TORNADOES 



ciated rainstorms. In 17 cases, lumi- 

 nosity of an apparently electrical 

 origin was noted in the tornado fun- 

 nel itself, while in 49 cases the ab- 

 sence of any electrical indication in 

 the cloud was specifically reported. 

 More recently, interest in electrical 

 theories was stimulated when Jones 

 reported unusual 100-kHz radiation 

 from a tornadic storm. Vonnegut 

 presented an electrical theory of tor- 

 nadoes; Brook has reported on the 

 magnetic anomaly observed during 

 touchdown of a tornado near Tulsa; 

 and Weller and Waite have proposed 

 that tornadoes are associated with 

 intense electromagnetic radiation at 

 television frequencies. On the other 

 hand, Gunn measured the electrical 

 activity of the tornadic storm that 

 devastated Udall, Kansas, on May 25, 

 1955, and found it to be "more or 

 less typical of exceptionally active 

 storms." Rossow has measured mag- 

 netic fields over numerous water- 

 spouts and found little disturbance. 

 Kinzer and Morgan located the posi- 

 tion of sferics sources in the tornadic 

 storm in Oklahoma on June 10, 1967, 

 and reported no obvious connection 

 between areas of cloud lightning and 

 tornado locations. 



In a sense, the tornado itself is only 

 an important detail of the circulation 

 and energy balance of the larger 

 thunderstorm. By virtue of its larger 

 size and greater frequency, the typical 

 parent thunderstorm lends itself much 

 more to detailed examination. There- 

 fore, present research is concentrated 

 on identifying details in atmospheric 

 structure associated with formation 

 of tornadic and non-tornadic storms, 

 with the variable behavior of different 

 storms that form in the same general 

 area, and with the evaluation of the 

 way forces manifested in the storm 

 environment combine to produce ma- 

 jor features of the in-storm motions. 

 To this end, experimental networks 

 of closely spaced surface and upper 

 air stations are used along with quan- 

 titative radar and specially instru- 

 mented aircraft. 



We have learned that severe and 

 enduring tornadoes form near the 



small low-pressure areas associated 

 with the hook-shaped radar echo 

 marked by the arrow in Figure V-7. 

 Within the last decade the combina- 

 tion of observations and data gath- 

 ered by many sensors at one place 

 has taught a great deal about major 

 features of thunderstorm circulation 

 and, indeed, has revealed important 

 but hitherto unidentified distinct 

 storm classes. 



Mathematical Modeling — All 

 present-day mathematical models of 

 weather represent extreme simplifica- 

 tions of the natural phenomena. We 

 are still especially far from simulat- 

 ing realistically and in combination 

 the many factors associated with the 

 development of local storms. 



Most adequate for their purpose 

 are the models of atmospheric be- 



havior on the scale oi 

 culation and large weathe 

 In use at the National Mcteoro 

 Center in Washington, D. C, such 

 models predict the general patterns 

 of horizontal wind, moisture, and 

 vertical currents; they provide useful 

 guidance to the thunderstorm fore- 

 caster, who combines their indications 

 with his knowledge of the distribu- 

 tion of features specifically associated 

 with local storms — and with his 

 judgment — to forecast the probable 

 location of storms. Models that fore- 

 cast directly the parameters known 

 to be important to thunderstorm de- 

 velopment are just beginning to come 

 into operational use. Some incorpo- 

 rate both dynamical and statistical 

 methodology and provide somewhat 

 more detailed spatial distributions 

 over the United States than has been 

 available heretofore. 



Figure V-7 — RADAR VIEW OF A HOOKED ECHO 



The picture is of a Plan Position Indicator (PPI) presentation of a severe storm over 

 Oklahoma City on May 26, 1963. Range marks denote intervals of 20 nautical miles. 

 North is toward the top. The radar is located at the center of the range circles. 

 The arrow points out the location of the tornado. 



139 



