The deadliest tornado to sweep across this country in the last 56 years began in Marion County, a few miles from the Mississippi line, where the highway signs now bend toward the ground along U.S. 78 west of Hamilton.

Trees blew over. Hamilton lost power. Yet for 10 miles, the massive storm largely churned above the wilderness, growing in ferocity, sucking moist afternoon air high into rotating clouds. Soon the system would spawn a tornado measuring more than a mile across.

The National Weather Service also reports evidence of satellite vortices, essentially twisters within twisters. Mesocyclone winds swirled along the outside edges, gusting toward the center. [ blog.al.com ]

This natural fury first encountered civilization at Hackleburg. A quiet town of 1,600 in the northeast corner of Marion County, the still-standing water tower boasts of a high school baseball championship in 2007. The chief employer had been the distribution center for Wrangler jeans.

Six days after the storm, Tommy Quinn picked through his few recognizable belongings. He held a picture his older brother had painted years ago and a clamp for his piano.

"I was thinking nothing is going to happen," said Quinn, 21, standing near what had been his childhood home. Listening to the weather report on TV, his sister-in-law chose to pack suitcases with diapers and photo albums and urge the family to the storm shelter.

On the Enhanced Fujita scale, a tornado ranks at the highest level of EF-5 when wind speeds top 200 mph. At that strength, brick homes are swept away. Concrete walls give way. Steel girders bend.

About a dozen separate tornadoes claimed more than 230 lives in Alabama on April 27. The storm that the National Weather Service now calls the Hackleburg Tornado, the one that traveled 132 miles and passed north of Huntsville, was the only one rated EF-5.

Quinn said he grabbed his wallet and car keys. "It got dead quiet," he said. "Then we started hearing that rumble, that deafening roar."

In Hackleburg, at the beginning of a 90-mile trail of nonstop scarring, blank slabs provide the only evidence of missing homes. A Chevy pickup sits unfolded as though made of paper, a thin tree piercing the truck lengthwise. Trees are shorn of limbs and bark. Rainwater swells in deep pits where root balls were ripped from the ground. Everywhere are the contents of exploded homes.

Quinn's brother, stationed at the shelter's only window, saw bricks fly by. Quinn's dad held fast to the shelter door. The steel reinforced roof seemed to vibrate. Quinn said it lifted six inches. "It lasted about 15 seconds. It sounded like a low organ note," he said.

Then came the cries for help.

Quinn noticed his father was bleeding. They all were covered in dirt. Quinn said the family realized the house was gone, save for one living room wall. The calls emanated from a crater where moments ago stood Emmanuel Baptist Church.

Quinn said he and his brother and his father and a truck driver, a man who appeared from nowhere and seemed to be bleeding from everywhere, began to tug at the toppled bricks. They uncovered the pastor and his wife and several children in the church basement. Her legs were pinned under cinder blocks. "You could see the muscles in her hand. His back was broken," Quinn said.

Quinn said some children had been saved by a cocked metal shelf. The trucker's semi had spun in the air nearby, its cargo breaking free. Unspooled steel covered the hill. A policeman passed by on foot without stopping to dig.

A second tornado was coming.

90 miles of scarred earth

The day was unusual in many ways. Greg Carbin, a meteorologist at the National Oceanic and Atmospheric Administration's Storm Prediction Center, estimates a dozen separate tornadoes led to loss of life in Alabama on April 27.

Scores more descended from the clouds. Carbin said they will probably never have a firm count of all the lesser twisters. In Alabama, the storms killed 236. Across the South, 340 died, as at least 300 separate tornadoes touched down. It was the deadliest 24-hour period for tornadoes since 1925.

But even on April 27, the Hackleburg Tornado stood apart.

It's thought to have killed 70 people in Alabama. For nearly 90 miles, it stayed on the ground.

"It's quite possible the tornado will get an EF-5 rating for the entire path," Carbin said.

This one twister, he said, became the deadliest single tornado since 1955, when a tornado struck Udall, Kan., and claimed 80 lives.

Yet, after Hackleburg, the EF-5 again and again seemed to veer away from people and downtowns, sparing malls and schools, just clipping the northwest corner of Decatur, hitting an improbable gap between Athens and Madison, overshooting Huntsville and fading before Hazel Green.

Tornadoes are still poorly understood, Carbin said. There was a cold front in the lower Mississippi Valley and intense low pressure from Missouri. The atmosphere lifted. Moist air was sucked into the upper atmosphere, fueling rotation. But the same ingredients don't always create tornadoes, he said.

Things have to line up just right. Or wrong.