Widespread heavy rain warnings posted for southern Quebec and Ontario

Tropical storm Debby made another landfall in South Carolina early Thursday morning. The storm center was located 100km west of Myrtle Beach, moving northwest at 11km/h. The remains of Debby will move into New York State on Friday, bringing heavy rain to Montreal. (Photo: Stephen B. Morton)

Heavy rain warning has been issued for southern Quebec and eastern Ontario including metro Montreal for 50-100mm of rain tonight through Saturday morning. Flood Watch for upstate New York including the St. Lawrence Valley.

The remains of tropical storm Debby will impact southern Quebec and Ontario starting Friday. A swath of deep tropical moisture will set up to the north and west of the track of Debby, interacting with a cold front pushing southeast across Ontario. Rain will begin late Thursday evening and persist through Friday. The rain will be heavy at times, along with embedded thunderstorms.

Forecast amounts are expected to be in the 50-100mm range (2-4 inches). Where the heaviest rain falls will be determined by the final track of Debby, expected to lift north from South Carolina towards Lake Champlain by Saturday morning.

The Canadian Hurricane Centre forecast track of tropical storm Debby from coastal South Carolina northeast across our region and into Atlantic Canada.

The various models have the heaviest rain falling along the St. Lawrence Valley, but scenarios range from right along the International Border to locations far northwest of Montreal across the lower Laurentians and Ottawa Valley.

The expected accumulations of rain are cable of producing local flash flooding, similar to what we experienced during Hurricane Beryl in July. Aside from the heavy rain, we can expect gusty winds, up to 50km/h along with very muggy conditions in the tropical airmass.

Conditions should improve on Saturday, but the airmass will remain unstable, with a risk of scattered showers into Sunday.

Debby made landfall along the Florida Gulf Coast on Monday as a category 1 hurricane. The storm was located 100km west northwest of Myrtle beach early Thursday morning. Debby has weakened to a tropical storm, with 75km/h winds. The storm will move slowly inland today, before increasing in forward speed towards the northeast this evening and Friday. Debby is already responsible for hundreds of millions of dollars in damages as well as six fatalities across the southeastern US.