Tennis attendees use signs to step over puddles as they exit the grounds during a massive downpour of rain from Ida on Wednesday at the 2021 US Open Tennis Championships in New York City. Photo by John Angelillo/UPI | License Photo
Sept. 5 (UPI) -- After Ida brought deadly flooding and tornadoes to the Northeast last week, cooler conditions are expected to be replaced by more stormy weather and the potential for severe thunderstorms as the week progresses.
Deadly flooding and destructive tornadoes descended upon the Northeast last week as Ida charged through the region. New York City set a record for most precipitation received in one hour after recording 3.15 inches of rain last Wednesday evening. Historic water levels were reached as extreme rainfall caused rivers to rise.
"The general 4-8 inches of rain and locally higher amounts that fell from southern Pennsylvania to northern New Jersey, southeastern New York state and southern New England dumped 700 million to 1.4 billion gallons of water per square mile, which was too much for rivers such as the Schuylkill, Conestoga, Raritan, Passaic and Yantic to handle," AccuWeather Senior Meteorologist Alex Sosnowski said.
Fortunately, waters have already begun receding due to drier weather, especially along the smaller streams. The Brandywine Creek in Wilmington, Del., which rose well above major flooding stage at 23 feet on Thursday, has since returned to its regular levels.
The Passaic River in New Jersey, however, remained above flooding stage at several locations as of Sunday morning. Along the Passaic at Pine Brook, New Jersey, water levels are forecast to dip below major flood stage on Sunday evening. Luckily, the weather will still offer more time for water levels to recede.
On Sunday, clouds began to gather from the next weather system in the Northeast.
"A weak cold front is forecast to shift through the Northeast on Sunday," AccuWeather Meteorologist Adam Sadvary said. This will bring a change away from the dry pattern, and instead bring with it some spotty showers and thunderstorms.
Thankfully, these storms are not expected to be severe or bring heavy rainfall, so any rivers and creeks that are still swollen should not elevate to dangerous levels once again. Instead, they're more likely to spoil outdoor plans for a brief time and bring a slight uptick in humidity.
"These showers and thunderstorms across the Northeast may briefly hinder cleanup efforts," AccuWeather Senior Meteorologist Tyler Roys said.
Dry weather is forecast to punch eastward and expand on Monday and then stick around through Tuesday in most locations of the Northeast.
Early this week, temperatures will remain near to slightly below normal, though, allowing residents to turn off their air conditioners across the Northeast into the Tennessee Valley. In the Northeast, average daytime highs range from the low 70s across the northern tier to the middle 80s near the Chesapeake Bay.
Nighttime temperatures in cities like Pittsburgh are forecast to fall a few degrees below normal each night, making for an early taste of autumn as Labor Day gets underway.
"The next threat for potentially severe weather across the Northeast is expected Wednesday afternoon into early Thursday with the approach and passage of a more potent cold front," Sadvary said.
Heavy thunderstorms, and perhaps even more localized flash flooding will be possible during this event.
AccuWeather forecasters are reminding motorists to never attempt to drive through floodwaters. Flash flooding is particularly dangerous and difficult to spot while in a vehicle. Reduced visibility and ponding of water on roadways is also possible.
These storms also bring the potential for gusty winds, which can be dangerous while the ground is saturated. When the earth is saturated, the wind can more easily topple trees, which can damage power lines and cause outages.
This same front can play a role in the tropics after crossing through the East this week. As it sweeps into the Atlantic, it might keep Hurricane Larry from approaching the United States, though there is still time for a variety of variables to change and adjust Larry's trajectory.