Alert archive / Iowa / Flash Flood Warnings in 2021

Flash Flood Warning 5, NWS Sioux Falls, SD

August 28, 2021Dickinson County, Osceola County, Iowa; Cottonwood County, Jackson County, Minnesota

NWS Sioux Falls, SD issued this flash flood warning at Aug 28, 2021, 10:24 PM CDT for Dickinson County, Osceola County, Iowa; Cottonwood County, Jackson County, Minnesota. It was in force for 5 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 28, 2021, 10:24 PM CDT (03:24 UTC)
Expired
Aug 29, 2021, 3:15 AM CDT
In force
5 hr
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon
Flood severity
None

Counties Dickinson County, IA, Osceola County, IA, Cottonwood County, MN, Jackson County, MN

The radar

The Sioux Falls radar (KFSD), 123 km from the middle of the area, began a volume at 03:28 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

Minneapolis, MN (KMPX), launched 00:00Z, 3.4 hours before the alert went out and 191 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, Minneapolis, MN at 00:00Z on 2021-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1990 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2021-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 252 square meters per square second.19395878Sfc1 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
1990 J/kg
Mixed-layer CIN
-120 J/kg
Mixed-layer LCL
977 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
252 m²/s²
0-3 km storm-relative helicity
227 m²/s²
Significant tornado parameter
1.0
Supercell composite
5.0

Open this sounding in Storm Lab

The text

As transmitted.

240 
WGUS53 KFSD 290324
FFWFSD
IAC059-143-MNC033-063-290815-
/O.NEW.KFSD.FF.W.0005.210829T0324Z-210829T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Sioux Falls SD
1024 PM CDT Sat Aug 28 2021

The National Weather Service in Sioux Falls has issued a

* Flash Flood Warning for...
  Dickinson County in northwestern Iowa...
  Eastern Osceola County in northwestern Iowa...
  Southeastern Cottonwood County in southwestern Minnesota...
  Jackson County in southwestern Minnesota...

* Until 315 AM CDT.

* At 1024 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain are moving into the warned area. The expected rainfall 
  rate is 1 to 3 inches per hour. Flash flooding is expected to 
  begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Spirit Lake, Jackson In Jackson County, Milford, Lakefield, 
  Arnolds Park, Lake Park, Bergen, Okoboji, Heron Lake, Orleans, 
  Ocheyedan, Terril, Wahpeton, West Okoboji, Harris, Superior, Kilen 
  Woods State Park, Okabena, Alpha and Wilder.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4385 9545 4385 9485 4350 9485 4351 9492
      4327 9491 4330 9577 4350 9545

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-3 INCHES IN 1 HOUR

$$

Schumacher
2 follow-up statements
662 
WGUS73 KFSD 290424
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
1124 PM CDT Sat Aug 28 2021

IAC059-143-MNC033-063-290815-
/O.CON.KFSD.FF.W.0005.000000T0000Z-210829T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Dickinson IA-Osceola IA-Cottonwood MN-Jackson MN-
1124 PM CDT Sat Aug 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM CDT SUNDAY FOR 
DICKINSON, EASTERN OSCEOLA, SOUTHEASTERN COTTONWOOD AND JACKSON 
COUNTIES...

At 1124 PM CDT, Doppler radar indicated thunderstorms producing 
heavy rain across the warned area. Up to 2 inches of rain have 
fallen. The expected rainfall rate is 2 inches per hour. Additional 
rainfall amounts up to 2 inches are possible in the warned area with 
the heaviest rainfall expected across Dickinson County. Flash 
flooding is ongoing or expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Spirit Lake, Jackson In Jackson County, Milford, Lakefield, 
  Arnolds Park, Lake Park, Bergen, Okoboji, Heron Lake, Orleans, 
  Ocheyedan, Terril, Wahpeton, West Okoboji, Harris, Superior, Kilen 
  Woods State Park, Okabena, Alpha and Wilder.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4385 9545 4385 9485 4350 9485 4351 9492
      4327 9491 4330 9577 4350 9545

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2 INCHES IN 1 HOUR

$$

Schumacher
862 
WGUS73 KFSD 290806
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
306 AM CDT Sun Aug 29 2021

IAC059-143-MNC033-063-290816-
/O.EXP.KFSD.FF.W.0005.000000T0000Z-210829T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Dickinson IA-Osceola IA-Cottonwood MN-Jackson MN-
306 AM CDT Sun Aug 29 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 315 AM CDT EARLY THIS MORNING 
FOR DICKINSON, EASTERN OSCEOLA, SOUTHEASTERN COTTONWOOD AND JACKSON 
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4385 9545 4385 9485 4350 9485 4351 9492
      4327 9491 4330 9577 4350 9545

$$

SSC

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 28, 7:23 PM CDTSevere Thunderstorm Warning Considerable damage threatFSDLyon52 min
Aug 28, 8:52 PM CDTSevere Thunderstorm WarningFSDLyon, Osceola, Sioux23 min
Aug 28, 9:13 PM CDTSevere Thunderstorm WarningFSDDickinson, Lyon, O'Brien, Osceola, Sioux47 min
Aug 28, 9:29 PM CDTFlash Flood WarningFSDLyon3 hr
Aug 28, 10:04 PM CDTFlash Flood WarningFSDLyon, Osceola4 hr
Aug 28, 7:00 PM CDTSevere Thunderstorm Warning Considerable damage threatFSDLincoln, Lyon, Murray, Pipestone45 min
Aug 28, 7:34 PM CDTSevere Thunderstorm WarningFSDLyon, Murray, Pipestone56 min
Aug 28, 7:48 PM CDTSevere Thunderstorm WarningFSDRock31 min
Aug 28, 8:03 PM CDTFlash Flood WarningFSDMurray, Pipestone6 hr
Aug 28, 8:06 PM CDTSevere Thunderstorm Warning Considerable damage threatFSDNobles, Rock54 min
Aug 28, 8:17 PM CDTSevere Thunderstorm Warning Considerable damage threatFSDCottonwood, Lyon, Murray58 min

Nearby

Flash Flood Warnings in Iowa, 2021Flash Flood Warnings in Minnesota, 2021Every flash flood warning in 2021

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.