Iowa, 2001

Hail and Damaging Winds in Iowa, August 2, 2001

August 2, 2001 · NWS DMX · 5 events in 4 counties and zones

The airmass over Iowa was very unstable during the morning hours of the 2nd. Surface dew points were in the mid 70s to around 80 with temperatures in the upper 70s to low 80s.

Where it happened

Every event with a place to put it. 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
$18,000
Crop damage
$86,000
Events
5

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.

The airmass over Iowa was very unstable during the morning hours of the 2nd. Surface dew points were in the mid 70s to around 80 with temperatures in the upper 70s to low 80s. During the previous night thunderstorms fired over north central and parts of northwest Iowa. A strong outflow boundary was lain down to the south of the storms, but really didn't have a dramatic effect on thunderstorm development after sunrise. Clearly, new thunderstorm development was elevated in nature with the base of the thunderstorms around 12,000 feet above the ground. A cluster of thunderstorms moved into northwest Iowa shortly after sunrise. This cluster was actually the remains of an MCS that developed over northeast Colorado the night before. As the storms moved into northwest Iowa, golf ball size hail and winds as strong as 98 MPH blew into Sioux City. The storms turned east and moved into Sac and Calhoun Counties. As they did, winds around 60 MPH were reported in the Schaller, Early, and Jolley areas. As the storms moved across northern Pocahontas County, high winds swept south through Pocahontas and areas just south of Pocahontas. Crops were flattened by the 75 MPH winds with the storms. Hail was not a major factor with these storms as the freezing level was ver high, over 16.000 feet. The storms weakened as they moved east, but rekindled briefly as they moved across Marshall County. The storm dropped nickle size hail northeast of the Green Mountain area before weakening again.

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 Aug 2, 1:25 AM CST, 6 hours 45 minutes earlier.

Area forecast discussion, Aug 2, 1:25 AM CST, 6 hours 45 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
225 AM CDT THU AUG 2 2001

FORECASTS KEEP GETTING TOUGHER - HEAT SOUTH AND POPS MAIN CHALLENGE
AGAIN TODAY.

SFC FRONT DRAPED ACROSS STATE...FROM TKE TO CCY AND MOVING LITTLE.
TSRA HAVE DEVELOPED IN NRN CWA JUST NORTH OF FRONT AT NOSE OF
WHOPPING 20-25KT SW LLJ. PLENTY OF JUICE AVAILABLE THOUGH WITH 2.12
INCHES AT 00Z FOR PWATS AT OAX AND MID 70S DEWPOINTS ALONG/S OF
FRONT. 88D OHP SHOWING PRETTY GOOD RAINS...THOUGH NOT WIDESPREAD.
SVN SPOTTER JUST CALLED IN WITH INCH PER HOUR RATES.  CORFIDI
VECTORS WOULD PULL THIS STUFF EVER SO SLOWLY SOUTHWARD NEXT FEW
HOURS. 50H RIDGE RETROGRADES NEXT FEW DAYS...EVENTUALLY PUTTING CWA
IN NW FLOW. VORT MAX IN MONSOONAL FLO OVR NM/CO BORDER WILL PROVIDE
FOCUS JUST TO OUR WEST TONIGHT.

ETA CONTINUES TO PUSH FRONT AND PRECIP TOO FAR SOUTH. ITS NOT
BAD...JUST TOO FAR SOUTH.  ADJUSTED NORTH A HUNDRED MILES OR SO AND
IT LOOKS A LOT LIKE THE AVN - AND NEW HPC QPF.  WILL FOLLOW.

TODAY...COLD POOL FROM CONVECTION TO THE NORTH WILL PUSH TO I80 WEST
OF I35 THIS AFTERNOON...BUT NOT BEFORE HEAT INDICES PUSH UP TO
DANGEROUS LEVELS AGAIN.  BLOW OFF FROM CONVECTION MAY INHIBIT ALO
HI'S BETTER TODAY THAN YESTERDAY.  WILL NO LONGER SPLIT DSM METRO
THOUGH AND HAVE INCLUDED DALLAS CO. IN NPW.  EXPECT PRECIP POTENTIAL
TO END THIS MORNING FAR NORTH. WILL HAVE TO RUN WDLY SCT...HEAVY
POTENTIAL...CENTRAL THIRD OF CWA...AND GO WITH AFTERNOON SMALL POPS
FAR SOUTH.  TEMPS...WARMEST GUID IN NPW AREA/LOWER MID 80S IN NORTH
HALF.

TONIGHT...INFLOW INTO WHATS LEFT OF BOUNDARY IS MINIMAL AT BEST
ALONG I-80 CORRIDOR THIS EVENING. ALREADY HAVE POPS IN WC CWA...AND
WILL LEAVE ALONG.  ALONG I-80 AND E OF 35...TOUGHER TO FIGURE OUT
WHATS TO DO...BUT A SMALL POP MAY BE THE WAY TO GO.  LATER IN WC
INTO SW...EXPECT A SMALL COMPLEX OF TSRA INDUCED BY AFOREMENTIONED
NM/CO VORT MAX TO PERHAPS BRUSH DNS TO CSQ LINE. LLJ AGAIN NOT GREAT
SO DON'T EXPECT TOO MUCH.  WILL HANDLE THAT WITH POPS TOO.  DRY
NORTH AND NE.  GUID TEMPS AND GOING FCST CLOSE ON TEMPS - NO REASON
TO DEVIATE.

FRI INTO FRI NIGHT...SEE LITTLE CHC FOAR RAIN AT THIS POINT.  GOING
'CAST ON TRACK.

.DSM...HEAT ADVY OVRNGT ROUGHLY ALG AND S OF A AIO TO DSM TO MIW
LINE LINE.
IAZ049-050-059>062-070>075-081>086-092>097-

In the hours before

Special weather statement, Aug 2, 4:35 AM CST, 3 hours 35 minutes before
CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
535 AM CDT THU AUG 2 2001

A WEAK COLD FRONT EXTENDING FROM NORTHEAST IOWA INTO WEST CENTRAL
SECTIONS OF THE STATE WILL PROVIDE A FOCUS FOR THUNDERSTORM
DEVELOPMENT ON AND OFF TODAY.  ABUNDANT MOISTURE REMAINS ACROSS THE
REGION WHICH WILL HELP FUEL ANY THUNDERSTORMS THAT DEVELOP.  WHILE
INSTABILITY IS MODERATELY HIGH...WIND SHEAR IS QUITE WEAK AS IS
INFLOW INTO AND OVER THE FRONT.  WARM TEMPERATURES ALOFT WILL
INHIBIT MOST THUNDERSTORMS FROM PRODUCING LARGE HAIL...HOWEVER SOME
DAMAGING WIND GUSTS MAY OCCUR. ADDITIONALLY LOCALLY HEAVY RAINFALL
MAY OCCUR DUE TO THE SLOW MOVEMENT OF THE STORMS AND DEEP MOISTURE.

SEE SITE SPECIFIC DETAILS BELOW FOR MORE INFORMATION.

IAZ004>007-015>017-031100-
CERRO GORDO-EMMET-HANCOCK-KOSSUTH-PALO ALTO-WINNEBAGO-WORTH-
INCLUDING THE CITIES OF...ALGONA...ESTHERVILLE AND MASON CITY
529 AM CDT THU AUG 2 2001

* EVENT TIMING... THROUGH NOON.

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

* SPOTTER ACTIVATION OUTLOOK... LOW.

IAZ023>028-033>039-044>050-057>062-070>074-031100-
ADAIR-AUDUBON-BLACK
HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CASS-CRAWFORD-DALLAS-
FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HARDIN-HUMBOLDT-JASPER-
MADISON-MARION-MARSHALL-POCAHONTAS-POLK-POWESHIEK-SAC-STORY-TAMA-
WARREN-WEBSTER-WRIGHT-
INCLUDING THE CITIES OF...AMES...ATLANTIC...BOONE...CARROLL...
DENISON...DES MOINES...FORT DODGE...GRINNELL...INDIANOLA...IOWA
FALLS...KNOXVILLE...MARSHALLTOWN...NEWTON...PELLA...PERRY...
WATERLOO...WAVERLY AND WEBSTER CITY
529 AM CDT THU AUG 2 2001

* EVENT TIMING... MAINLY THROUGH NOON.

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

* SPOTTER ACTIVATION OUTLOOK... LOW.

IAZ075-081>086-092>097-031100-
ADAMS-APPANOOSE-CLARKE-DAVIS-DECATUR-LUCAS-MAHASKA-MONROE-RINGGOLD-
TAYLOR-UNION-WAPELLO-WAYNE-
INCLUDING THE CITIES OF...CENTERVILLE...CHARITON...CRESTON...
LAMONI...OSKALOOSA AND OTTUMWA
529 AM CDT THU AUG 2 2001

* EVENT TIMING... THROUGH 5 PM.

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

* SPOTTER ACTIVATION OUTLOOK... LOW.

SEARCY

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

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 Des Moines radar (KDMX), 156 km away, was scanning. The volume nearest the first event began at 14:09 UTC.

Open the radar archive at this moment

Event by event

4 thunderstorm wind, 1 hail. Local standard time, as filed.

Thunderstorm Wind, Sac

When
August 2, 8:10 AM CST
Where
Sac County, Schaller
Measured
52 kt (60 mph)
Property damage
$5,000
Crop damage
$2,000
Reported by
TRAINED SPOTTER
Coordinates
42.500, -95.300

Thunderstorm Wind, Sac

When
August 2, 8:20 AM CST
Where
Sac County, Early
Measured
52 kt (60 mph)
Property damage
$5,000
Crop damage
$2,000
Reported by
TRAINED SPOTTER
Coordinates
42.467, -95.150

Thunderstorm Wind, Calhoun

When
August 2, 8:42 AM CST
Where
Calhoun County, 1 mi NW of Jolley
Measured
52 kt (60 mph)
Property damage
$2,000
Crop damage
$2,000
Reported by
LAW ENFORCEMENT
Coordinates
42.500, -94.733

Thunderstorm Wind, Pocahontas

When
August 2, 8:55 AM CST
Where
Pocahontas County, 1 mi S of Pocahontas
Measured
65 kt (75 mph)
Property damage
$5,000
Crop damage
$75,000
Reported by
NEWSPAPER
Coordinates
42.717, -94.667

Hail, Marshall

When
August 2, 11:32 AM CST
Where
Marshall County, 4 mi NE of Green Mtn
Measured
0.88 in hail
Property damage
$1,000
Crop damage
$5,000
Reported by
TRAINED SPOTTER
Coordinates
42.133, -92.767

What these are

Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

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, August 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: 5260348, 5260349, 5260652, 5260654, 5260653.