Operation Stormfury, the 1961-83 series of experiments to test the idea that cloud seeding could weaken hurricanes, helped make forecasting for Hurricane Camille the “most critical and hair-raising experience” of Robert Simpson’s long career as a hurricane scientist and forecaster. Simpson was director of the National Hurricane Center as Camille approached Mississippi as a Category 5 hurricane in 1969.

Why was this forecast so hair-raising?

As Camille approached, Simpson was lacking one of his most-important “forecasting tools—reliable airplanes that could bore into the storm’s center and discover just how strong it was—were not available,” Bob Sheets and I write in “Hurricane Watch: Forecasting the Deadliest Storms on Earth“. Simpson told us that the U.S. Navy, which was then responsible for Gulf of Mexico hurricane flights, had ordered most of its airplanes to fly to Puerto Rico to fly into another storm.

This storm was Hurricane Debby and the Navy airplanes were taking part in one of the big Stormfury cloud seeding experiments.

“The Navy had two old, decrepit planes” available, Simpson told us. Satellite images didn’t give him the accurate data he needed to estimate Camille’s strength. In fact, meteorologists in Washington who were analyzing the images told him Camille seemed to be weakening.

“I wasn’t sure the storm was losing intensity,” Simpson said. “I was convinced it was becoming close to a record storm just from the way the eye structure was changing.”

Simpson called the commander of the Air Force’s Air Weather Center at Scott Air Force Base in Illinois and told him what was at stake for both civilians and the military. The Air Force then sent a C-130 weather reconnaissance airplane, which reported winds of approximately 160 mph.

This report and a forecast by the Weather Bureau’s then-new storm surge model saying a 20-foot surge was possible, prompted Simpson’s strong warning, which helped prompt the evacuation of an estimated 81,000 of the 150,000 residents in the evacuation zone. The death toll on the Gulf Coast was put at 172 people.

The twist to the story: The flight into Debbie was considered the most successful test of the hypothesis that cloud seeding could weaken hurricanes, but scientists later learned that hurricanes such as Debbie go though natural cycles of growing weaker and stronger. Robert Simpson and Joanne Malkus originally proposed the hypothesis. They married in 1965. She died in 2010, he lives in the Washington area.