WEATHER .TING 



broad areas of cloud and precipita- 

 tion with measurable skill. At tirst, 

 the necessarily large volume of data 

 was processed manually; with the 

 arrival of electronic computers in the 

 mid-1950's, processing could be 

 completed in a few hours. 



This approach to research and pre- 

 diction caught the fancy of most 

 modern atmospheric scientists. Their 

 fascination with an objective system 

 that really worked — together with, 

 in a sense, a commitment to large, 

 expensive computer systems — has 

 brought into being a breed of sci- 

 entist different from those of pre- 

 Rossby days. This new approach has 

 strengths, but it also has weaknesses. 

 On the one hand, real progress has 

 been made in predicting for high- 

 altitude jet aircraft and even, hope- 

 fully, in forecasting large-scale at- 

 mospheric features several days 

 ahead of time. On the other hand, 

 de-emphasis of the Norwegian theory 

 has, if anything, degraded the mete- 

 orologist's ability to deal with the 

 small-scale atmospheric patterns as- 

 sociated with weather at or near the 

 earth's surface. 



The current approach has made 

 some inroads on the short-range, 

 small-area problem. In the past three 

 or four years, programs employing 

 closer grid networks and more at- 

 tention to the vertical variation of 

 low-level meteorological elements 

 have increased the detail of com- 

 puter-produced prognoses. In recent 

 tests, three-dimensional air-trajectory 

 computer programs have increased 

 the accuracy of forecasts of airfield 

 weather by a few percent in selected 

 geographic areas. 



Technological Contributions — 

 Most of the small increases in short- 

 period weather forecasts of the past 

 decade or so are not attributable to 

 the atmospheric sciences, however. 

 Thus, speeded-up communications 

 and computer-operations systems 

 have brought the "data-observation 

 time" closer to the "forecast time"; 



since short-period forecasts are more 

 accurate than long-period ones, an 

 improvement has been gained. Net- 

 works of observation stations have 

 gradually been augmented, benefi- 

 cially realigned, and provided with 

 improved instrumentation. New kinds 

 of data, such as those from weather 

 radar, have helped especially in very 

 short period forecasting (minutes to 

 hours) of clouds, precipitation, and 

 severe weather. Improved Air 

 Weather Service and other weather- 

 reconnaissance planes have strength- 

 ened the National Weather Service's 

 diagnostic capability; they have been 

 vital in pinpointing hurricane loca- 

 tions and specifying their intensities. 

 Judicious use of various stratifications 

 of past weather data (climatology), 

 again a technique requiring no mete- 

 orological skill in its applications, has 

 helped to reduce large errors in local 

 forecasts. There have also been ad- 

 vances in management practices, such 

 as grouping specialized meteorolo- 

 gists at locations where they can 

 work uninterrupted by telephonic or 

 face-to-face confrontations with their 

 public or military customers. 



Satellites — The meteorological sat- 

 ellite is the most significant innova- 

 tion in the atmospheric sciences since 

 the computer. By far its greatest 

 contribution to date has been to 

 provide the meteorologist with cloud- 

 cover information on a global basis. 

 Research on the use of infrared data 

 obtained by satellite is growing; these 

 data have real potential, but they 

 have not yet contributed to improve- 

 ment in routine short-period predic- 

 tion. 



The satellite has vastly increased 

 day-to-day knowledge of existing 

 cloud cover, which in turn has im- 

 proved subjectively derived circula- 

 tion patterns that embrace fronts, 

 major storm centers (including hurri- 

 canes), and other large-scale tropical 

 features, and even some of the larger 

 thunderstorms. It is sometimes feas- 

 ible to deduce upper-level winds 

 from observed cloud features. 



The satellites assist the lorecastcr 

 to make predictions for an is such 

 as the oceans and regions of the 

 southern hemisphere, where data can- 

 not be obtained by conventional 

 means. In special cases — e.g., in 

 overseas military operations and in 

 flights over regions of the United 

 States not covered by conventional 

 data-gathering systems — they can 

 be of much, occasionally vital, aid to 

 the weather forecaster. Without 

 rapid access to good-quality, recent 

 satellite read-outs, however, the value 

 of the data for short-period forecast- 

 ing drops quickly. 



It must be remembered that satel- 

 lites describe present conditions; the 

 atmospheric scientist is still con- 

 fronted with the classical problem of 

 predicting how conditions will change. 

 Furthermore, satellites do not meas- 

 ure parameters beneath the tops of 

 clouds (except for thin cirrus). 



Actions to Improve the 

 Value of Forecasts 



As noted earlier, an adequate data 

 base for evaluating weather forecast- 

 ing does not exist. A satisfactory 

 evaluation program also does not 

 exist with respect to the community 

 of atmospheric scientists. There are 

 sporadic evaluation programs, but 

 statistics for one kind of forecast do 

 not necessarily apply to other kinds 

 and proper assessments for long pe- 

 riods of years are not available. Fur- 

 ther, forecast-verification programs 

 are normally conducted by the agen- 

 cies that make the forecasts them- 

 selves, leaving open the question of 

 objectivity. 



Operational Data Transmission ■ — 

 Over data-sparse areas such as re- 

 mote oceanic regions, airlines and 

 other flying agencies are already test- 

 ing the use of rapid, automated trans- 

 mission of operational data via satel- 

 lite to management centers. Selected 

 meteorological data should be in- 

 cluded and made available to appro- 



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