Alert archive / Iowa / Flash Flood Warnings in 2021

Flash Flood Warning 11, NWS Quad Cities, IA

August 11, 2021Des Moines County, Lee County, Iowa; Clark County, Missouri; Hancock County, Henderson County, Illinois

NWS Quad Cities, IA issued this flash flood warning at Aug 11, 2021, 6:59 AM CDT for Des Moines County, Lee County, Iowa; Clark County, Missouri; Hancock County, Henderson County, Illinois. It was in force for 3 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 11, 2021, 6:59 AM CDT (11:59 UTC)
Expired: Aug 11, 2021, 9:49 AM CDT
In force: 3 hr
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Flood severity: None

Counties Des Moines County, IA, Lee County, IA, Hancock County, IL, Henderson County, IL, Clark County, MO

The radar

The Quad Cities radar (KDVN), 143 km from the middle of the area, began a volume at 12:00 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.

What was reported inside it

Time	Report	Where	Remark
Aug 11, 7:00 AM CDT	FLASH FLOOD	1 Ne West Burlington, IA	FIRE DEPARTMENT REPORTED WATER DEEP ENOUGH ON STREETS IN AREA OF MT PLEASANT STREET AND WEB BURLINGTON AVENUE THAT VEHICLES WERE DIVERTING.
Aug 11, 7:40 AM CDT	FLASH FLOOD	2 Nnw Burlington, IA	EMERGENCY MANAGEMENT RELAYED A REPORT OF HIGHWAY 61 IN BURLINGTON BEING IMPASSABLE AND 3 VEHICLES WERE STRANDED. TIME ESTIMATED.
Aug 11, 8:25 AM CDT	HEAVY RAIN 1.87	1 Nne Burlington Region, IA	HEAVY RAIN FROM THIS MORNING.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 12.0 hours before the alert went out and 148 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: 856 J/kg
Mixed-layer CIN: -155 J/kg
Mixed-layer LCL: 940 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 77 m²/s²
0-3 km storm-relative helicity: 160 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -1.4

Open this sounding in Storm Lab

The text

As transmitted.

101 
WGUS53 KDVN 111159
FFWDVN
IAC057-111-ILC067-071-MOC045-111500-
/O.NEW.KDVN.FF.W.0011.210811T1159Z-210811T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Quad Cities IA IL
659 AM CDT Wed Aug 11 2021

The National Weather Service in Quad Cities has issued a

* Flash Flood Warning for...
  Southern Des Moines County in southeastern Iowa...
  Lee County in southeastern Iowa...
  Northwestern Hancock County in west central Illinois...
  Southwestern Henderson County in west central Illinois...
  Central Clark County in northeastern Missouri...

* Until 1000 AM CDT.

* At 659 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. 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...
  Burlington, Fort Madison, Keokuk, Kahoka, Nauvoo, West Burlington, 
  West Point, Dallas City, Donnellson, Montrose, Wayland, 
  Middletown, Carman, Franklin, Gulf Port, New Boston, Niota, St. 
  Francisville, Denmark and Iowa Army Ammunition Plant.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4026 9182 4039 9188 4056 9171 4089 9124
      4089 9101 4070 9108 4069 9108 4039 9142
      4038 9143 4026 9181

FLASH FLOOD...RADAR INDICATED

$$

Ervin

2 follow-up statements

719 
WGUS73 KDVN 111248
FFSDVN

Flash Flood Statement
National Weather Service Quad Cities IA IL
748 AM CDT Wed Aug 11 2021

IAC057-111-ILC067-071-MOC045-111500-
/O.CON.KDVN.FF.W.0011.000000T0000Z-210811T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Des Moines IA-Lee IA-Hancock IL-Henderson IL-Clark MO-
748 AM CDT Wed Aug 11 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 10 AM CDT THIS 
MORNING FOR SOUTHERN DES MOINES, LEE, NORTHWESTERN HANCOCK, 
SOUTHWESTERN HENDERSON AND CENTRAL CLARK COUNTIES...

At 748 AM CDT, Emergency management reported flash flooding along 
Highway 61 near Burlington, Iowa. Between 2 and 3 inches of rain 
have fallen. Additional rainfall amounts of 1 to 2 inches are 
possible in the warned area. Flash flooding is ongoing or expected 
to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Emergency management reported.

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...
  Burlington, Fort Madison, Keokuk, Kahoka, Nauvoo, West Burlington, 
  West Point, Dallas City, Donnellson, Montrose, Wayland, 
  Middletown, Carman, Franklin, Gulf Port, New Boston, Niota, St. 
  Francisville, Denmark and Iowa Army Ammunition Plant.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4026 9182 4039 9188 4056 9171 4089 9124
      4089 9101 4070 9108 4069 9108 4039 9142
      4038 9143 4026 9181

FLASH FLOOD...OBSERVED

$$

Ervin

350 
WGUS73 KDVN 111449
FFSDVN

Flash Flood Statement
National Weather Service Quad Cities IA IL
949 AM CDT Wed Aug 11 2021

IAC057-111-ILC067-071-MOC045-111459-
/O.CAN.KDVN.FF.W.0011.000000T0000Z-210811T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Des Moines IA-Lee IA-Hancock IL-Henderson IL-Clark MO-
949 AM CDT Wed Aug 11 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN DES MOINES, LEE, 
NORTHWESTERN HANCOCK, SOUTHWESTERN HENDERSON AND CENTRAL CLARK 
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures. An areal 
flood warning will continue today for locations between Ft. Madison 
and Burlington due to the rain early this morning.

LAT...LON 4026 9182 4039 9188 4056 9171 4089 9124
      4089 9101 4070 9108 4069 9108 4039 9142
      4038 9143 4026 9181

$$

Ervin

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 5:38 AM CDT	Special Weather Statement	DVN	Lee	37 min
Aug 11, 5:56 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Lee	19 min
Aug 11, 6:10 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Lee	20 min
Aug 11, 6:24 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines	22 min
Aug 11, 6:38 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Louisa	37 min
Aug 11, 7:04 AM CDT	Special Weather Statement	DVN	Muscatine	26 min
Aug 11, 8:16 AM CDT	High Wind Warning	DVN	Clinton, Des Moines, Louisa, Muscatine, Scott	104 min
Aug 11, 9:46 AM CDT	Areal Flood Warning	DVN	Des Moines, Lee	3 hr
Aug 11, 10:24 AM CDT	Special Weather Statement	DVN	Lee	21 min
Aug 11, 3:36 PM CDT	Special Weather Statement	DVN	Washington	24 min
Aug 11, 4:26 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque	49 min
Aug 11, 5:11 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jackson, Jones	49 min
Aug 11, 5:38 PM CDT	Tornado Warning	DVN	Dubuque	13 min
Aug 11, 5:11 AM CDT	Special Weather Statement	DVN	Clark	34 min
Aug 11, 6:24 AM CDT	Special Weather Statement	DVN	McDonough	36 min
Aug 11, 7:32 AM CDT	Special Weather Statement	DVN	Rock Island	28 min
Aug 11, 7:55 AM CDT	Special Weather Statement	DVN	Bureau, Henry, Whiteside	65 min
Aug 11, 8:07 AM CDT	Severe Thunderstorm Warning	DVN	Bureau, Henry, Rock Island, Whiteside	53 min
Aug 11, 8:33 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Bureau, Putnam, Whiteside	57 min
Aug 11, 9:59 AM CDT	Special Weather Statement	DVN	McDonough	31 min
Aug 11, 10:45 AM CDT	Special Weather Statement	DVN	Henderson, Warren	30 min
Aug 11, 10:57 AM CDT	Severe Thunderstorm Warning	DVN	Henderson, McDonough, Warren	33 min

Nearby

Flash Flood Warnings in Iowa, 2021 Flash Flood Warnings in Illinois, 2021 Flash Flood Warnings in Missouri, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.