Northeast Braces For Severe Thunderstorms And Flooding As Storm Lingers

The break in the stormy pattern for the Northeast will be a short one as an atmospheric traffic jam directs more rounds of rain and locally severe thunderstorms into the region from late this week to early next week. As more rain pours down on the saturated ground, the potential for significant flooding will return to the region, AccuWeather meteorologists warn.

A large storm will meander near the shores of Hudson Bay, Canada, into next week. At the same time, disturbances in the jet stream will spin around the storm, like spokes in a giant wheel, and cause showers and thunderstorms to gather over the Midwest and pivot into the Northeast in the days ahead. As these disturbances approach the Northeast, they will accumulate moisture from the Gulf of Mexico as well as the warm waters of the nearby Atlantic.

The storm that swamped the region from this past Sunday to Monday behaved more like a tropical system as it produced rainfall rates ranging from 1-3 inches per hour, according to AccuWeather Senior Meteorologist Dave Dombek.

“[Ocean] water temperatures in the mid-Atlantic region are several degrees above average this summer and are currently more like levels sometimes seen in late August, which is typically the peak of the warmth,” Dombek stated. Water temperatures ranged from the mid-70s to the low 80s F and were 3-8 degrees above average early this week.

The warm water then becomes a source of tropical moisture and fuel for the disturbances rolling in from the Midwest.

“At the same time, the disturbances from the Midwest will tend to slow down and pivot northward rather than progress quickly out to sea upon reaching the Atlantic coast,” Dombek said. “This action will cause much more rain to be unloaded on some areas as opposed to a storm system that continues to move right along.”

While a setup exactly like the one that resulted in 5-10 inches of rain and locally higher amounts from parts of Pennsylvania to eastern New York and Vermont is not likely, multiple smaller-scale events may occur with overlapping rainfall over an approximate six-day period from Thursday to next Tuesday in the Northeast.

At least three rounds of downpours and thunderstorms are likely to progress slowly from the central Appalachians to the mid-Atlantic coast and New England. The first will swing through the region from Thursday to Friday. The second round is likely to advance across the area from Saturday to Sunday. And the third round is projected to roll along from Monday to Tuesday.

As more rain falls on a progressively wetter landscape, the risk of small stream flooding and rises on some of the rivers will increase. Small streams and rivers that are already running high could spill out of their banks. Similarly, some streams which experienced flooding recently in Pennsylvania, New York, Vermont and other states could flood again.

AccuWeather forecasters emphasize that it will not rain continuously from Thursday through Tuesday. In fact, much of the time during the six-day period may be rain-free. However, when it does rain, it may pour for several hours and deposit several inches of water during that time. Rainfall of this intensity is more than enough to overwhelm storm drains and lead to rapid rises along small streams.

Forecasters urge those who live along small streams to closely monitor weather alerts. Heavy rain that occurs miles upstream can trigger a flash flood with little or no notice.

A general 1-4 inches of rain is likely to fall on the Northeast from Thursday through Monday. However, the AccuWeather Local StormMax™ rainfall is initially estimated at 6 inches. As the pattern evolves, expected rainfall amounts will be re-evaluated by meteorologists, as there is the potential for locally higher totals.

One round of severe weather is poised to strike areas from western and central Virginia to New York’s upper Hudson Valley, the Berkshires of Connecticut and western Massachusetts and the southern part of Vermont’s Green Mountains Thursday afternoon and evening.

Along with the likelihood of flash flooding, some of the storms will pack wind gusts between 50 and 60 mph with an AccuWeather Local StormMax™ of 70 mph. However, since a couple of isolated tornadoes could also occur, there is some risk to lives and property, AccuWeather forecasters say.

As each disturbance swings through, a new round of severe weather will be possible from the Appalachians and eastern Great Lakes region to the mid-Atlantic coast and parts of New England.

Each region may experience a round of severe thunderstorms and/or heavy rainfall every other day through early next week with some exceptions. In some locations, rain or storms may roll through every day. In others, there may be a break in between that lasts two days or more.

Produced in association with AccuWeather