1947 Project Cirrus Hurricane - Aftermath

Aftermath

In South Florida, the flooding from the September and October hurricanes led to the creation in 1949 of what is now the South Florida Water Management District, which under a Congressional plan was entrusted with the task of preventing a recurrence of significant flooding by forming an improved flood-control system to modulate the water table and by providing suitable water levels with which to water crops, prevent saltwater intrusion, and support recreational opportunities as well as the growing South Florida communities. Large pumping systems were constructed, along with numerous new levees and canals, to mitigate the risk of large-scale flooding, yet population growth since the late 1940s is believed to have reduced the extent of vacant lands needed for effective drainage, thereby increasing the risk of damage during a flood similar to that of 1947. In his 1974 book Beyond the Fourth Generation, former EDD Chief Engineer Lamar Johnson voiced his concerns about large-scale development near the levees, which separate the Everglades water conservation areas from the Miami metropolitan area. Johnson wrote, “It is my opinion...that anytime that area gets a foot or more of rainfall overnight, the shades of 1947’s flood will be with them again.”

The cyclone was historically significant in that it was the first tropical cyclone to be modified as part of a multi-year operation called Project Cirrus. In July 1946, General Electric (GE) scientists concluded after experimentation that dry ice seeding could induce heavy rainfall and thus ultimately weaken storms by cooling temperatures in the eye. To undertake Project Cirrus, GE, the United States Army, the Office of Naval Research, and the U.S. Weather Bureau functioned jointly on research and planning. Early on October 13, 1947, 200 pounds (3,200 oz) of dry ice were dropped throughout the storm, then located about 350 mi (560 km) east of Jacksonville, Florida. While the appearance of the clouds changed, the initial results of the seeding were inconclusive. Shortly after the seeding took place, the hurricane turned sharply toward the Southeastern United States. While the move the leading GE scientist later blamed upon the seeding, subsequent examination of the environment surrounding the storm determined that a large upper-level ridge was in fact responsible for the abrupt turn.

Following the phonetic alphabet from World War II, the U.S. Weather Bureau office in Miami, Florida, which then worked in conjunction with the military, named the storm King, though such names were apparently informal and did not appear in public advisories until 1950, when the first Atlantic storm to be so designated was Hurricane Fox.