Flood warnings issued in southern Ontario amid blast of warm weather and rain

Dec 30 2022, 12:11 am

The aftermath of a nasty Christmas storm is subsiding across southern Ontario, but it might be subsiding a bit too quickly, as a one-two-punch of warm temperatures and rain substantially increase the risk of flooding across the region.

Over 16 cm of snow has descended upon Toronto since mid-December, accompanied by frigid temperatures as low as the negative double digits that have so far prevented major melting.

But, as of Thursday, the mercury has soared into the high single digits and threatens to crack double digits by Friday. And the melt has already begun.

A system of precipitation is also moving towards the region, expected to arrive by the weekend, and the combined effects of the warm air temperatures and rain have Environment and Climate Change Canada warning of potential flooding in waterways across the region.

The government weather agency warns that “rapid snowmelt when the ground is still frozen can cause flooding even in areas that have not flooded before,” adding that “proper draining, even in winter, is important to reduce property damage.”

The coming band of rain could bring as much as 25 mm to the Greater Toronto Area, according to The Weather Network, while even higher rainfall totals of 30 to 44 mm are predicted for southwestern Ontario.

Melting snow and the approaching system have already combined to trigger flood watches in Niagara Region.

A flood alert was issued by the Niagara Peninsula Conservation Authority on Wednesday, while a region-wide alert followed on Thursday from The Weather Network, cautioning of localized flooding in waterways as mild temperatures, rainfall, and ice jams join forces.

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