With the atmosphere well-juiced and energized, approaching fronts ignited strong thunderstorms late Thursday, with downpours that deluged parts of the region with waterfall-like rains and set off flood warnings.

Heavy rains persisted well into the evening in some areas, and more storms are possible Friday, the National Weather Service Office in Mount Holly said.

In Montgomery County, flooding was reported on Route 422 near Pottstown — where more than three-quarters of an inch of rain fell between 6 and 7 p.m. The weather service also posted reports of flooding in Philly on I-676 near Logan Square and on I-95 near the Betsy Ross Bridge; on Route 1 in Fairless Hills, Bucks County; and on the Blue Route near Media, Delaware County.

During the evening the storms appeared to be “training” — that is, hitting the same areas repeatedly — along a southwest-to-northeast axis just to the west of Philadelphia, said Sarah Johnson, a lead meteorologist in the Mount Holly area.

“The storms don’t have a lot of west-to-east movement,” she said. Some of that rain eventually did migrate eastward.

The weather service had warned that between 5 and 8 p.m. the storms “may start to slow down,” and that evidently is what happened.

To the east, where a strong thunderstorms struck extreme South Jersey, a gust past 40 mph was reported at Cape May Point.

The nastiness should not affect the setup for the first-ever outdoor Philadelphia Flower Show, which is scheduled to open Saturday and continue through June 13. Vulnerable exhibits are being covered from the rain, said spokesperson Sin Gogolak.

The open-air exhibits actually should prosper from the rain, and the presumed subsequent sunshine, Gogolak said.

They could get a decent soaking. More showers are possible Friday and Friday night, followed by a major warm-up.

Those attending the show might want to bring water bottles.

It appears that the region will experience its first heat wave of the season starting Sunday with the first of several days with forecast highs in the 90s.