ABUS34 KFSD 011928 PNSFSD PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE SIOUX FALLS SD 230 PM CDT TUE JUN 1 2004 ...SKUNK CREEK IN SIOUX FALLS HITS HIGHEST STAGE IN 20 YEARS... THE HEAVY RAINFALL ACROSS THE SIOUX FALLS AND MINNEHAHA COUNTY AREA SATURDAY EVENING, MAY 29TH, PUSHED SKUNK CREEK IN SIOUX FALLS TO ITS HIGHEST LEVEL IN 20 YEARS. ACCORDING TO THE RIVER GAGE ON MARION ROAD, SKUNK CREEK CRESTED AT 12.69 FEET SUNDAY AFTERNOON, THE HIGHEST READING SINCE IT HIT 15.54 FEET ON JUNE 21, 1984. THIS RANKED AS THE 5TH HIGHEST STAGE SINCE THE GAGE WAS INSTALLED IN 1949, AND THE FLOW OF APPROXIMATELY 8600 CUBIC FEET PER SECOND (CFS) WAS THE 4TH HIGHEST ON RECORD. DATE STAGE (FT) FLOW (CFS) 6/17/1957 17.78 29,400 6/21/1984 15.54 11,000 3/30/1960 13.64 8,200 4/6/1969 13.24 9,710 5/30/2004 12.69 8,600 OFFICIALLY, AT THE SIOUX FALLS AIRPORT, 4.35 INCHES OF RAIN WAS RECORDED IN 24 HOURS FROM SATURDAY MORNING, MAY 29TH, THROUGH SUNDAY MORNING, MAY 30TH. IN 6 HOURS, BETWEEN 6 PM AND MIDNIGHT, 4.14 INCHES WAS RECORDED. THE GREATEST 3 HOUR TOTAL WAS 3.53 INCHES BETWEEN 7 PM AND 10 PM. ASSUMING AN AVERAGE RAINFALL OF 3 INCHES ACROSS MINNEHAHA COUNTY, A TOTAL OF APPROXIMATELY 42 BILLION GALLONS OF WATER FELL IN THIS COUNTY ALONE ON SATURDAY NIGHT. STATISTICALLY, THIS EVENT CAN BE CONSIDERED SOMEWHERE BETWEEN A 15 AND 50 YEAR EVENT. THAT MEANS THAT, STATISTICALLY, THERE IS BETWEEN A 2 PERCENT AND 7 PERCENT CHANCE OF AN EVENT OF THIS MAGNITUDE OCCURRING IN ANY GIVEN YEAR. HERE ARE SOME OF THE APPROXIMATE RECURRENCE INTERVALS FOR THIS EVENT: * STAGE/FLOW ON SKUNK CREEK OF 12.69 FT/8600 CFS = 15-20 YEAR (5-7%) * 3 HOUR RAINFALL OF 3.53 INCHES = 50 YEAR (2 PERCENT) * 6 HOUR RAINFALL OF 4.14 INCHES = 50 YEAR (2 PERCENT) * 12 HOUR RAINFALL OF 4.33 INCHES = 25 YEAR (4 PERCENT) * 24 HOUR RAINFALL OF 4.35 INCHES = 15 YEARS (7 PERCENT) $$ GILLISPIE |