Alert archive / Iowa / Flash Flood Warnings in 2021

Flash Flood Warning 16, NWS Quad Cities, IA

August 26, 2021Keokuk County, Iowa

NWS Quad Cities, IA issued this flash flood warning at Aug 26, 2021, 10:29 PM CDT for Keokuk County, Iowa. It was in force for 4 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 26, 2021, 10:29 PM CDT (03:29 UTC)
Expired: Aug 27, 2021, 2:17 AM CDT
In force: 4 hr
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Flood severity: None

County Keokuk County, IA

The radar

The Des Moines radar (KDMX), 131 km from the middle of the area, began a volume at 03:29 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

Davenport, (KDVN), launched 00:00Z, 3.5 hours before the alert went out and 146 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: 673 J/kg
Mixed-layer CIN: -189 J/kg
Mixed-layer LCL: 1469 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: -106 m²/s²
0-3 km storm-relative helicity: -64 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -1.7

Open this sounding in Storm Lab

The text

As transmitted.

760 
WGUS53 KDVN 270329
FFWDVN
IAC107-270930-
/O.NEW.KDVN.FF.W.0016.210827T0329Z-210827T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Quad Cities IA IL
1029 PM CDT Thu Aug 26 2021

The National Weather Service in Quad Cities has issued a

* Flash Flood Warning for...
  Keokuk County in southeastern Iowa...

* Until 430 AM CDT Friday.

* At 1029 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 3 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly. This slow moving thunderstorm is producing 
  incredibly heavy rain.

  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...
  Sigourney, Hedrick, What Cheer, Delta, Keswick, Martinsburg, 
  Hayesville, Ollie, Webster, Thornburg, Gibson, Yenruogis County 
  Park, Keokuk County Expo, Lancaster, Lake Belva Deer Park, Keokuk 
  County Fairgrounds, Coal Creek and Pekin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4151 9211 4116 9208 4116 9241 4151 9241

FLASH FLOOD...RADAR INDICATED

$$

Ervin

2 follow-up statements

108 
WGUS73 KDVN 270544
FFSDVN

Flash Flood Statement
National Weather Service Quad Cities IA IL
1244 AM CDT Fri Aug 27 2021

IAC107-270930-
/O.CON.KDVN.FF.W.0016.000000T0000Z-210827T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Keokuk IA-
1244 AM CDT Fri Aug 27 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 430 AM CDT EARLY THIS 
MORNING FOR KEOKUK COUNTY...

At 1244 AM CDT, Doppler radar indicated thunderstorms producing 
heavy rain have ended cross the warned area. Between 3 and 4 inches 
of rain have fallen. Flash flooding is likely ongoing where this 
powerful storm slowly tracked.

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...
  Sigourney, Hedrick, What Cheer, Delta, Keswick, Martinsburg, 
  Hayesville, Ollie, Webster, Thornburg, Gibson, Yenruogis County 
  Park, Keokuk County Expo, Lancaster, Lake Belva Deer Park, Keokuk 
  County Fairgrounds, Coal Creek and Pekin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 4151 9211 4116 9208 4116 9241 4151 9241

FLASH FLOOD...RADAR INDICATED

$$

Ervin

038 
WGUS73 KDVN 270717
FFSDVN

Flash Flood Statement
National Weather Service Quad Cities IA IL
217 AM CDT Fri Aug 27 2021

IAC107-270727-
/O.CAN.KDVN.FF.W.0016.000000T0000Z-210827T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Keokuk IA-
217 AM CDT Fri Aug 27 2021

...FLASH FLOOD WARNING IS CANCELLED FOR KEOKUK COUNTY...

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

LAT...LON 4151 9211 4116 9208 4116 9211 4116 9212
      4116 9214 4116 9218 4116 9219 4116 9224
      4116 9225 4116 9235 4116 9237 4116 9241
      4151 9241 4151 9230 4151 9224 4151 9220
      4151 9218

$$

Ervin

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 26, 8:23 PM CDT	Special Weather Statement	DVN	Benton	52 min
Aug 26, 9:21 PM CDT	Severe Thunderstorm Warning	DVN	Iowa, Keokuk	39 min
Aug 26, 9:58 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Keokuk	47 min
Aug 26, 10:43 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Keokuk, Washington	47 min
Aug 26, 10:57 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Jefferson, Washington	48 min
Aug 26, 11:20 PM CDT	Tornado Warning	DVN	Jefferson, Keokuk	27 min
Aug 26, 11:39 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Jefferson, Washington	31 min
Aug 27, 1:34 PM CDT	Heat Advisory	DVN	Lee	29 hr
Aug 27, 3:07 PM CDT	Heat Advisory	DVN	Des Moines, Henry, Van Buren	28 hr

Nearby

Flash Flood Warnings in Iowa, 2021 Every 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.