Alert archive / Iowa / Flash Flood Watches in 2007

Flash Flood Watch 6, NWS Sioux Falls, SD

August 20, 200710 counties in Iowa; 6 counties in Minnesota

NWS Sioux Falls, SD issued this flash flood watch at Aug 20, 2007, 3:48 AM CDT for 10 counties in Iowa; 6 counties in Minnesota. It took effect at Aug 20, 2007, 1:00 PM CDT. It was in force for 11 hr.

The area

The counties it named.

The facts

Issued
Aug 20, 2007, 3:48 AM CDT (08:48 UTC)
In effect from
Aug 20, 2007, 1:00 PM CDT
Expired
Aug 20, 2007, 11:45 PM CDT
In force
11 hr
Issued by
NWS Sioux Falls, SD
Flood severity
None

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Ida County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN

The radar

The Sioux Falls radar (KFSD), 93 km from the middle of the area, began a volume at 08:49 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, 8.8 hours before the alert went out and 231 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-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2007-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2841 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2007-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2841 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
965 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
115 m²/s²
Significant tornado parameter
0.6
Supercell composite
3.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 watch went out at Aug 19, 11:45 PM CDT, 4 hours 3 minutes earlier.

Area forecast discussion, Aug 19, 11:45 PM CDT, 4 hours 3 minutes before
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Hazardous weather outlook, Aug 19, 10:43 PM CDT, 5 hours 5 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1043 PM CDT SUN AUG 19 2007

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-201200-
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-
1043 PM CDT SUN AUG 19 2007

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
SCATTERED THUNDERSTORMS WILL CONTINUE ACROSS NORTHWEST IOWA AND
SOUTHWEST MINNESOTA THIS EVENING AND INTO THE OVERNIGHT HOURS.
THESE STORMS ARE NOT EXPECTED TO BECOME SEVERE...HOWEVER HEAVY
RAIN IS LIKELY WITH SOME STORMS...WITH LOCALIZE FLASH FLOODING
POSSIBLE.

AN AREA OF THUNDERSTORMS OVER WESTERN SOUTH DAKOTA THIS
EVENING...WILL MOVE ACROSS THE STATE DURING THE OVERNIGHT HOURS.
THESE STORMS ARE NOT EXPECTED TO BE SEVERE.

FLOODING...
SCATTERED THUNDERSTORMS THIS EVENING WILL BE CAPABLE OF PRODUCING
VERY HEAVY RAIN...WITH RAINFALL RATES OF 1 TO 2 INCHES PER HOUR.
LOCALIZED FLASH FLOODING WILL BE POSSIBLE WITH STRONGER
THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SCATTERED THUNDERSTORMS ARE POSSIBLE OVER MUCH OF THE TRISTATE
AREA MONDAY MORNING...MOST OF WHICH ARE NOT EXPECTED TO BECOME
SEVERE. HOWEVER...THERE IS A CHANCE OF SEVERE STORMS MONDAY
AFTERNOON.  A MORE ORGANIZED AREA OF THUNDERSTORMS IS LIKELY TO
DEVELOP TUESDAY AFTERNOON OVER FAR SOUTHEAST SOUTH DAKOTA AND
SOUTHWEST MINNESOTA...PRESSING THROUGH NORTHWEST IOWA BY EARLY
EVENING. THESE STORMS WOULD HAVE A HIGHER POTENTIAL FOR MORE
WIDESPREAD SEVERE WEATHER...WITH THE THREAT FOR SOMEWHAT LARGER
HAIL AND STRONGER WINDS THAN MONDAY...AS WELL AS THE THREAT FOR A
FEW TORNADOES ACROSS NORTHWEST IOWA...EXTREME NORTHEAST NEBRASKA
AND FAR SOUTHEAST SOUTH DAKOTA.

MORE THUNDERSTORMS WILL AFFECT THE AREA LATER IN THE
WEEK...FOCUSING MAINLY ON THE NIGHTTIME INTO EARLY MORNING HOURS.
WHILE SOME THREAT FOR SEVERE STORMS WILL EXIST...HEAVY RAINFALL
WILL ALSO BE A THREAT...ESPECIALLY FROM THE LOWER MISSOURI VALLEY
THROUGH NORTHWEST IOWA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT LIKELY TONIGHT.
&&

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

LIEBL

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 5:48 AM CDTSevere Thunderstorm WarningFSDGregory27 min
Aug 20, 6:08 AM CDTSevere Thunderstorm WarningFSDGregory26 min
Aug 20, 9:02 AM CDTSevere Thunderstorm WarningFSDPlymouth28 min
Aug 20, 9:12 AM CDTSevere Thunderstorm WarningFSDCherokee, O'Brien, Sioux48 min
Aug 20, 9:46 AM CDTSevere Thunderstorm WarningFSDBuena Vista29 min
Aug 20, 10:15 AM CDTSevere Thunderstorm WarningFSDBuena Vista30 min
Aug 20, 3:01 PM CDTRiver Flood WarningFSDClay, Dickinson67 hr
Aug 20, 3:01 PM CDTRiver Flood WarningFSDBuena Vista7 days
Aug 20, 9:04 AM CDTSevere Thunderstorm WarningFSDJackson26 min

Nearby

Flash Flood Watches in Iowa, 2007Flash Flood Watches in Minnesota, 2007Every flash flood watch in 2007

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.