In 1999, the first few flaring storms near the Red River died quickly. Near Lawton, a super-cell thunderstorm organized into the familiar anvil shape, caused by rising clouds flattening against the troposphere, and at 4:45 p.m. began spinning up twisters.
It was the ninth tornado that made the record books. A9, as it was initially labeled by the National Weather Service, arose over Chickasha and tracked northward along I-44. The National Weather Service in Norman, which already had issued a tornado warning, sent higher-level alarms hoping that people would take shelter: the first-ever “tornado emergency.”
A mile-wide mass of dirt, rain, wind and debris crossed into Bridge Creek west of Newcastle, where it shredded a mobile home community. Turning east, the twister crossed I-35 and entered Moore, where it leveled one neighborhood after another, destroying 600 homes. It creased the parking lot at Crossroads Mall and cut through Del City and Midwest City before losing steam.
A mobile Doppler radar clocked the wind speeds at 300 miles per hour, the most powerful tornado ever recorded. It was the first to cause more than $1 billion in damages.
That one tornado alone was historic. But also, with an atmosphere packed with convective energy, one super-cell after another appeared, producing 71 tornadoes in Oklahoma.
The Bridge Creek-Moore twister killed 36 people. Yet it could have been much worse. The tornado was on the ground for more than 35 miles, allowing time for warnings to be widely broadcast. The early evening time meant children already were home from school.
Every major tornado prompts a lessons-learned assessment. The first from 1999 was the danger of taking shelter under highway overpasses. Three of the 36 people killed by A9 were ripped away from those spots. Overpasses serve to tunnel tornado winds, making them faster and deadlier.
The second was the need for shelter. Like on May 20, broadcasters warned people to seek shelter in underground or above-ground safe rooms. Traditional precautions, like huddling in a bathroom or closet, were useless against a powerful EF-4 or EF-5. Mobile homes and cars are the most dangerous places to be.