Heavy rain expected Friday in southern Quebec

While the storms missed Montreal on Wednesday, heavy rain fell along the northeast shoreline of Lake Ontario. The region around Kingston, Ontario was hit hard, with flash flooding reported. Between 25 and 90mm of rain fell across the region in just a few hours. (Global TV)

Many parts of southern Ontario, western New York and the northeast US have had a very wet summer. Wednesday was no different, as a cold front cut across the region, tapping into deep tropical moisture. The storms on Wednesday missed Montreal, but impacted the Kingston, Ontario region with flash flooding. Some neighbourhoods around Kingston reported 60 to 90mm of rain in a very short time. Numerous business and roads were flooded.

Further south in Pennsylvania and across the Mid-Atlantic US, the rain and storms have been relentless all summer. Streams and rivers are running very high, and serious flooding has already occurred, especially in Pennsylvania and New Jersey. In Wilkes-Barre and Scranton, over 100mm (4 inches) of rain fell on Monday alone. It was the most rain in a 24 hour period since Hurricane Connie in 1955. In the state capital of Harrisburg, 400mm (16") of rain fell during the month of July, the normal is 150mm (6 inches). At the same time, despite the oppressive humidity, parts of northeast New York, northern Vermont and Southern Quebec have been rather dry, with near drought conditions at times. Montreal has had close to 180mm (7 inches) of rain since June 1, but the majority of that has been very localized around Trudeau Airport, and occurred on just a few days. Rainfall to date in August is 33.6mm, the monthly 30-year average for the city is 94.1mm. On L'Ile Perrot, I have recorded 61mm since August 1, thanks to a few well placed thunderstorms.

Heavy rain and thunderstorms are forecast in Montreal on Friday. At this time forecasters are expecting 20 to 30mm rain.

Heavy Rain for southern Quebec
We will add to that monthly total on Friday, as low pressure over the Great Lakes combines with and advancing cold front to draw deep moisture northward from the Gulf of Mexico. The day will be very humid and unsettled, with heavy downpours and embedded thunderstorms likely. The showers will begin overnight in the Ottawa Valley and in the early morning hours in Montreal. The biggest threat for heavy rain in the St. Lawrence Valley will be in the afternoon. Rainfall accumulations could exceed 25mm (1 inch) in several locations. The storms should be fast moving, which should limit the risk of any flash flooding in metro Montreal. Skies should clear out early Saturday, setting the stage for a decent weekend, with just a slight risk of an isolated shower. Mostly sunny skies are forecast, with daytime high temperatures between 24 and 27C (75-80F).