\DOES 



needs to be assessed. Although some 

 meteorological doppler radars are 

 presently in use and other systems 

 are under development, the pace of 

 work seems slow. 



The second emerging technique is 

 satellite infrared spectrometry, which 

 is providing new detail on the vertical 

 thermal stratification of the atmos- 

 phere at intervals of about 30 miles. 

 Further development of the satellite 

 system should result in better analy- 

 sis of severe thunderstorm precursor 

 conditions over the United States and 

 refinement of our forecasting ability. 



Computers — With regard to 

 mathematical modeling, greater real- 

 ism will be possible as computers 

 become larger and faster and as theo- 

 retical models are revised in light of 

 observations and experimental re- 

 sults. Of course, many techni-socio- 

 logical forces are already encouraging 

 the development of improved com- 

 puters. We may emphasize here that 

 no conceivable computer can ever 

 solve meteorological problems in such 

 a way that careful scientists will 

 not be an essential part of problem 

 preparation; indeed, theoretical in- 

 terpretation of data from observa- 

 tional and experimental programs 

 will be increasingly required to de- 

 velop reasonably posed mathematical 

 formulations. 



Physical Models — With regard to 

 physical modeling of thunderstorms 

 and tornadoes, the difficulties inher- 

 ent in modeling significant atmos- 

 pheric processes such as condensa- 

 tion and precipitation, in diminishing 

 the effect of container sidewalls to 

 levels consistent with the atmos- 

 phere's lack of sidewalls, and in 

 simulating the vertical density gra- 

 dient and diffusion processes charac- 

 teristic of the atmosphere will con- 

 tinue to represent serious obstacles. 

 These problems have been less seri- 

 ous with respect to interpretation of 

 the more essentially two-dimensional 

 flows representative of atmospheric 

 circulations on larger scales. Never- 

 theless, experimental methods should 



continue to be important for testing 

 tornado hypotheses and suggesting 

 new lines for observational and theo- 

 retical study. 



The General Status of the 

 Operational System for Severe 

 Storm Prediction and Warning 



Present-day severe-storm forecasts 

 are immensely valuable, but we wish 

 they were more precise and more ac- 

 curate. Although numerical methods 

 have been used for forecasting large- 

 scale weather patterns for over ten 

 years, the development of mathemati- 

 cal models relevant to the smaller 

 scale of local storm complexes is still 

 in its infancy. Basic improvements 

 in the quality of severe-storm fore- 

 casts depend on the development of 

 new understanding of storm struc- 

 ture and dynamics, the interaction 

 between severe local storms, and 

 the larger patterns of air motion 

 that establish the general conditions 

 favorable for storm development. As 

 previously indicated, such improved 

 understanding can be expected to 

 evolve only as the insights provided 

 by more detailed observations are 

 assessed by careful scientists with the 

 aid of more powerful computers. 

 Eventually, methods will be devel- 

 oped combining such detailed data as 

 that provided by radar and satellites 

 with other weather parameters in 

 dynamical storm models; appropriate 

 ways to use such detail in operational 

 forecast preparation should then be- 

 come clear. 



At present, we can strive to hasten 

 the preparation and distribution of 

 such forecasts as we have. To this 

 end, hand analysis of patterns signifi- 

 cant to local storm development is 

 being significantly replaced by com- 

 puter techniques. The radar network, 

 which is the backbone of the system 

 used for severe-storm warning, also 

 lends itself to significantly advanced 

 automation. Displays like that shown 

 in Figure V-7 can be replaced by 

 contour-mapped echo representa- 

 tions. (See Figure V-8) A correspond- 



ing digital array can be pro< 

 simultaneously (see Figure V 9) as a 

 basis for automatic preparation and 

 dissemination of extrapolation fore- 

 casts. In midwestern United States, 

 the Weather Service is presently 

 starting to develop an operational 

 test of advanced radar systems in 

 order to evaluate the probable costs 

 and benefits of various system de- 

 signs for nationwide application. 



Prospects for a Measure of 

 Tornado Control 



The energy production involved in 

 one severe local storm is comparable 

 to the total power-generating capacity 

 of the United States. Thus, the 

 control of severe-storm phenomena 

 clearly requires an ability to direct 

 far greater amounts of energy than 

 those locally applied by man at pres- 

 ent. This will depend on developing 

 knowledge of how to modify the 

 processes by which nature's supply is 

 utilized. For example, silver iodide 

 and a few other chemicals are used to 

 stimulate the freezing of water drops 

 that otherwise remain liquid during 

 cooling to temperatures somewhat 

 below their melting point; the arti- 

 ficial release of the latent heat of 

 fusion thus achieved can raise the air 

 temperature enough to enhance sig- 

 nificantly the growth of some clouds 

 and to hasten the dissipation of 

 others. Conceivably, this kind of 

 process could be applied to alter na- 

 ture's choice for rapid growth among 

 a host of nearly identical clouds. 



Other means for modifying torna- 

 does might involve alteration of the 

 earth's topography and roughness to 

 decrease the probability of tornadoes 

 over inhabited areas, and the direct 

 application of heat at a point in time 

 and place where such application 

 would beneficially modify the course 

 of subsequent events. It must be 

 plain from the foregoing discussion, 

 however, that we are still very far 

 from having a reasonable basis even 

 for estimating the likelihood that such 

 efforts could ever be successful. 



141 



