Global News meteorologist Ross Hull said that the bullseye for the strongest storms will be over the northeastern U.S., with parts of New York state down to Kentucky in line for potentially damaging winds, hail, heavy downpours and isolated tornadoes.
He said Ontario and Quebec are on the “northern periphery of this disturbance.”
“Once again it looks like parts of eastern Ontario could see some strong storms Monday late afternoon to evening with the biggest threat being heavy rainfall,” Hull said in an email.
“There are Rainfall Warnings in place from Ottawa south towards Kingston and east to areas north of Montreal where some downpours could deliver more than 50 mm of rain in a relatively short amount of time which could lead to localized flooding.”
As the weather system moves east into the Maritimes, there will be the potential for heavy rain Tuesday night into early Wednesday, Hull said, and a special weather statement has been issued.
Environment Canada says rainfall could exceed 50 millimetres over the northern half of New Brunswick and be up to 50 millimetres in some parts of Nova Scotia.
Parts of Nova Scotia are still reeling from a torrential downpour that triggered floods July 22 and killed four people, while Halifax recently had storms and flooding this past Saturday.
In an online bulletin, the U.S. National Weather Service’s Weather Prediction Centre warned Monday of an increased threat of severe thunderstorms and flash flooding from Tennessee into much of the eastern U.S., as well as record heat from Texas to Florida, creating a higher risk of wildfires.
In addition, heavy rain and flash flooding is expected in the Pacific Northwest on Monday.
The thunderstorms in the east are due to a fairly strong storm system tracking eastward from the Great Lakes, with a cold front reaching the east coast by Monday night, according to the Weather Prediction Center, part of the U.S.’s National Oceanic and Atmospheric Administration.
“Numerous thunderstorms are expected ahead of the cold front today, some of which are expected to be severe, containing the potential for tornadoes, damaging straight line winds, large hail and flash flooding,” WPC said.
Tornado watches were posted across 10 states, from Tennessee to New York, but the National Weather Service says the area of greatest concern is the Washington-Baltimore area.
The FAA has issued ground stops to a number of U.S. east coast airports due to the storm, including New York City’s JFK International Airport.
Thousands of federal employees in Washington, D.C., were sent home early from work Monday due to the storms, with all federal offices closing at 3 p.m.
The National Weather Service has issued a tornado warning for the greater D.C. area that will last until 9 p.m., as well as a flooding warning until Tuesday morning. A special statement warned that there may be “hurricane-force winds,” “strong tornadoes” and “large hail.”
U.S. President Joe Biden left on a four-day trip to Arizona, New Mexico and Utah 90 minutes early due to the weather
“This does look to be one of the most impactful severe weather events across the Mid-Atlantic then we have had in some time,” National Weather Service meteorologist Chris Strong said in a Facebook live briefing.
The storm system comes as WPC also warned of “dangerously hot daytime temperatures” in Texas and portions of the southeast and Florida for Monday and Tuesday, which could reach between 35 to 40 Celsius.
There will be an elevated fire risk due to dry ground conditions, low relative humidities and gusty winds, WPC said.
The turbulent weather comes as global heat records have been shattered this summer, with scientists saying that climate change is to blame.
— with files from the Canadian Press and the Associated Press.