Mary Sue Meyers' grandparents were killed in a 1924 tornado in Marengo, Wis., a dozen miles south of Lake Superior. Her orphaned mother, Elma Holma, was 19 and suddenly found herself raising her teenage siblings. When she had children of her own, Elma passed down her fear of twisters.

"She would tell us: 'If you ever look up in the sky and see green teacups, take shelter,' " Meyers said.

Forty-one years after her grandmother died, Meyers was in her 20s, living in Fridley and raising daughters Dawn, 4, and Chris, 6 months. On May 6, 1965, the pounding rain morphed into hail pelting the rooftops around 6 p.m. "I picked a large hailstone off the steps and looked at the sky and said, 'Oh my gosh' when I saw the green sky and puffy teacups." It's the light refracting off the hail that turns the sky greenish.

She shuffled the kids to the basement. Her husband, Don Meyers, Fridley High School's athletic director and wrestling coach, was driving home from a baseball game. "I looked west and said to myself: 'Those are some ugly clouds.' "

He found Mary Sue sprawled over her daughters in the basement. "My wife was always terrified of tornadoes," Don, 80, recalled 50 years later. He blanketed his body over his wife and kids — bracing for the worst.

Just then, the worst string of tornadoes to ever attack the Twin Cities area came bearing down. The first of six distinct funnels slammed Glencoe around 5:30 p.m. Waves of the storm kept up their onslaught for three hours — with more than 20 touchdowns. Although debate still rages over whether two or three tornadoes were responsible, two dozen hook echoes were detected on the ancient World War II battleship radar that the U.S. Weather Bureau still employed in 1965.

But there was a bit of newer technology put to use as well. The Cold War-era civil defense sirens, installed in the 1950s amid fears of Communist attacks, were blasted for the first time in Minnesota to warn people of danger swirling their way.

Thirteen people died and nearly 700 were injured. Among the dead were 4-month-old Helene Hawley and 64-year-old Annie Demery (a grandmother to 17) — both from Fridley.

The suburb just north of Minneapolis was in the vortex, with one in four houses hit — 1,100 were damaged and 425 destroyed. The city suffered nearly $15 million in losses — including $5 million to school buildings — more than $100 million in today's dollars.

"I've never seen anything like it," Vice President Hubert Humphrey said in Fridley after a tour. "The damage I've seen is comparable to a war."

The tornadoes were the culmination of a wicked weather year for Minnesota. In March, a blizzard forced hospitals to use snowmobiles to transport blood. In April, the state drowned in a 500-year flood as rivers swelled to record levels.

"It was a trifecta of natural events unlike anything we've ever seen," said Rob Brown, 77, a phone-call screener that May 6 night at WCCO Radio. None of the TV or radio stations had radar back then, so Brown fielded calls on two call-in lines usually used for a quiz show.

Using a ballpoint pen and a road map, Dick Chapman and Charlie Boone relayed what listeners were reporting. Their audience included a 68 percent chunk of Minnesota radio listeners, so they might have saved countless lives. They'd go on to win a series of awards because, before then, storms were covered the next day — not live.

"I still remember the noise and lightning flashing through the walls," said Allen Taylor, a Coon Rapids researcher who has written two books on the 1965 twisters.

At Fridley Junior High School, students and parents had gathered for a science open house when the storm struck.

"We walk into the art room and my teacher yells, 'Everybody out of the room! It's a tornado hitting the other side of the building!' " wrote Tara Arlene Innmon, then 14, in memoir excerpts published in Fridley's community newsletter.

She and her aunt carefully walked through debris in the darkness while others crammed into interior rooms amid fears of more twisters. The storm ripped the roof off the school. One woman suffered a broken back from falling debris, but no one was killed at the school event.

"Just as quickly as it hits, it is gone," Innmon wrote. "The roaring, ripping apart stops."

The storm jumped the Mississippi River just east of where the Meyers family huddled in the basement. A strip mall a half-mile away was obliterated.

A massive cleanup commenced. Taylor's research shows that churches were rebuilt larger and attendance mushroomed. "People were thinking, 'We shouldn't be here,' so they headed to church in greater numbers," he said.

Don Meyers remembers how "every time there was a dark cloud, everyone in Fridley was outside looking at the sky, wondering if this was another one of those storms."

Thankfully, folks in Fridley haven't seen another quite like May 6, 1965.

Curt Brown's tale on Minnesota's history appears each Sunday. Readers can send him ideas and suggestions at mnhistory@startribune.com