Alert archive / Iowa / Flash Flood Warnings in 2011

Flash Flood Warning 6, NWS Des Moines, IA

May 11, 2011Union County, Iowa

NWS Des Moines, IA issued this flash flood warning at May 11, 2011, 6:03 PM CDT for Union County, Iowa. It was in force for 6 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: May 11, 2011, 6:03 PM CDT (23:03 UTC)
Expired: May 12, 2011, 12:00 AM CDT
In force: 6 hr
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Flood severity: None

County Union County, IA

The radar

The Des Moines radar (KDMX), 93 km from the middle of the area, began a volume at 23:07 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
May 11, 6:15 PM CDT	FLASH FLOOD	3 Nne Creston Airport, IA	UNION COUNTY LAW ENFORCEMENT REPORTED THE OSAGE RAILROAD BRIDGE WAS IMPASSIBLE DUE TO WATER OVER THE ROAD. ONE CAR WAS STRANDED.

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

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.1 hours before the alert went out and 177 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: 909 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 1123 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 177 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

538 
WGUS53 KDMX 112303
FFWDMX
IAC175-120500-
/O.NEW.KDMX.FF.W.0006.110511T2303Z-110512T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
603 PM CDT WED MAY 11 2011

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  UNION COUNTY IN SOUTH CENTRAL IOWA...

* UNTIL MIDNIGHT CDT

* AT 602 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE   
  WARNED AREA. RAINFALL RATES OF 2 TO 3 INCHES PER HOUR CAN BE 
  EXPECTED OVER THE NEXT 1 TO 2 HOURS. 

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  CRESTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. TURN AROUND...DONT DROWN.

&&

LAT...LON 4090 9429 4090 9447 4116 9447 4116 9440
      4115 9440 4116 9401 4090 9402 4090 9428

$$

PODRAZIK

3 follow-up statements

083 
WGUS73 KDMX 112347
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
647 PM CDT WED MAY 11 2011

IAC175-120500-
/O.CON.KDMX.FF.W.0006.000000T0000Z-110512T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
UNION IA-
647 PM CDT WED MAY 11 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR UNION COUNTY UNTIL
MIDNIGHT CDT...

AT 644 PM CDT...LOCAL LAW ENFORCEMENT OFFICIALS REPORTED 
THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE WARNED AREA. THE 
HEAVY RAINFALL HAS COME TO AN END...HOWEVER RUNOFF WILL CONTINUE TO 
POSE A PROBLEM ACROSS NORTHERN PORTIONS OF THE COUNTY. 

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH  FLOODING INCLUDE...
CRESTON.

AT 615 PM CDT...UNION COUNTY LAW ENFORCEMENT REPORTED THE OSAGE 
RAILROAD BRIDGE WAS IMPASSIBLE DUE TO WATER COVERING THE ROAD. ONE 
CAR WAS STRANDED DUE TO THE HIGH WATER. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND THE
WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. TURN
AROUND...DONT DROWN.

&&

LAT...LON 4090 9429 4090 9447 4116 9447 4116 9440
      4115 9440 4116 9401 4090 9402 4090 9428

$$

PODRAZIK

706 
WGUS73 KDMX 120145
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
845 PM CDT WED MAY 11 2011

IAC175-120500-
/O.CON.KDMX.FF.W.0006.000000T0000Z-110512T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
UNION IA-
845 PM CDT WED MAY 11 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR UNION COUNTY UNTIL
MIDNIGHT CDT...

AT 838 PM CDT...FLOODING MAY STILL BE OCCURRING IN PORTIONS OF UNION 
COUNTY FROM HEAVY RAINFALL EARLIER THIS EVENING.  NATIONAL WEATHER 
SERVICE ADJUSTED DOPPLER RADAR ESTIMATES SHOW TWO TO FIVE INCHES OF 
RAIN MAY HAVE FALLEN ACROSS THE COUNTY IN THE PAST 12 HOURS WITH THE 
HEAVIEST RAINS BETWEEN CRESTON...SHANNON CITY...ARISPE AND AFTON.  
THE UNION COUNTY EMERGENCY MANAGER ALSO REPORTED FOUR INCHES OF RAIN 
HAD FALLEN SEVEN MILES SOUTH OF CRESTON.

SOME LOCATIONS THAT MAY EXPERIENCE FLASH FLOODING 
INCLUDE...CRESTON...SHANNON CITY...ARISPE AND AFTON AS WELL AS 
TWELVE MILE CREEK...THE WEST PLATTE RIVER AND OTHER SMALLER 
TRIBUTARIES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS... AS WELL AS FARMLAND ALONG THE
BANKS OF CREEKS AND STREAMS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLOODING IS OBSERVED...ACT QUICKLY. DO NOT
ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND. DO NOT
STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 4090 9429 4090 9447 4116 9447 4116 9440
      4115 9440 4116 9401 4090 9402 4090 9428

$$

SMALL

661 
WGUS73 KDMX 120502
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
1202 AM CDT THU MAY 12 2011

IAC175-120515-
/O.EXP.KDMX.FF.W.0006.000000T0000Z-110512T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
UNION IA-
1202 AM CDT THU MAY 12 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR UNION COUNTY HAS
BEEN ALLOWED TO EXPIRE...

EXCESS RUNOFF FROM PREVIOUS HEAVY RAIN HAS ENDED OVER THE WARNED 
AREA. STREAMS AND CREEKS HAVE RECEDED OR WERE BEGINNING TO 
RECEDE...ENDING THE IMMEDIATE FLOOD THREAT.  HOWEVER BRIEF HEAVY 
RAINS MAY STILL OCCUR OVERNIGHT RESULTING IN PONDING WATER ON 
ROADS...LOW VISIBILITIES...DITCHES REFILLING WITH WATER...AND 
ADDITIONAL MINOR RISES OF SMALL STREAMS AND CREEKS.

IF FLOODING HAS BEEN OBSERVED...PLEASE REPORT IT TO YOUR LOCAL LAW 
ENFORCEMENT AGENCY.

LAT...LON 4090 9429 4090 9447 4116 9447 4116 9440
      4115 9440 4116 9401 4090 9402 4090 9428

$$

SMALL

The office that day

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

Issued	Product	Office	Counties	Lasted
May 11, 12:43 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Cass	47 min
May 11, 2:05 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Taylor	55 min
May 11, 2:22 PM CDT	Tornado Warning	DMX	Adams	23 min
May 11, 2:43 PM CDT	Flash Flood Warning	DMX	Adams, Taylor	6 hr
May 11, 2:51 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Taylor	39 min
May 11, 4:01 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Taylor	44 min
May 11, 4:11 PM CDT	Tornado Warning	DMX	Adams, Taylor	49 min
May 11, 4:42 PM CDT	Flash Flood Warning	DMX	Adams, Taylor	6 hr
May 11, 4:50 PM CDT	Tornado Warning	DMX	Adams, Union	40 min
May 11, 4:57 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Taylor	38 min
May 11, 5:32 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Ringgold, Taylor, Union	43 min
May 11, 5:42 PM CDT	Tornado Warning	DMX	Union	33 min
May 11, 5:44 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Decatur, Lucas, Madison, Ringgold, Warren	46 min
May 11, 6:06 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Clarke, Madison, Union	54 min
May 11, 6:37 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	53 min
May 11, 6:42 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Decatur, Lucas, Warren	48 min
May 11, 6:46 PM CDT	Severe Thunderstorm Warning	DMX	Wayne	44 min

Nearby

Flash Flood Warnings in Iowa, 2011 Every flash flood warning in 2011

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.