VIII - HURRICANES AND FOREST FIRES 



In addition to the normal studies and tests with which Project Cirrus 

 concerned itself, there were two additional activities in which it engaged 

 early in its history. One was a study of tropical hurricanes and the other, 

 an attempt to cause rain in a forest-fire area. Both took place in 1947. 



HURRICANE STUDY 



The hurricane study was planned by the various participating govern- 

 ment agencies for the purpose of determining whether seeding operations 

 could be carried out in such storms. These agencies hoped that the exper- 

 ience thus gained would permit the planning of further operations in the 

 future, with the hope of possibly steering or in other ways modifying trop- 

 ical hurricanes. 



It was planned to study a "young" storm as soon as possible after 

 it had assumed the form of a hurricane. A group of General Electric per- 

 sonnel was requested to act as consultants on these operations by the 

 chairman of the project's Operations Committee. 



After a week of intensive organization and briefing, both groups were 

 maintained in "stand-by" position, but the season progressed for some time 

 without any suitable storms occurring. Finally on October 10, 1947 word was 

 flashed from Miami, Florida, that a storm was forming below Swan Island 

 in the Caribbean Sea. 



Plans were immediately activated, and the next evening the project's 

 two B-17's were at Mobile, Alabama. The storm had traveled with such high 

 speed, however, that by that time it was crossing Florida. The unit flew 

 to MacDill Field, Florida the next day, joining forces with the 53rd Weather 

 Reconnaissance group. Plans were laid for take-off early in the morning " 

 of October 13. The storm was expected to be from 300 to 400 miles east 

 of Florida by that time. 



The following account of the observed features of the storm, the seed- 

 ing operation, and observed effects was prepared by Lt.Com. Daniel F. Rex, 

 at that time chairman of the Operations G roups (^ 



"The storm consisted of an eye approximately 30 miles 

 in diameter, surrounded by a thick wall of clouds extending 

 from about 800 feet up into the cirrus overcast at 20,000 feet 

 and being some 30-50 miles thick radially. Several decks (4 

 or 5) of stratified shelf clouds extended out from the outer wall, 

 the upper -most deck having tops at 10,000 feet. These shelf 

 clouds appeared as large areas (100-200 square miles) of solid, 

 thin (1000-2000 feet thick) undercast, separated by large breaks 

 through which the surface was often visible. An exceedingly 



