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<br />...: ;: <br /> <br />I <br />I <br />I <br />! I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />! I <br />I <br />I <br />I <br /> <br />-~',,,,.__",-o,'.>_ . . <br /> <br />of August 23 are also notable for their extensive aerial coverage and intensity <br />compared to the other storms, <br /> <br />Table 4 <br /> <br />Comparison of rainfall characteristics of Buffalo Creek <br />storms <br /> <br />DATE (1996) <br /> <br />PEAK 1/2 SQ, MI.. <br />TOTAL RAINFALL <br /> <br />BASIN AVG. <br />RAINFALL <br /> <br />% OF BASIN <br />RECEIVING >1,00" <br />OF RAINFALL <br />o <br />..84%; <br />o <br />o <br />,+;;",30%;' <br />o <br /> <br />% OF BASIN <br />RECEIVING >0,50" <br />OF RAINFALL <br />o <br />94%'.' <br />.: _ - ;0-_w_-__,__~~__ <br />o <br />o <br />;; ,.;~t"l~ <br />o <br /> <br />% OF BASIN <br />RECEIVING >0,25" <br />OF RAINFALL <br />o <br />~~% <br />13% <br />22% <br />77% <br />15% <br /> <br />JUNE12 <br />JUL Y,12 <br />AUGUST 7 <br />AUGUST 8 <br />AUGUST 23 <br />SEPTEMBER <br />14 <br /> <br />0.10" <br />6.29" <br />0.36" <br />0.46" <br />.1. t5'~, <br />0.4 7" <br /> <br /> <br />0,03" <br />'2A3" <br />0.11 " <br />0,15" <br />0.74" <br />0,14" <br /> <br />Based on the comparison of rainfall characteristics of the storms, HMS <br />suggests that the following quantitative characteristics of the storms radar <br />signature could be used to assist in the issuance of flash flood warnings by the <br />National Weather Service: <br /> <br />1, When> 60 % of the basin will be covered by 5-level or greater radar <br />reflectivity capable of producing 0.50" of rain in 60 minutes or less <br /> <br />2. When> 30 % of the basin will be covered by S-Ievel or greater radar <br />reflectivity capable of producing 1.00" of rain in 60 minutes or less <br /> <br />The combination of the observed meteorological and radar conditions may <br />provide quantitative guidelines to the National Weather Service which will assist <br />in the issuance of flash flood watches and warnings in the basin, These <br />guidelines will have to be evaluated within the context of the results of basin <br />hydrological studies and the flexibility of NWS policy. The results of this study <br />are considered preliminary but should provide an active opportunity for further <br />discussion. <br /> <br />25 <br />