Repeating downpours to create dangerous flooding risk from Ohio Valley to mid-Atlantic
A series of systems will produce rounds of drenching rain, torrential downpours and thunderstorms over roughly the same swath from the Ohio Valley to the central Appalachians and mid-Atlantic coast this week. As the last system in the series moves into the Northeast later this week, some 115 million Americans will experience heavy rain or gusty winds, or some combination of both, at various points.
The pattern could become worse than just disrupting outdoor activities and slowing travel. Lives and property may be at risk where downpours repeat and/or rain persists.
Through Thursday, the area from Kentucky and southern Illinois through Pennsylvania, New Jersey, Maryland and Delaware will receive a general 2-4 inches of rain. An AccuWeather Local StormMax™ of 8 inches is anticipated.
Most of the large rivers in the region should be able to handle this amount of rain over an extended period with a minor to moderate rise.
However, hourly rainfall may exceed an inch and could be as high as 3 inches in extreme cases.
Some small streams will rapidly rise and overflow their banks. More than one flooding event can occur along particular small streams this week.
People living along or staying at campsites near small streams should keep a watchful eye for flash flooding. In situations such as this, it may be safer to camp on higher ground.
The periodic flooding of streets and poor-drainage areas in urban locations is likely.
Be sure to take an umbrella and wear waterproof shoes when heading out this week. (Pixabay photo)
Motorists should anticipate delays and may need to alter their routes to avoid driving through flooded areas.
Expect some of the secondary rivers to rise significantly with the potential for flooding in unprotected areas.
A lull in the heavy rainfall may develop on Wednesday. However, the risk is likely to increase, along with the severe weather threat in part of the region on Thursday.
In the 24 hours ending Sunday morning, Indianapolis received close to 4 inches of rain, with nearly 3.50 inches falling on Cincinnati.
What is causing the wet pattern and how warm might it get?
The wet weather pattern is being caused by a nearly stationary frontal zone. Storms will move from west to east along the frontal zone and cause it to meander a couple of hundred miles or so to the north and south through Friday.
North of the frontal zone, alternating episodes of rain and breaks of dry weather and sunshine are in store. Temperatures can rebound well into the 70s F during the afternoon hours.
Within the several-hundred-mile north-south zone along the front, the heaviest and longest-lasting rain will fall within the greatest risk of flooding. Within this zone, where clouds remain all day and/or during rainy episodes, temperatures will be mainly in the 60s.
South of the frontal zone, warm and humid conditions are forecast. Highs in this zone will be mainly in the 80s. However, even in the warm and humid air, an occasional shower or heavy, gusty thunderstorm is likely.
How long may the wet weather last?
From Wednesday night to Friday, as a stronger storm moves eastward along the frontal zone, it may be enough to break the atmospheric deadlock and allow some drier air to flow southward over areas receiving the bulk of the rain.
As this caboose in the train of storms moves along, drenching rain is likely to spread farther north than most days this week. This means that areas in upstate New York and northern New England are likely to get drenched prior to the end of the week.
Thursday could bring a significant threat for severe thunderstorms and tornadoes as well as flash flooding in part of the region.
The odds are against totally rain-free conditions despite a slight change in the weather pattern this weekend.
Download the free AccuWeather app for more precise details on the forecast for your area. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
