Potent thunderstorms wrung out of a waterlogged atmosphere deluged the region Tuesday with flooding rains — more than 7 inches in Chester County — thunderstorm gusts, inch-diameter hail in South Jersey, and a spoiled day for hundreds of visitors to the Philadelphia Flower Show.

The rains targeted the Downingtown area with a singular ferocity, and the National Weather Service’s flood warnings remained in effect. On Tuesday night, major flooding was occurring near Downingtown along the East Branch of the Brandywine Creek, which had risen past 12 feet; flood stage is 7 feet.

The Brandywine at Chadds Ford was forecast to crest at 10.6 feet, or 1.6 above flood stage. A warning for minor flooding was in effect until Wednesday evening.

The 7.16 inches reported just east of Coatesville near Modena — about two months’ worth — was verified by radar, said Trent Davis, meteorologist at the National Weather Service Office in Mount Holly, In Downingtown, 5.4 inches was measured.

Lightning forced guests attending the often weather-bedeviled Philadelphia Flower Show ― which is being held outdoors and in June for the first time ever ― to evacuate the FDR Park site Tuesday afternoon, and the forecast for the rest of the week isn’t exactly promising.

Showers are likely again Wednesday, possible on Thursday, and likely again on Friday. More downpours Wednesday aren’t out of the question, the weather service said.

In between raindrops, a heat advisory is effect for Wednesday for Philadelphia and the surrounding area for heat indices in the upper 90s.

Chester County was the thunderstorm punching bag Tuesday, and numerous water rescues were reported.

A school-bus driver reported floodwaters at Caln Meetinghouse and Fisherville Roads, saying he tried to turn around but was blocked in by traffic.

As the storms moved east, they pounded Camden County with thunderstorm winds and inch-diameter hail.

The mayhem began shortly after noon on a day when the atmosphere was marinating in water vapor. As the slow-moving storms migrated eastward, the Flower Show yielded to the threat of lightning and ordered everyone to leave.

» READ MORE: The curse of the Philadelphia Flower Show: Snow strikes again

“We got everyone out of the show safely,” said spokesperson Sin Gogolak, adding that the show would not reopen until officials received an all-clear from the weather service and the city Office of Emergency Management.

The atmosphere, however, appeared to be in slow motion, said Davis, and the storms persisted.

At one point, nearly 10,000 Peco customers, about half of them in Chester County, were without power Tuesday afternoon. Lightning reportedly struck a house in Maple Glen, Montgomery County, and wires were down in Springfield, Delaware County.

On the plus side, the storms offered a refreshing respite from what has been an oppressive air mass. The rains shaved 10 degrees off the official reading at Philadelphia International Airport, from 86 to 76, but the heat and humidity are due back Wednesday, and the weather service says some of the showers could once again be heavy.

The Flower Show has weathered the vicissitudes of nature through the years ― even though this is the first time it has been held outdoors and wasn’t held in March.

Snowfalls, along with scare forecasts, had held down attendance in some previous years, and the opening day of the 1993 show happened to coincide with a historic blizzard.

Yes, it did shut down that day.

Staff writer Diane Mastrull contributed to this article.