Drenching storm bringing flood risk to Northeast
In addition to flooding downpours, forecasters are warning that some thunderstorms could turn severe and produce damaging winds and even an isolated tornado.
By
Ryan Adamson, AccuWeather meteorologist
Updated Sep 23, 2021 9:08 AM EDT
AccuWeather forecasters say that periods of steady rain and thunderstorms that reached the Northeast on Wednesday will continue to generate a flash flood risk across the region throughout the day on Thursday.
A cold front moving across the country has been very slow in its trek, and the rain associated with the front will pose problems farther to the east through the second half of the week.
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"The risk of flooding began Wednesday night and will persist into Thursday as an area of low pressure develops," said AccuWeather Meteorologist Matt Benz.
In addition to the developing low pressure causing the front to slow down, an area of high pressure off the East Coast will create a bit of an atmospheric roadblock. This will cause the rain to last longer in any one location, further enhancing the flood threat. Both the duration and intensity of the rain will be factors for any potential flooding.
"Plenty of deep, tropical moisture will get ingested northward along the cold front where rainfall rates can be enhanced with any embedded thunderstorms," Benz added.
AccuWeather forecasters say motorists should remember the adage "turn around, don't drown," and never drive through floodwaters.
"As the front slows, heavy rain associated with it can pivot over portions of Ohio, Michigan, Indiana, Pennsylvania, western and central New York state and northern Maryland," AccuWeather Senior Meteorologist Alex Sosnowski said. Some areas could be under a zone of heavy rain for an extended period,
"A 'firehose effect' can occur which means rain may pour down at the rate of 1-2 inches per hour or more for several hours," Sosnowski added.
This torrential rain is most likely to occur into Thursday across southeastern Michigan, central and eastern Indiana and northwestern Ohio. Over 121,000 customers in Michigan alone were left without power amid the storms Wednesday, according to PowerOutage.US. As rain and wind continued through Thursday morning, that number had risen to more than 190,000 in Michigan.
Rainfall of this magnitude is not only likely to trigger rapid flooding in urban areas, but very fast rises in water levels can occur along small streams and some of the rivers in the region.
"The steep terrain in the central Appalachians intertwined with communities along streams in Pennsylvania, West Virginia, northern Maryland and upstate New York will be at a heightened risk for dangerous flash flooding in this situation," Sosnowski said.
Flash flood watches have been issued in part of the eastern United States by the National Weather Service due to the threat of torrential rain.
Given the slow nature of the front, it will likely take until Thursday for the heaviest rain to reach the East Coast. The greatest risk for heavy rain will be Thursday in Philadelphia, Baltimore and Washington, D.C., with downpours likely not arriving in New York City until Thursday night.
"Because of low evaporation rates in September, compared to the middle of the summer, the ground has remained moist in the wake of Ida in areas farther to the east," Sosnowski said.
For this reason and due to a large number of paved surfaces farther east in the mid-Atlantic region, enough rain can pour down fast enough to trigger flash flooding Thursday.
"A general 1-2 inches of rain is forecast to fall with local amounts to 4 inches in the mid-Atlantic region, but a general 2-4 inches seem likely with an AccuWeather Local StormMax™ of 8 inches forecast from southeastern Michigan to central Pennsylvania and western New York," Sosnowski said.
Along with the likelihood of torrential rain and localized flash flooding, severe thunderstorms may erupt. On Thursday, the threat for severe thunderstorms, capable of spawning isolated tornadoes, will shift farther to the east along with the likelihood of heavy rain.
During the day Thursday, the threat for severe storms is forecast to stretch from central Pennsylvania through eastern Virginia and into eastern North Carolina. Cities at risk for damaging and dangerous thunderstorms on Thursday include Harrisburg and Allentown, Pennsylvania; Baltimore and Washington, D.C.
By Thursday night, the severe weather threat will shift to the area from southeastern New York state, far southeastern Pennsylvania and New Jersey to Delaware and southeastern Maryland. This threat includes the metro areas of New York City and Philadelphia.
Although a few showers or some drizzle can develop farther east Thursday, it won't be until Friday that the front crawls into New England and reaches cities such as Portland, Maine, and Boston. The rain can even linger into at least early Saturday in New England before the front finally moves offshore.
Following this front, a second system is likely to move into the Great Lakes Saturday. This ripple in the jet stream is likely to move northeastward into southern Canada by Sunday. Luckily, any rain with this system is likely to be much lighter and not last as long. No flooding problems are expected, forecasters say.
This second system will reinforce the cool air that the will be ushered in by the first front. With fall officially Wednesday afternoon, Mother Nature will be adhering to the calendar.
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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News / Weather Forecasts
Drenching storm bringing flood risk to Northeast
In addition to flooding downpours, forecasters are warning that some thunderstorms could turn severe and produce damaging winds and even an isolated tornado.
By Ryan Adamson, AccuWeather meteorologist
Updated Sep 23, 2021 9:08 AM EDT
AccuWeather forecasters say that periods of steady rain and thunderstorms that reached the Northeast on Wednesday will continue to generate a flash flood risk across the region throughout the day on Thursday.
A cold front moving across the country has been very slow in its trek, and the rain associated with the front will pose problems farther to the east through the second half of the week.
CLICK HERE FOR THE FREE ACCUWEATHER APP
"The risk of flooding began Wednesday night and will persist into Thursday as an area of low pressure develops," said AccuWeather Meteorologist Matt Benz.
In addition to the developing low pressure causing the front to slow down, an area of high pressure off the East Coast will create a bit of an atmospheric roadblock. This will cause the rain to last longer in any one location, further enhancing the flood threat. Both the duration and intensity of the rain will be factors for any potential flooding.
"Plenty of deep, tropical moisture will get ingested northward along the cold front where rainfall rates can be enhanced with any embedded thunderstorms," Benz added.
AccuWeather forecasters say motorists should remember the adage "turn around, don't drown," and never drive through floodwaters.
"As the front slows, heavy rain associated with it can pivot over portions of Ohio, Michigan, Indiana, Pennsylvania, western and central New York state and northern Maryland," AccuWeather Senior Meteorologist Alex Sosnowski said. Some areas could be under a zone of heavy rain for an extended period,
"A 'firehose effect' can occur which means rain may pour down at the rate of 1-2 inches per hour or more for several hours," Sosnowski added.
This torrential rain is most likely to occur into Thursday across southeastern Michigan, central and eastern Indiana and northwestern Ohio. Over 121,000 customers in Michigan alone were left without power amid the storms Wednesday, according to PowerOutage.US. As rain and wind continued through Thursday morning, that number had risen to more than 190,000 in Michigan.
Rainfall of this magnitude is not only likely to trigger rapid flooding in urban areas, but very fast rises in water levels can occur along small streams and some of the rivers in the region.
"The steep terrain in the central Appalachians intertwined with communities along streams in Pennsylvania, West Virginia, northern Maryland and upstate New York will be at a heightened risk for dangerous flash flooding in this situation," Sosnowski said.
Flash flood watches have been issued in part of the eastern United States by the National Weather Service due to the threat of torrential rain.
Given the slow nature of the front, it will likely take until Thursday for the heaviest rain to reach the East Coast. The greatest risk for heavy rain will be Thursday in Philadelphia, Baltimore and Washington, D.C., with downpours likely not arriving in New York City until Thursday night.
"Because of low evaporation rates in September, compared to the middle of the summer, the ground has remained moist in the wake of Ida in areas farther to the east," Sosnowski said.
For this reason and due to a large number of paved surfaces farther east in the mid-Atlantic region, enough rain can pour down fast enough to trigger flash flooding Thursday.
"A general 1-2 inches of rain is forecast to fall with local amounts to 4 inches in the mid-Atlantic region, but a general 2-4 inches seem likely with an AccuWeather Local StormMax™ of 8 inches forecast from southeastern Michigan to central Pennsylvania and western New York," Sosnowski said.
Along with the likelihood of torrential rain and localized flash flooding, severe thunderstorms may erupt. On Thursday, the threat for severe thunderstorms, capable of spawning isolated tornadoes, will shift farther to the east along with the likelihood of heavy rain.
During the day Thursday, the threat for severe storms is forecast to stretch from central Pennsylvania through eastern Virginia and into eastern North Carolina. Cities at risk for damaging and dangerous thunderstorms on Thursday include Harrisburg and Allentown, Pennsylvania; Baltimore and Washington, D.C.
By Thursday night, the severe weather threat will shift to the area from southeastern New York state, far southeastern Pennsylvania and New Jersey to Delaware and southeastern Maryland. This threat includes the metro areas of New York City and Philadelphia.
Although a few showers or some drizzle can develop farther east Thursday, it won't be until Friday that the front crawls into New England and reaches cities such as Portland, Maine, and Boston. The rain can even linger into at least early Saturday in New England before the front finally moves offshore.
Following this front, a second system is likely to move into the Great Lakes Saturday. This ripple in the jet stream is likely to move northeastward into southern Canada by Sunday. Luckily, any rain with this system is likely to be much lighter and not last as long. No flooding problems are expected, forecasters say.
This second system will reinforce the cool air that the will be ushered in by the first front. With fall officially Wednesday afternoon, Mother Nature will be adhering to the calendar.
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For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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