Iowa, 2001

Flooding in Iowa, May 11 to 14, 2001

May 11 to 14, 2001 · NWS DMX · 8 events in 8 counties and zones

Rainfall developed along a trough over western Iowa on the evening of the 9th and scattered showers dropped southeast across the HSA increasing in areal coverage over southern Iowa. Radar rainfall estimates of 3 to 4 inches prompted the issuance of a Small Stream Flood Advisory for Adams County.

Where it happened

Every event with a place to put it; 8 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
0
Property damage
$200,000
Crop damage
None recorded
Events
8

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS DMX wrote it up.

Rainfall developed along a trough over western Iowa on the evening of the 9th and scattered showers dropped southeast across the HSA increasing in areal coverage over southern Iowa. Radar rainfall estimates of 3 to 4 inches prompted the issuance of a Small Stream Flood Advisory for Adams County. Post-analysis showed these estimates were probably high by a factor of 1.5 to 2, as Corning measured only 2.12" near the center of the 3 to 4 inch radar estimate. Ottumwa measured 2.80", while, Beaconsfield, Blockton and Lamoni all received over 1 inch of rainfall. Minor flooding resulted due to already saturated soil conditions, but the flooding was largely agricultural.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before the first event at May 11, 1:59 AM CST, 4 hours 1 minute earlier.

Area forecast discussion, May 11, 1:59 AM CST, 4 hours 1 minute before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
259 AM CDT FRI MAY 11 2001

MAIN FCST QUESTIONS POSSIBLE PCPN TDA...AND HOW TO DEAL WITH PCPN
CHCS LATE SAT INTO EARLY NEXT WEEK.  07Z SFC ANLYS PLACES SLOW MOVG
CDFNT FM NERN KS INTO FA INVOF KOTM AND THEN INTO WI.  SHWRS/TSTMS
CONT TO LINGER IN SE SO WL BREAK OFF SERN SXN PER CURRENT RADAR
TRENDS TWRD ISSUANCE TIME.  OTHER PCPN CHCS THIS MRNG ASSOCD WITH
SHRT WV OVR ERN DAKOTAS AND MN.  MDLS ALL RECOGNIZE THIS FEATURE BUT
MAY BE A BIT SLOW PER STLT IMAGERY.  QG FORCING NIL TDA.  SOME
DIFFERENTIAL PVA NOTED BUT IS LIKELY BEING OFFSET BY COLD ADVCTN.
AMS DRYS OUT UPSTREAM WITH SFC DWPNTS IN THE 40S...SO ALTHOUGH
H85/H7 LAPSE RATES INCR TDA...CONFIDENCE NOT HIGH ENOUGH TO ADD
ISOLD MENTION.  WL PROBABLY DVLP CU...BUT NOTHING NOTED UPSTREAM
ON STLT/RADAR TO WARRANT CONCERN.  NRN NE PCPN SHOULD PUSH TO OUR S
WITH MID LVL BACLIN ZN OR DSIPT ALTOGETHER.

NEXT CONCERN TURNS TWRD SAT/SAT NGT WHEN WRM ADVCTN RTRNS.  CURRENT
ZNS HANDLE THIS FINE WITH INCRG CLDS SAT.  HWVR ETA MORE BULLISH
THAN AVN WITH H85 THETA-E ADVCTN AND ELEVATED INSTABILITY BY SAT
NGT.  ALTHOUGH POPS LOW AND QPF NIL...TOUGH TO IGNORE NOCTURNAL
ISENT LIFT THIS TIME OF YEAR SO WL INTRODUCE LOW POPS LATE.  PCPN
CHCS ON MON ALSO LOOK GOOD.  LG WV TROF AND ASSOCD SHRT WVS NOW
CROSSING 150W EVENTUALLY DAMPEN RDG BY THAT TIME.  SYS READY TO
CROSS 130W NR 25N MAY BE A BIT STGR THAN AVN DEPICTS AND WILL ALSO
GET ABSORBED INTO WRLYS ARND THAT TIME. HVWR AVN INSTABILITY INCRS
SUN NGT WITH LOW LVL JET AND WRMFNT TRAVERSING FA SO WL ADD CHCS SUN
NGT ALG WITH MON.  NO CHGS TO EXTENDED BYD SUN NGT.
H
TEMP GUID SIMILAR THRU PD.  ETA WRMR THAN AVN/NGM THRU SAT BUT TEMPS
LOOK SIMILAR TO BOTH SETS OF MOS SO CANNOT SEE MUCH REASON TO
DEVIATE MUCH.

.DSM...NONE

SMALL

In the hours before

Local storm report, May 11, 12:32 AM CST, 5 hours 28 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
132 AM CDT FRI MAY 11 2001

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1000 PM    LOVILIA                   IA   FLOOD
05/10/01   MONROE                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.
                                          NUMEROUS CREEKS OVER
                                          ROADS.  TIME APPROXIMATE.

SMALL
Special weather statement, May 11, 4:43 AM CST, 1 hour 17 minutes before
CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
543 AM CDT FRI MAY 11 2001

THUNDERSTORMS ARE NOT EXPECTED ACROSS THE DES MOINES NATIONAL
WEATHER SERVICE FORECAST AREA TODAY OR TONIGHT.

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-121100-
ADAIR-ADAMS-APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-
CALHOUN-CARROLL-CASS-CERRO GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-
DECATUR-EMMET-FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-
HUMBOLDT-JASPER-KOSSUTH-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-
PALO ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-
UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT-
INCLUDING THE CITIES OF...ALGONA...AMES...ATLANTIC...BOONE...
CARROLL...CENTERVILLE...CHARITON...CRESTON...DENISON...
DES MOINES...ESTHERVILLE...FORT DODGE...GRINNELL...INDIANOLA...
IOWA FALLS...KNOXVILLE...LAMONI...MARSHALLTOWN...MASON CITY...
NEWTON...OSKALOOSA...OTTUMWA...PELLA...PERRY...WATERLOO...WAVERLY
AND WEBSTER CITY
543 AM CDT FRI MAY 11 2001

* EVENT TIMING... NO THUNDERSTORMS EXPECTED.

* THREAT CATEGORIES...
     TORNADO.......... NONE
     DAMAGING WINDS... NONE
     LARGE HAIL....... NONE
     FLASH FLOODING... NONE

* SPOTTER ACTIVATION OUTLOOK... NOT EXPECTED

SMALL

-------------------------------------------------------------------

THREAT KEY:
    TORNADO.......... ANY TORNADO OCCURRENCE
    DAMAGING WINDS... WINDS >= 58 MPH
    LARGE HAIL....... HAIL >= 3/4 INCH DIAMETER
    FLASH FLOODING... FLOODING CAUSED BY HEAVY RAINS WITHIN 6 HOURS
                      OF RAIN EVENT. POSES THREAT TO LIFE OR
                      PROPERTY.

THREAT CATEGORY KEY:  PROBABILITY OF THREAT OCCURRING WITHIN 25
                      MILES OF POINT WITHIN FORECAST AREA
    NONE....... NOT EXPECTED.  LESS THAN 5% ( 2% FOR TORNADOES)
    LOW........ 5-15% (2-15% FOR TORNADOES)
    MODERATE... 25-35%
    HIGH....... 45% OR GREATER

SPOTTER ACTIVATION OUTLOOK KEY:
    NOT EXPECTED
    LOW........ ACTIVATION POSSIBLE BUT NOT LIKELY
    MODERATE... POSSIBILITIES ABOUT 50-50
    HIGH....... ACTIVATION LIKELY

FOR MORE INFORMATION ON PROBABILISTIC SEVERE WEATHER OUTLOOKS...GO
TO THE STORM PREDICTION CENTER WEBSITE AT
WWW.SPC.NOAA.GOV/PRODUCTS/OUTLOOK/PROBINFO.HTML .

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

8 flood. Local standard time, as filed.

Flood, Clarke

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Clarke forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.029, -93.785 (the zone’s center; the record gives no point)

Flood, Decatur

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Decatur forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
40.738, -93.786 (the zone’s center; the record gives no point)

Flood, Lucas

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Lucas forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.029, -93.328 (the zone’s center; the record gives no point)

Flood, Mahaska

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Mahaska forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.335, -92.641 (the zone’s center; the record gives no point)

Flood, Marion

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Marion forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.334, -93.099 (the zone’s center; the record gives no point)

Flood, Monroe

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Monroe forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.030, -92.869 (the zone’s center; the record gives no point)

Flood, Wapello

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Wapello forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
41.031, -92.409 (the zone’s center; the record gives no point)

Flood, Wayne

When
May 11, 6:00 AM CST to May 14, 2:00 PM CST
Where
Wayne forecast zone
Property damage
$25,000
Reported by
OFFICIAL NWS OBS.
Coordinates
40.740, -93.327 (the zone’s center; the record gives no point)

What these are

Flood
Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Iowa in 2001Every state in 2001This day in weather historyWarnings in Iowa, May 2001

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5242547, 5242548, 5242549, 5242550, 5242551, 5242552, 5242553, 5242554.