336 IOWA DEPARTMENT OF AGRICULTURE' 



TORNADO OF MAY 9, 1918, PEARL ROCK TO CALMAR, IOWA. 



By Hal P. Hardin, Observer,, 



[Dated: Weather Bureau, Charles City, Iowa. May 25, 1918.] 



(75th meridian meantime used herein.) 

 A tornado passed east of this county, Floyd, during the afternoon 

 of May 9, 1918. The storm had some features which have made it difficult 

 to determine whether there was more than one tornado, or only one storm 

 that zigzagged over a strip 2 miles wide and 54 miles long. A straight line 

 through the middle of the zone showing wreckage runs due SW.-NE. and 

 encounters as many buildings and groves untouched as it does objects de- 

 stroyed, while the character of the wreckage at points a mile or less from 

 such a median line leaves no doubt that a tornado had visited them. 



The writer visited Pearl Rock during the afternoon of the following day, 

 i. e., May 10. There the width of the storm's path of destruction was about 

 200 yards, and could be defined as such for a distance of 2 miles from 

 southwest to northeast. There was no indication of a whirling wind out- 

 side that belt, nor for some distance at either end of it. A number of 

 persons who went through the storm at Pearl Rock and other points have 

 told me that they saw the funnel-shaped cloud, heard a roaring noise as 

 that of a rapidly moving railway train, and witnessed an inward and- 

 upward movement of objects toward it. 



Pleasant Valley. A man who observed the first known formation of the 

 funnel cloud at Lower Pleasant Valley, the point where the storm appar- 

 ently originated, described to me what he saw, as follows: The weather 

 had been warm, with thundershowers during much of the day. Shortly 

 before 4 p. m. two thunderstorm clouds moved rapidly from the west and 

 the east toward each other; there was vivid lightning with loud thunder, 

 and the heat became oppressive. There had been strong winds during the 

 day, but with the gathering of these clouds the wind ceased until there 

 was no surface air movement. Overhead the clouds seemed to be boiling; 

 in each bank light and dark clouds seemed to be trying to climb over one 

 another. The two banks met over a point about 1 mile northeast of where 

 the observer stood. There was less lightning and thunder than before; 

 the western cloud bank absorbed that bank which had come from the east, 

 all light shades disappeared, and the whole mass turned blue-black in 

 color. There was a roaring noise, and from the point where he judged the 

 lower edges of the clouds had met a downward bulge appeared and quickly 

 developed into the funnel. A twisting, gyral motion was seen in the 

 funnel, and he thought that he had noticed a revolving movement in the 

 whole bulging portion of the cloud, but was not sure of it as he had not 

 thought to look for it at the time. As the cloud started northeastward 

 heavy rain and light hail fell where the observer stood, followed by light 

 rain, high wind and cooler. This man was on an elevated piece of land, 

 and says he could plainly see the funnel for 4 miles, and that it moved 



