Del City, Okla. ? Late in the afternoon of May 3, 1999, Chris Stiles’ then-8-year-old son met him at the front door of their southwest Oklahoma City house as Stiles arrived home from work.

“Dad, there’s a tornado coming, and it’s bad,” Stiles recalls his son, Christopher, telling him. “You need to do something about it.”

Besides his son’s pleadings, one other thing caught Stiles’ attention that night — “the intensity of the newscasts” and the weather warnings issued as the twister approached the Oklahoma City metropolitan area from the southwest. Forecasters used terms rarely heard before, such as “tornado emergency,” to emphasize the danger of the approaching storm.

Stiles, then the football coach at nearby Westmoore High School, squired his family and another to safety in the school’s field house while the powerful twister leveled much of the Eastlake subdivision in which they lived.

By the end of the day, twisters spawned by the same storm system had killed 46 people in Oklahoma and Kansas — a number meteorologists said could have been much higher, especially with one of the more powerful tornadoes ever recorded cutting a swath southwest-to-northeast across the heavily populated Oklahoma City metro area.

The outbreak 10 years ago Sunday “went a long way to heighten public awareness of what happens in a long-track violent tornado, that it’s a serious deal and can happen and you have to plan for it ahead of time,” said David Andra, the science and operations officer for the National Weather Service office in Norman.

Not only did the public become more aware, he said, forecasters were able to glean lessons from the outbreak that still are being processed, 10 years later.

One thing forecasters learned that day, he said, was that even the most devastating and intense tornado outbreaks could be difficult to predict.

The conditions seemed ripe for such storms that day, but even so, “through the day, we had to build up the confidence to forecast it,” Andra said. Originally, forecasters thought the storms would be “further west and later in the day than it actually did, and there were definitely more tornadoes than we expected.”

According to the National Oceanic and Atmospheric Administration’s National Severe Storms Laboratory in Norman, 74 tornadoes touched down that day in Oklahoma and Kansas.