to snow Monday as temperatures drop, officials warn that rapid runoff could lead to flooding in low-lying and flood-prone areas, with the potential for less frequently flooded areas to be impacted if higher rainfall totals materialize.

Flood control reservoirs at Fanshawe, Wildwood, and Pittock conservation areas will be operated to reduce downstream flooding.

The Kettle Creek Conservation Authority has issued a Watershed Conditions Statement — Flood Outlook, along with a Lake Erie Shoreline Conditions Statement — Flood Outlook.

Officials say heavy rain combined with snowmelt could cause creeks and streams to reach or exceed their banks, leading to localized flooding, particularly in areas with poor drainage.

“Elevated runoff and saturated ground conditions may result in increased water levels and flows in local creeks and streams,” said Jennifer Dow, water resources supervisor with the authority.

Along the Lake Erie shoreline, strong southwest winds of 50 to 65 km/h, with gusts of up to 100 km/h, could trigger storm surge, shoreline erosion, and localized flooding, particularly in Port Stanley.

Officials warn that ice-free conditions on the lake increase the risk of wave damage and flood uprush in low-lying shoreline areas.

Residents are urged to clear storm drains of snow and ice, secure loose objects, avoid flooded roadways, and stay away from rivers, creeks, and culverts.

Authorities also advise moving valuables to higher levels of homes where possible and keeping children and pets away from watercourses and frozen water bodies.

Environment Canada and conservation authorities stress the importance of continuing to monitor watches, warnings, and forecasts as conditions may change.

The flood outlook statements are expected to remain in effect until noon on Tuesday.