Radar data can estimate rainfall to a fairly accurate amount. The rain data in the case of the deadly tragedy that unfolded in the Texas Hill Country last weekend shows exactly why the area around Camp Mystic and the Guadalupe River, outside of San Antonio, had such a raging flash flood.

Generations of parents sent their daughters to the Christian camp on the Guadalupe. It suffered floods over the years but no one foresaw tragedy.

The first drops of rain had yet to fall when Ainslie Bashara, a counselor at Camp Mystic, noticed that one of the younger girls had begun to tear up. They were walking back to their cabin, Giggle Box, as another storm swelled over the Texas Hill Country. The girl feared what was coming, so Ainslie wrapped an arm around her.

It’s a mystery to me why they weren’t taking proactive steps to move structures,” said Syracuse University associate professor Sarah Pralle.