Project Stormfury - Failure of The Working Hypothesis

Failure of The Working Hypothesis

Multiple eyewalls had been detected in very strong hurricanes before, including Typhoon Sarah and Hurricane Donna, although the double eyes were usually seen in very intense systems. Double eyewalls were also seen post-seeding in some of the seeded storms. At the time however, the only known times that rapid changes in eyewall diameter, other than during presumably successful seedings, was during rapid changes in intensity. It remained controversial whether the seedings caused the secondary eyewalls or whether it was just a natural cycle. Basically, if eyewall changes similar to those observed in seeded hurricanes were rare in unseeded tropical cyclones, it would provide powerful evidence that Project Stormfury was successful. Conversely, if such changes were common in unseeded systems, it would throw doubt on the very hypothesis and assumptions driving Project Stormfury.

Data and observations began to accumulate that debunked Stormfury's working hypothesis. Beginning with Hurricanes Anita and David, flights by Hurricane Hunter aircraft encountered events similar to what happened in "successfully" seeded storms. Anita itself had a weak example of a concentric eyewall cycle, and David a more dramatic one. In August 1980, Hurricane Allen passed through the Atlantic, Caribbean, and Gulf of Mexico. It also underwent changes in the diameter of its eye and developed multiple eyewalls. All this was consistent with the behavior that would have been expected of Allen had it been seeded. Thus, what Stormfury was accomplishing by seeding was also happening on its own.

Other observations in Hurricanes Anita, David, Frederic, and Allen also discovered that tropical cyclones have very little supercooled water and a great deal of ice crystals. The reason that tropical cyclones have little supercooled water is that the updrafts within such a system are too weak to prevent water from either falling as rain or freezing. As cloud seeding needed supercooled water to function, the lack of supercooled water meant that seeding would have no effect.

Those observations called the basis for Project Stormfury into question. In the middle of 1983, Stormfury was finally canceled after the hypothesis guiding its efforts was invalidated.