BULLETIN – EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
939 PM CDT MON JUN 20 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* FLASH FLOOD WARNING FOR…
LINCOLN COUNTY IN SOUTHEAST SOUTH DAKOTA
MINNEHAHA COUNTY IN SOUTHEAST SOUTH DAKOTA
NORTHEASTERN TURNER COUNTY IN SOUTHEAST SOUTH DAKOTA
NORTHWESTERN SIOUX COUNTY IN NORTHWEST IOWA
WESTERN LYON COUNTY IN NORTHWEST IOWA

* UNTIL 1230 AM CDT

* AT 934 PM CDT…NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH VERY HEAVY RAINFALL MOVING ACROSS THE WARNED
AREA. VERY HEAVY RAINFALL AMOUNTS OF 1 TO 2 INCHES IN LESS THAN AN
HOUR HAVE BEEN REPORTED WITH THIS LINE OF STORMS.
FURTHERMORE…THE LINE OF STORMS AFFECTING THE BIG SIOUX RIVER
VALLEY IS ELONGATED IN A NORTH TO SOUTH DIRECTION ALONG I 29…AND
ARE MOVING NORTHWARD. THIS MEANS THE RAINFALL COULD LAST OVER AN
HOUR IN SOME LOCATIONS…PRODUCING 2 TO 4 INCHES OF RAIN. URBAN
FLOODING IN LOW LYING AND POOR DRAINAGE AREAS WILL BE A SERIOUS
THREAT.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE…
CANTON…SIOUX FALLS…BALTIC…BRANDON…CHANCELLOR…COLTON…
CROOKS…FAIRVIEW…HARRISBURG…HARTFORD…LENNOX…NEWTON HILLS
STATE PARK…ROWENA…TEA…WALL LAKE AND WORTHING.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS…URBAN AREAS…HIGHWAYS…STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.