In the Philadelphia region, it was the strongest documented tornado in the period of record, and it swirled through Limerick, not far from the nuclear power plant, without warning.
In fact, the only warning Janice Rossi, who had just moved into the house on Victory Way, recalled was the wailing of her 4-month-old son, Jeremy, just before midnight. The crying woke her, and she planned to nurse him and put him back to sleep, but then she opened her eyes and couldn't believe what she was seeing inside her house.
"Gray snow," said Rossi, now 57. It was, she said, as though the house's insulation "was raining down on me."
Cold air blew from a shattered bay window on the opposite wall. The ceiling was caved in. The clean laundry she had neatly folded hours earlier was everywhere.
She didn't know what was happening, only that it was something horrible. Her husband was out of town. She grabbed Jeremy from his crib and banged on the door of her 8-year-old daughter's room; the winds had sucked the door shut.
She was able to get to Katie and her 6-year-old, Mathew. She went to a neighbor's house to call her husband, Dale, and told him to come home right away.
When Dale Rossi arrived at 3 a.m., Janice was at the hospital being treated for a twisted ankle. The children had taken shelter at the nearby Linfield fire station. He hugged them close, and they spent the next few hours there, waiting it out.
"As the sun started to rise, people started to think about what to do next," he recalled.
The Rossi home, just two doors away from the Petersen-Thompson household, was reduced to a shell. It was a year before they could move back.
The Limerick tornado and a strong twister that touched down earlier that night in Chester County were blamed for destroying or damaging 35 homes and businesses, and injuring at least 17 people in addition to the three fatalities.
Along with its ferocity, the Limerick tornado was a rarity in another way: At the time, the National Weather Service said that in the previous 100 years, fewer than 10 had hit Pennsylvania after 10 p.m.
The infrequency was one reason the weather service did not have a tornado warning up that night for Limerick. Also, the government was working bugs out of its brand-new Doppler radar system, and with so much heavy rain in the area, radar technology might have had trouble detecting the storm, said Dean Iovino, a meteorologist at the National Weather Service office in Mount Holly.
Chet Henricksen, who was in charge of the weather service office at the time, was the on-site investigator who determined that the twister was an F3 on the old Fujita scale, one with peak winds up to 206 m.p.h. In his career, said Henricksen, now retired, "I haven't seen one that even comes close" to Limerick's.
For the Rossi family, a crack on the front porch is now the only exterior sign of the horror of that July night, and the chaotic aftermath.
It took weeks for the family to find a temporary home a few miles away. In the interim, the family stayed in one room at the Pottstown Holiday Inn. The older children spent a few days with their grandparents in Buffalo.
They could not return to their damaged home and had to buy everything - clothes, pillows, a car, toys.
Even with a good insurance policy, which paid for the razing and rebuilding of their house, the couple were hurting financially. They had gone more than $100,000 over the insurance company's allotment, Dale said.
The emotional strain was just as difficult to overcome.
"You realize in retrospect you go into a depression," he said. "You spent all that time and money and it's destroyed."
After the tornado, he recalled the incredible sadness of the funeral, and how right before the burial, 11-month-old Mikhela was moved from the coffin of her father to that of her mother.
"That was painful. It wouldn't have been as big a deal before I had kids," Dale said. "It tore your heart out."
Afterward, some survivors built storm shelters in their basement, he said, where they go whenever there's a storm warning.
For Katie Rossi, now 28 and a librarian, the aftermath of the tornado did yield one silver moment. Right after it hit, she was beside herself that she was unable to find her Madeline, the raggedy doll with the red-yarn braids.
Miraculously, someone she didn't know found the doll - she doesn't know where - and returned it.
That's the Madeline resting safely today in the Rossis' basement.