Skunk Creek Flooding in Spring 2004

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