We did not intend to hurt anyone. Our goal had been to help our neighbors in the Houston area get out of danger. Yet in 2015 the phone started ringing, and Internet messages started piling up, saying we were making safety worse. “You are doing a disservice,” said one public official from a district on Houston’s northern edge. A meteorologist chastised us: “How come you are telling people they are at low risk for flooding when there is flooding all around them?”