Thunderstorm Phenomena and Weather Radar Scanning Strategies

Examination of several thunderstorms cell's maximum reflectivity and updraft spe ed shows that growth rates of maximum reflectivity factor ranged from 4 to 7 dBZ/min and those of maximum updraft speed ranged from 3 to 7 m/s/min. Times of occurrence of maximum values of reflectivity, storm height, and updraft speed are compared. The Air Force Geophysics Laboratory's storm analysis and tracking algorithms are used to evaluate interlaced and contiguous (non-interlaced) scanning strategies. Eleven cell attributes are determined and compared for each strategy. The differences between attribute values obtained from successive contiguous scans are about the same as the differences between values obtained from interlaced and contiguous scans for the same time period. Thus, an interlaced scanning strategy may allow detection of some hazards (e.g., low altitude shear in one-half the time expected using the proposed NEXRAD contiguous scanning strategy without significantly compromising the evaluation of storm attributes. Although these findings are incomplete because of small data sample they suggest that the NEXRAD doppler radar can provide more timely warnings of low altitude weather hazards in the terminal area if an interlaced scan strategy is used.