Potent storm to trigger flooding, tornado threats in Ohio Valley and Northeast

By Alex Sosnowski, AccuWeather senior meteorologist

The caboose in a train of storm systems will travel from the Midwest on Wednesday to the Northeast on Thursday with concentrated heavy rain and the potential for severe thunderstorms and tornadoes.

Round after round of rain in some areas and thunderstorms in others have riddled the Ohio Valley, central Appalachians and mid-Atlantic region in recent days, leaving the region vulnerable to flooding.

Stormy weather will continue to slow travel, foil outdoor plans and even pose risk to lives and property in some cases before the weather improves late in the week.

Through Wednesday, the weather pattern will favor sporadic areas of downpours and locally heavy, gusty and isolated severe thunderstorms.

While the greatest threats to people and property will be from flash flooding and lightning strikes, a small number of the storms through Wednesday can produce damaging winds, hail and perhaps isolated tornadoes.

Rain on saturated ground to increase risk of flooding

From Sunday morning to Tuesday morning, southern parts of Indiana and Ohio have received 8 inches of rain. From 1-6 inches of rain have fallen on the balance of the Ohio Valley and the western slopes of the central Appalachians. Local rainfall amounts to 2 inches have fallen closer to the mid-Atlantic coast.

This image shows radar estimated rainfall spanning Sunday morning, June 16, to Tuesday morning, June 18, 2019. (NOAA)

The landscape is primed for flooding. Additional heavy rainfall is likely to trigger urban and small stream flooding through Thursday.

Rises on the secondary rivers in the region are likely. These include some of the tributaries of the Ohio, Potomac, Susquehanna and Delaware rivers.

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Feisty storms to rumble through southern Appalachians, mid-Atlantic

People living along or camping in unprotected areas of these water ways should closely monitor the situation.

Much of the rain thus far has avoided the lower Great Lakes and the northern parts of New York state and New England.

However, the largest and strongest storm system of the bunch will force heavy rain into many of these northern tier locations by Thursday.

The steadiest rain is likely to avoid southeastern Virginia and the lower part of the Delmarva Peninsula as it has done so far.

Since these areas have received significantly less rain in recent days, compared to others, any flooding is likely to be limited to low-lying areas of streets and highways.

Heavy, gusty thunderstorms may turn violent with a tornado risk

The same storm system will raise the bar for severe weather in the Ohio Valley spanning Wednesday and Wednesday night and the central Appalachians and mid-Atlantic on Thursday and Thursday night.

As the storm moves through, severe storms have the potential to occur on a more regional basis and could be locally violent.

"Should the storm strengthen quickly and there is sufficient sunshine to heat the region ahead of the thunderstorms, a violent severe weather outbreak that includes tornadoes may result," according to AccuWeather Meteorologist Jake Sojda.

A number of communities may be hit with winds that can knock down trees or break tree limbs and cause minor property damage.

As the storm system slides eastward, where warm and humid air exists, there is the possibility of several tornadoes, some of which may be strong.

As has been the case so far this week, a few of the bigger storms can also produce hail.

Cities at risk for violent storms on Wednesday include Indianapolis, Cincinnati; and also Nashville, Tennessee.

On Thursday, the entire corridor from Charlotte, North Carolina, to Washington, D.C., Philadelphia and perhaps New York City may be at risk for dangerous and damaging storms.

AccuWeather will continue to provide updates on the situation. Download the free AccuWeather app to receive severe weather and flash flooding watches and warnings. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

In the wake of the storm, a break from rain may last one to three days with the longest stretch of dry weather likely in New England and northern New York state.