Alert archive / South Dakota / Flash Flood Warnings in 2005

Flash Flood Warning 5, NWS Sioux Falls, SD

April 21, 2005Clay County, Union County, South Dakota

NWS Sioux Falls, SD issued this flash flood warning at Apr 21, 2005, 11:53 PM CDT for Clay County, Union County, South Dakota. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 21, 2005, 11:53 PM CDT (04:53 UTC)
Expired: Apr 22, 2005, 3:00 AM CDT
In force: 3 hr
Issued by: NWS Sioux Falls, SD
Area: Counties, with a storm outline in the text

Counties Clay County, SD, Union County, SD

The radar

The Sioux Falls radar (KFSD), 80 km from the middle of the area, began a volume at 04:52 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.9 hours before the alert went out and 177 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 396 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 608 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 205 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.8

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this flash flood warning went out at Apr 21, 9:30 PM CDT, 2 hours 23 minutes earlier.

Area forecast discussion, Apr 21, 9:30 PM CDT, 2 hours 23 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
930 PM CDT THU APR 21 2005

.DISCUSSION...
NEARLY STACKED LOW PRESSURE SYSTEM CENTERED JUST SOUTH OF THE CWA
NEAR KOFK.  THIS SYSTEM WILL GRADUALLY SLIDE TO THE SOUTHEAST
ALLOWING MUCH COOLER AND DRIER AIR TO WORK INTO REGION ON FRIDAY.
NICE BAND OF PRECIP CURRENTLY LOCATED BETWEEN K9V9 TO KFSD TO KSLB.
RAINFALL AMOUNTS ALONG SOUTHERN TIER OF COUNTIES IN SOUTH DAKOTA ARE
RUNNING BETWEEN 0.5 TO 0.75 INCHES...WHICH IS FAIRLY CLOSE TO FLASH
FLOOD GUIDANCE VALUES. WILL THEREFORE LEAVE THE FLOOD WATCH FOR
FLASH FLOODING GOING FOR NOW. DRY AIR ACROSS NORTHERN PORTION OF CWA
EATING AWAY ANY PRECIP ATTEMPTING TO SURGE NORTH.  HAVE THEREFORE
CUT POPS FURTHER NORTH NEAR KBKX AND KHON.  OTHERWISE...GOING
FORECAST IN GOOD SHAPE.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FLOOD WATCH SDZ050-063-068>071 4PM THU TO 6AM FRI.
MN...NONE.
IA...FLOOD WATCH IAZ020-031-032 4PM THU THRU 6AM FRI.
NE...FLOOD WATCH NEZ013-014 4PM THU THRU 6 AM FRI.

&&

BT

Hazardous weather outlook, Apr 21, 11:42 AM CDT, 12 hours 11 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1142 AM CDT THU APR 21 2005

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-221200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1142 AM CDT THU APR 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
SCATTERED SHOWERS WITH A FEW THUNDERSTORMS WILL CONTINUE OVER
MAINLY SOUTHEAST SOUTH DAKOTA THROUGH MID AFTERNOON. ADDITIONAL
THUNDERSTORM DEVELOPMENT WILL BECOME LIKELY THIS AFTERNOON AND
EVENING... ESPECIALLY THROUGH THE MISSOURI RIVER VALLEY. A FEW OF
THE STORMS THAT DEVELOP ALONG AND SOUTH OF A VERMILLION...TO
SIOUX CITY TO IDA GROVE LINE...COULD PRODUCE HAIL TO THE SIZE OF
QUARTERS.

FLOODING...
SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD THROUGH THE
MISSOURI VALLEY FROM LATE THIS AFTERNOON THROUGH TONIGHT. AN
ADDITIONAL INCH TO INCH AND A HALF OF RAINFALL POSSIBLE. COUPLED
WITH RAINFALL LAST NIGHT AND THIS MORNING...THIS AMOUNT OF
RAINFALL COULD PRODUCE SOME LOCALIZED FLASH FLOODING...AND SEND
SOME STREAMS AND CREEKS OUT OF THEIR BANKS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

STRONG LOW PRESSURE WILL MOVE THROUGH THURSDAY NIGHT...ALLOWING A
NORTH WIND TO DEVELOP. THIS WIND WILL BECOME FAIRLY STRONG ON
FRIDAY...WITH GUSTS OF 35 TO 40 MPH POSSIBLE IN MOST LOCATIONS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 4 PM FROM VERMILLION...
EAST THROUGH SIOUX CITY AND IDA GROVE.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.CRH.NOAA.GOV/FSD. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.

 JH

In the hours before

Local storm report, Apr 21, 10:50 PM CDT, 1 hour 3 minutes before

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The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 21, 10:16 PM CDT	Flash Flood Warning	FSD	Clay, Union	3 hr

Nearby

Flash Flood Warnings in South Dakota, 2005 Every flash flood warning in 2005

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.