Alert archive / Iowa / Flash Flood Warnings in 2021

Flash Flood Warning 4, NWS Des Moines, IA

August 12, 2021Appanoose County, Davis County, Iowa

NWS Des Moines, IA issued this flash flood warning at Aug 12, 2021, 11:12 AM CDT for Appanoose County, Davis County, Iowa. It was in force for 3 hr. 1 report 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 12, 2021, 11:12 AM CDT (16:12 UTC)
Expired: Aug 12, 2021, 1:44 PM CDT
In force: 3 hr
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Flood severity: None

Counties Appanoose County, IA, Davis County, IA

The radar

The Des Moines radar (KDMX), 145 km from the middle of the area, began a volume at 16:15 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 12, 12:18 PM CDT	FLASH FLOOD	1 S Cincinnati, IA	DELAYED REPORT -- MULTIPLE AREAS FLOODING, INCLUDING HWY 5. WHERE 6 TO 7 INCHES OF RUNNING WATER WAS OVER THE ROAD. SEVERAL OTHER ROADS IMPASSIBLE AT THE TIME.

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 12:00Z, 4.2 hours before the alert went out and 204 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2463 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

352 
WGUS53 KDMX 121612
FFWDMX
IAC007-051-121915-
/O.NEW.KDMX.FF.W.0004.210812T1612Z-210812T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Des Moines IA
1112 AM CDT Thu Aug 12 2021

The National Weather Service in Des Moines has issued a

* Flash Flood Warning for...
  Southeastern Appanoose County in south central Iowa...
  Davis County in southeastern Iowa...

* Until 215 PM CDT.

* At 1112 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 5 inches of rain 
  have fallen. Additional rainfall amounts of 2 to 4 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...
  Centerville, Bloomfield, Lake Sundown, Moulton, Cincinnati, 
  Pulaski, Drakesville, Exline, Floris, Unionville, Udell, 
  Bloomfield Municipal Airport, Lake Wapello State Park and Sharon 
  Bluffs State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4059 9295 4075 9289 4090 9259 4090 9218
      4060 9218

FLASH FLOOD...RADAR INDICATED

$$

Martin

2 follow-up statements

846 
WGUS73 KDMX 121739
FFSDMX

Flash Flood Statement
National Weather Service Des Moines IA
1239 PM CDT Thu Aug 12 2021

IAC007-051-121915-
/O.CON.KDMX.FF.W.0004.000000T0000Z-210812T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Appanoose IA-Davis IA-
1239 PM CDT Thu Aug 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 215 PM CDT THIS 
AFTERNOON FOR SOUTHEASTERN APPANOOSE AND DAVIS COUNTIES...

At 1239 PM CDT, Doppler radar indicated thunderstorms producing 
heavy rain across the warned area. Between 2 and 5 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...
  Centerville, Bloomfield, Lake Sundown, Moulton, Cincinnati, 
  Pulaski, Drakesville, Exline, Floris, Unionville, Udell, 
  Bloomfield Municipal Airport, Lake Wapello State Park and Sharon 
  Bluffs State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4059 9295 4075 9289 4090 9259 4090 9218
      4060 9218

FLASH FLOOD...RADAR INDICATED

$$

Martin

778 
WGUS73 KDMX 121844
FFSDMX

Flash Flood Statement
National Weather Service Des Moines IA
144 PM CDT Thu Aug 12 2021

IAC007-051-121854-
/O.CAN.KDMX.FF.W.0004.000000T0000Z-210812T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Appanoose IA-Davis IA-
144 PM CDT Thu Aug 12 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHEASTERN APPANOOSE AND 
DAVIS COUNTIES...

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

A Flash Flood Watch remains in effect until 700 AM CDT Friday for 
portions of south central Iowa and southeast Iowa.

LAT...LON 4059 9295 4075 9289 4090 9259 4090 9218
      4060 9218

$$

Martin

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 12, 4:30 AM CDT	Special Weather Statement	DMX	Decatur	30 min
Aug 12, 4:58 AM CDT	Special Weather Statement	DMX	Decatur	47 min
Aug 12, 7:38 AM CDT	Special Weather Statement	DMX	Davis	52 min
Aug 12, 1:30 PM CDT	Flash Flood Watch	DMX	Appanoose, Davis	7 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.