‘Significant rainfall,’ freezing in some areas, expected in southern Ontario this week following weekend ice storm

A woman shields herself from rain under an umbrella while walking her dog along Toronto Lakeshore on Saturday, May 14, 2011. (Darren Calabrese / THE CANADIAN PRESS)

‘Significant rainfall’ is expected to hit much of southern Ontario in the coming days as central and eastern parts of the province recover from a major weekend ice storm, says the national weather agency.

By mid-week, the region could see between 30 and 55 millimetres of rain, which Environment Canada said will be at times heavy.

There may also be some local thunderstorms, it indicated in a special weather statement, which was issued late Monday afternoon for Toronto, Brantford - County of Brant, Burlington – Oakville, City of Hamilton, Dunnville - Caledonia – Haldimand, Mississauga – Brampton, Niagara Falls - Welland - Southern Niagara Region, Simcoe - Delhi – Norfolk, and St. Catharines - Grimsby - Northern Niagara Region.

The rainfall is expected to begin on Wednesday morning over southwestern Ontario before reaching the Golden Horseshoe by the afternoon. The precipitation is expected to last until Thursday morning.

Some parts of the province, notably regions in southwestern Ontario, could see more than 50 millimetres of rainfall, if thunderstorms occur, Environment Canada added.

The rain, which could result in the issuance of some rainfall warnings, may cause some localized flooding, especially in low-lying areas. People are being advised to contact their local conservation authority or the Ministry of Natural Resources if they have concerns.

Freezing rain expected in some regions, says Environment Canada

Some regions are forecasted to see periods of freezing rain with ice accretion of 2 to 5 millimetres on some surfaces. Snow and ice pellets are also possible in central and eastern parts of the province.

Environment Canada says this system could cause highways, roads, walkways, and parking lots to become icy, slippery, and hazardous, and may result in broken tree branches as the ice builds up and the wind picks up.

The 20 to 40 millimetres of rainfall that is expected to begin on Wednesday morning and last until Thursday morning, will be heavy at times. Local thunderstorms will cause higher amounts of rain to fall in some areas, the weather agency said.

The freezing rain will transition to rain as the temperatures rise. Localized flooding in low-lying areas is also possible, it said.

The affected areas include Caledon, Guelph - Erin - Southern Wellington County, Halton Hills – Milton, Pickering - Oshawa - Southern Durham Region, Vaughan - Richmond Hill – Markham, Newmarket - Georgina - Northern York Region, and Orangeville - Grand Valley - Southern Dufferin County.

Ice storm continues to impact several parts of the GTHA

Special weather statements have also been issued for Newmarket - Georgina - Northern York Region and Orangeville - Grand Valley - Southern Dufferin County, where gusty northwesterly winds could continue to cause impacts from the ice storm.

“Although temperatures have risen above freezing and the ice may have melted in some areas, strong wind gusts may result in further impacts,” Environment Canada warned.

Late-week warmup forecasted

These weather statements come as southern Ontario is poised to see a significant warmup.

CP24 metrologist Bill Coulter says that the temperature in Toronto is expected to reach a high of 18 C on Thursday and could even “flirt with 20 C.”

Thursday will be the warmest day of the week, with daytime highs set to dip down to around 10 C for the weekend.

And while Tuesday’s forecasted high is 4 C with sunshine, more freezing rain or ice pellets are possible throughout Wednesday, with a high of 3 C, Coulter said.

The weekend will see more moderate highs of 11 C, 9 C, and 10 C from Friday to Sunday, respectively.

Friday will have “variable skies” according to Coulter, meanwhile Saturday will be mainly cloudy with a light breeze. Sunday is expected to wrap up with afternoon clouds and a moderate breeze.