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<br />Oct-29-9S 10:50 HENZ METEOROLOGICAL SRVC. 303-458-5309 <br /> <br />P.03 <br /> <br />I. <br /> <br />page two <br /> <br />Table 1 shows an example of the rainfall data as prepared recently for the USGS <br />after the Virginia Canyon Flash Flood of August 18, 1991. HMS will prepare <br />spreadsheets of the rainfall and radar data coverage for basin areas in Excel 7.0 <br />for Windows 95 format on 1.44MB, 3.5 inch floppy disks for each of the events. <br /> <br />The time periods of rainfall re-constitution for each of the six events will use the <br />following identified archived radar data: <br /> <br />1. June 12: 1212216Z to 13/0112Z...Intense pre-flood thunderstorms <br />2. July 12: 12/1917Z to 13/0047Z... the antecedent moisture storm periods <br />3. July 12: 13/0053Z to 0533Z....the flash flooding storm period <br />4. August 7/8: 7/1938Z to 7/2043Z and 8/2055Z to 8/2224Z: two consecutive <br />days of intense storms over portions of the basins <br />5. August 23: 2001Z to 2309Z...post flood intense thunderstorms <br />6. September 14: 2105Z to 230SZ...intense post-flood thunderstorms <br /> <br />. <br /> <br />The time periods above are indicated in Z or GMT ( Greenwich Mean Time). <br />The relationship of local time to Z time is plus six hours, i.e., 1500 LDT or <br />3:00PM in the afternoon equates to 2100Z. Please note that HMS will be re- <br />constituting rainfall for all of the above time period for each of the events. <br /> <br />The re-constitution of the flash flood rainfall and the other events will prOVide <br />insight into the following concerns: <br /> <br />1. The rainfall mapping will provide a clear picture of the depth, aerial <br />coverage, intensity and duration of the rainfall that created the flash <br />flood on July 12, 1996 <br /> <br />2. The re-eonstituted rainfall information can be used to establish <br />quantitative rainfall criteria for the Issuance of flash flood watch and <br />warnings for the Buffalo Creek basin during its recovery period, <br /> <br />3. A clearer picture will emerge on the role of antecedent moisture in <br />producing the flash flood <br /> <br />4. Finally a contribution will be made to understanding the role of the <br />forest fjre on altering the local runoff characteristics of the basin. <br /> <br />. <br />