Members of the high school graduating class of 1974 in Moore, Okla., had taken their seats in the football stadium under darkening skies.

The class president welcomed the crowd. Then the principal, looking out at the clouds, declared all the students graduates and told those in attendance to find shelter immediately.

“The sky turned pea green, horrible clouds rolled in, and sirens started going off,” said Nuala Murray South, one of the graduates.

Sterling Crim, another graduate, grabbed the hand of his girlfriend, LeAnn Boyd, and dragged her under the bleachers next to the brick wall of a concession stand.

The tornado never materialized, touching down instead west of Moore. But the day — and the rite — were ruined.

The graduates were soaked, their clothing stained by blue paper caps. They unceremoniously picked up their diplomas from the high school later. But long after going off to college, starting careers and families, many harbored a hope that they would eventually cross the stage.