A flash flood watch for the entire state of Pennsylvania was issued through Thursday night. Rush-hour commuters tried to get to work in the morning amid torrential downpours and dark skies that made it look like nighttime.
In New Jersey, officials opened the soaked state's Emergency Operations Center on Thursday morning to monitor the storm's progress. The National Weather Service issued a flood watch for most of the state. Forecasters predicted 1 to 2 inches of rain will fall on swollen rivers and streams. As thunderstorms rumbled across the southern and central parts of the state, thousands of residents were left without power.
In northern New York, rain sent rivers and streams over their banks, leading to evacuations and road closures.
Overnight, thunderstorms that punched through northern Illinois caused significant wind damage, mainly in rural areas west and south of Chicago. The city was largely spared. The weather service said intense winds estimated to have reached 70-80 mph in some areas snapped large trees at their trunks or uprooted them entirely.
By early Thursday, though, the derecho that had been forecast hadn't developed.
"With each hour that goes by, it's less likely," said Greg Carbin of the storm prediction center.
A derecho is a storm of strong straight-line winds spanning at least 240 miles. The systems are distinctive and take on a comma or bow shape, and usually have a large area of very cold cloud tops not typically seen in an ordinary thunderstorm.
While the Midwest dodged a derecho, several tornadoes, large hail and flooding did some damage Wednesday.
In the small town of Belmond, Iowa, about 90 miles north of Des Moines, Duwayne Abel, owner of Cattleman's Steaks & Provisions restaurant, said a tornado demolished part of the building. No one was in the restaurant at the time.
"I was, oh, eight miles west of town and I looked toward town and I could see a funnel cloud, having no idea it was exactly where our restaurant was," Abel said. His wife and an employee were able to get out of the restaurant and sought shelter in a basement.
Last year, a derecho caused at least $1 billion in damage from Chicago to Washington, killing 13 people and leaving more than 4 million people without power, according to the weather service. Winds reached nearly 100 mph in some places. In addition to the people killed in the storm, 34 more died from the heat wave that followed in areas without power.