Montreal to settle into a warm and humid weather pattern

A very familiar look to the sky over Montreal this summer as the sun plays with developing cumulus clouds and thunderstorms. Montreal remains on the northern edge of a warm and humid airmass that has been delivering rounds of heat and humidity followed by strong thunderstorms. This cycle is expected to persist for the foreseeable future. (Valley Weather)

Large parts of eastern North America seem to be in a rinse and repeat cycle of warm and humid conditions, along with occasional showers and thunderstorms. This is quite typical weather for July, but what is making it different this year are the intense rain producing thunderstorms that have resulted in flash flooding in many locations.

Montreal has been fortunate to date, as most of the big wet thunderstorms have skipped the city centre. On Monday afternoon, a decent storm dumped close to 15mm on the region, producing ponding of water on highways, but little else. Trudeau Airport has measured a manageable 26mm of rain so far this month.

The balance of this week will be warm and muggy, with scattered showers and thunderstorms almost daily. High temperatures will range form the upper 20s to near 30C (80-85F), while overnight lows will be around 20C (68F). This weather pattern will continue well into next week. 

The sudden and heavy downpours make many Montrealers nervous after the deluge that flooded parts of the city last summer from Tropical Storms Beryl and Debby. The horrific images from Texas have added to the nervous emotions that exist whenever we have thunderstorms.

Most of the flash flooding we have in Montreal is caused by the inability for our sewers to handle sudden storm flows. This is very different from the circumstances that impacted the Texas Hill Country on July 4. That region has topography that is very prone to significant flash flooding, with narrow rivers channels and hilly ground. 

Efforts continue to locate victims of the horrific flash flooding that occurred in Kerr County, Texas on Friday, July 4. The death toll stands at 119 as of Wednesday morning, with 173 still missing. (Photo: Sergio Flores)

The Texas flooding is beyond catastrophic. The death toll has risen to 119 as of Wednesday morning, with another 173 missing. Intensive search, rescue and recovery efforts continue in searing heat and humidity. On July 4, between 250 and 500mm of rain fell in just a few hours, causing the Guadeloupe River to rise from a few feet to a surging 26 feet (8 metres) in less than an hour. The massive flash flood swept away homes, cottages and campers across Kerr County. The death toll includes at least 36 children.

Widespread heavy and slow moving thunderstorms have been producing flooding over many parts of the US. Major flash flooding has been observed in Texas, New Mexico, Illinois and North Carolina over the last 48 hours. Some of those wet and windy storms have crept into southwestern Ontario.

Be weather aware. As we approach the one year anniversary of the Montreal flooding, it is important to listen to daily forecasts, and especially watches or warnings that may be issued for heavy rainfall or thunderstorms. Numerous apps are available that push out weather information and warnings, including those from Environment Canada and The Weather Network.

One thing this summer is delivering across southern Quebec is plenty of heat and humidity. These weather conditions continue to fuel frequent moisture laden storms. I see no change in this pattern any time soon. Stay safe.