Tornado and Hail in Iowa, April 20 to 21, 2001

Name: Tornado and Hail in Iowa, April 20 to 21, 2001
Start: 2001-04-20T20:56
End: 2001-04-21T00:10
Location: Iowa

April 20 to 21, 2001 · NWS DMX · 57 events in 23 counties and zones

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: $1.3 million
Crop damage: None recorded
Events: 57

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.

A complex and active weather pattern was in place over the upper Midwest. A warm front lifted north across the state during the previous day, allowing a strong surge of moisture to flow north from the Gulf of Mexico. Temperatures rose into the 70s to low 80s as surface dew point temperatures rose into the upper 50s and 60s across the state. By the early evening hours, a frontal boundary extended from near Sioux City east-northeast into the northeast corner of the state. Thunderstorms fired along this front and became severe during the evening. These storms produced very heavy rain with numerous reports of hail. For the most part, the hail was around an inch in diameter with the storms. There were a few reports of hail up to the size of golf balls however. Reports of golf ball size hail were received from the Ringsted area of Emmet County, and also from the Fraser area of Boone County. Two things were taking place during the evening. While the thunderstorms were firing along the warm front over northern Iowa, a strong low pressure system was racing out of Colorado. CAPE values across northeast Kansas into Iowa were in the 2000 to 3000 J/Kg range as a dry line extending south from the low approached the area. Strong thunderstorms developed over northeast Colorado and raced east across Nebraska and Kansas. The thunderstorms took on a bow echo configuration as they headed across the Plains at more than 60 MPH. High winds raked Nebraska and Kansas before moving into Iowa. There were numerous reports of winds of 60 to 80 MPH as the line advanced across the west half of Iowa with numerous reports of trees and power lines downed. As the storms moved through Carroll County, several outbuildings were destroyed in the Templeton area. Machine sheds were totally destroyed in Adair County by the high winds. Further northwest, in Greene County, a barn was flattened north of Scranton. Damage continued as the storms continued east with reports of outbuildings damaged or destroyed toward Hamilton County. One of the most damaging events of the night took place late in the storm cycle. The storms turned into wind producers. High winds hit the Lake Mills area in Winnebago County for example. A barn and several sheds were destroyed by the winds around 80 MPH. As the storms moved into Hardin County, a microburst occurred west of the Iowa Falls area with winds estimated around 85 MPH. A tornado touched down briefly in the community of Alden, causing considerable damage in the town. The tornado touched down in two locations of the town, damaging several buildings four blocks apart. Concrete blocks were picked up and thrown 50 to 75 yards and roofs of the affected buildings were strewn one quarter to three eighths of a mile downstream. One business was damages with estimated damage around $180,000. On a farm at the edge of town damage was estimated at $100,000. Numerous trees were downed on Highways 491 and D15, blocking travel in the area. Shortly after this event occurred, the storms weakened and continued moving northeast.

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 Apr 20, 1:55 PM CST, 7 hours 1 minute earlier.

Area forecast discussion, Apr 20, 1:55 PM CST, 7 hours 1 minute before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
255 PM CDT FRI APR 20 2001

RATHER DIFFICULT FCST AHD WITH BNDRY MOVG BACK AND FORTH AND MDL
DIFFERENCES COMPOUNDING PROBLEM.  MAIN CONCERNS WL BE TSTM TRENDS
TNGT...AND AGN SAT NGT INTO MON.  WATER VAPOR IMAGERY SHOWS PAC MSTR
FETCH INTO CNTRL PLAINS...AND EXTRAPOLATION OF BACK EDGE OF UVM
ENHANCEMENT ENTERS WRN IA ARND 03Z.  SPEED MAX ALSO NOTED ROUNDING
BOTTOM OF UPR LVL TROF ACRS SRN CA AND RIGHT ENTRANCE RGN OF THIS
FEATURE MAY AID DVLPMT TMRW NGT.  AC HAS RECENTLY DVLPD OVR KS
PER VISBLE STLT IMAGERY AND THIS RELFECTION OF ELEVATED INSTABILITY
SHOULD MOVE INTO IA ARND SAME TIME AS AFOREMENTIONED SYNOPTIC SCALE
UVM.  DO NOT SEEM MUCH IN THE WAY OF SFC BASED DVLPMT THIS EVEN.
STLT DERIVED AND LAPS DATA INDC AMS STILL QUITE CAPPED WITH CIN AOA
100 J/KG.  RECENT SFC ANLYS SHOW PRES FALLS HAVE BEEN EXPANDING ACRS
NE WITH STEADILY BACKING SFC WNDS.  WRMFNT MOVG NWD AND NOW ALG
NE/KS BORDER WITH CDFNT TRAILING MN LOW INTO N CNTRL IA.  18Z MSAS
ANLYS AND EYEBALL OF PROFILER DATA INDC DEEP CNVGNC INVOF WRMFNT BUT
LAPS SOUNDINGS HAVE MSTR LACKING.  KS/OK H85 WNDS HAVE BEEN BACKING
HWVR SO XPC DEEPER MSTR TO INCR THIS EVEN WHICH SHOULD COMBINE WITH
FORCING TO PRODUCE MCS AND ELEVATED CONVECTION OVR IA...BUT QUICK
NEWD MOVMT SHOULD PRECLUDE SGFNT FLASH FLOODING.  FLASH FLOOD GUID
INDCS WE CAN TAKE INITIAL EVENT SO WL NOT ISSUE ANY HEADLN ATTM.
SVR WX POSSIBLE HWVR WITH STG 0-3KM SHEAR AND STEEP LAPSE RATES
SUPPORTING WND DAMAGE AND HAIL RESPECTIVELY.

SYS SHOULD PUSH THRU TMRW WITH TEMPORARY BREAK.  HWVR SITUATION
RELOADS AGN WITH WRMFNT SETTING UP ACRS KS AND NRN MO.  MDLS DEPICT
ANOTHER ROUND OF THETA-E ADVCTN OVR BNDRY SAT NGT MAINLY WRN
2/3RDS.  INSTABILITY AND MSTR LVLS NOT QUITE AS HIGH...BUT COULD
STILL BE RATHER LRG AREA OF PCPN.  BY SUN MDLS BEGIN TO HAVE SGFNT
DIFFERENCES.  NGM SEEMS TOO FAST...WITH AVN SLOWER AND ETA FASTER.
COMPROMISE MAY BE BEST BET HERE.  SYSS OFTEN EJECT SLOWER THAN
XPCD...SPCLLY WHEN THEY ARE STILL OFFSHORE AT MDL RUN...BUT SPEED
MAX NOTED IN WV IMAGERY MAY LIFT TROF OUT FASTER.  THIS WOULD PLACE
TRIPLE POINT SOMEWHERE OVR N CNTRL KS AT 00Z MON WITH WRMFNT NEWD TO
NR KFOD.  WL GRADIATE POPS FM HIGHEST NW TO LOWEST SE ON SUN...AND
BROADBRUSH OF TSTM CHCS SUN NGT WITH CDFNT CONTG TO SLIDE ACRS FA.
WL ISSUED FLOOD POTENTIAL OUTLOOK TO HIGHLIGHT CHCS OF RAIN THRU
MUCH OF WEEKEND.

TEMP GUID ALL OVER THE PLACE...SPCLLY SUN.  NGM MOS MUCH COOLER DUE
TO FASTER MOVMT...BUT ETA MDL TEMPS COOL AS WELL.  THUS WL GO A
CATEGORY OR TWO BLO WRMR AVN MOS.

COORD W/ARX AND DVN.

EXTENDED PD...
EURO MDLS...SPCLLY UK CONT TO BE FASTER WITH MON SYS AS IS CANADIAN
MDL.  NOGAPS SLOWER SIMILAR TO MRF.  MRF ENSEMBLES IN GOOD AGREEMENT
WITH OPERATIONAL RUN BY MIDWEEK BUT SYS ALG 140W CONSIDERABLY SLOWER
IN ENSEMBLE RUNS.  THIS MAY KEEP US IN PROLONGED RIDGING INTO NEXT
WEEKEND.  FOR ACTIVE WX EARLY IN PD CANNOT SEE MUCH REASON TO
DEVIATE FM MRF WHICH HAS HAD GOOD RUN TO RUN CONTINUITY.  THIS WOULD
KEEP TSTMS IN FCST ON MON WITH ENHANCED LOW LVL CNVGNC...SPCLLY SERN
HLF...WHEN SHRT WV NOW OFF NRN CA CST FINALLY BRINGS LG WV TROF AND
MAIN ASSOCD SFC REFLECTION THRU.  WL ALSO ADD CHC LINGERING SHWRS
BHND SYS EARLY TUE.  OTHERWISE FAIR AND SEASONAL WX FOR MUCH OF NEXT
WEEK.  CANNOT SEE REASON 0NOT TO FOLLOW MRF MOS TEMPS.

.DSM...NONE

SMALL

In the hours before

Special weather statement, Apr 20, 3:00 PM CST, 5 hours 56 minutes before

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
400 PM CDT FRI APR 20 2001

A WARM FRONT WILL MOVE NORTH ACROSS IOWA OVERNIGHT.  MOIST AIR
MOVING NORTH WITH THE FRONT IS EXPECTED TO DESTABILIZE THE
ATMOSPHERE THIS EVENING.  SHOWERS AND THUNDERSTORMS SHOULD DEVELOP
ALONG THE FRONT DURING THE EVENING AND SPREAD NORTHEAST OVERNIGHT.
PRIMARY THREATS WILL BE LARGE HAIL AND DAMAGING STRAIGHT LINE WINDS.

SEE SITE SPECIFIC DETAILS BELOW FOR MORE INFORMATION.

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-211100-
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
335 PM CDT FRI APR 20 2001

* EVENT TIMING... FROM 7 PM THROUGH 6 AM

* THREAT CATEGORIES...
     TORNADO.......... LOW
     DAMAGING WINDS... MODERATE
     LARGE HAIL....... MODERATE
     FLASH FLOODING... LOW

* SPOTTER ACTIVATION OUTLOOK... MODERATE

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

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 .

COGIL

The radar

The Omaha radar (KOAX), 107 km away, was scanning. The volume nearest the first event began at 02:57 UTC.

Open the radar archive at this moment

Event by event

40 thunderstorm wind, 16 hail, 1 tornado. Local standard time, as filed.

Thunderstorm Wind, Cass

When: April 20, 8:56 PM CST
Where: Cass County, Lewis
Measured: 50 kt (58 mph)
Property damage: $1,000
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 41.300, -95.083

Hail, Pocahontas

When: April 20, 9:10 PM CST to 9:15 PM CST
Where: Pocahontas County, 1 mi E of Pocahontas
Measured: 0.88 in hail
Property damage: $3,000
Reported by: TRAINED SPOTTER
Coordinates: 42.733, -94.650

Hail, Pocahontas

When: April 20, 9:14 PM CST
Where: Pocahontas County, Rolfe
Measured: 1 in hail
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.817, -94.517

Hail, Humboldt

When: April 20, 9:32 PM CST
Where: Humboldt County, 1 mi W of Humboldt
Measured: 0.88 in hail
Property damage: $3,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.717, -94.233

Hail, Humboldt

When: April 20, 9:35 PM CST
Where: Humboldt County, 12 mi W of Humboldt
Measured: 0.88 in hail
Property damage: $2,000
Reported by: TRAINED SPOTTER
Coordinates: 42.717, -94.450

Hail, Pocahontas

When: April 20, 9:43 PM CST
Where: Pocahontas County, Plover
Measured: 1.25 in hail
Property damage: $7,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.883, -94.633

Hail, Pocahontas

When: April 20, 9:50 PM CST to 10:00 PM CST
Where: Pocahontas County, 13 mi NE of Pocahontas
Measured: 1 in hail
Property damage: $10,000
Reported by: UNKNOWN
Coordinates: 42.867, -94.483

Thunderstorm Wind, Crawford

When: April 20, 9:55 PM CST
Where: Crawford County, 2 mi NW of Denison
Measured: 57 kt (66 mph)
Property damage: $100,000
Reported by: NEWSPAPER
Coordinates: 42.033, -95.383

Thunderstorm Wind, Calhoun

When: April 20, 9:58 PM CST
Where: Calhoun County, Lake City
Measured: 50 kt (58 mph)
Property damage: $5,000
Reported by: NEWSPAPER
Coordinates: 42.267, -94.733

Thunderstorm Wind, Cass

When: April 20, 9:59 PM CST
Where: Cass County, Atlantic
Measured: 52 kt (60 mph)
Property damage: $2,000
Reported by: LAW ENFORCEMENT
Coordinates: 41.400, -95.017

Thunderstorm Wind, Carroll

When: April 20, 10:00 PM CST
Where: Carroll County, Manning
Measured: 65 kt (75 mph)
Property damage: $25,000
Reported by: NEWSPAPER
Coordinates: 41.900, -95.067

Thunderstorm Wind, Cass

When: April 20, 10:01 PM CST
Where: Cass County, 1 mi NE of Atlantic
Measured: 71 kt (82 mph)
Property damage: $5,000
Reported by: BROADCAST MEDIA
Coordinates: 41.417, -95.000

Hail, Palo Alto

When: April 20, 10:01 PM CST to 10:06 PM CST
Where: Palo Alto County, 3 mi W of Emmetsburg
Measured: 1 in hail
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.117, -94.767

Thunderstorm Wind, Cass

When: April 20, 10:01 PM CST
Where: Cass County, Griswold
Measured: 52 kt (60 mph)
Property damage: $2,000
Reported by: LAW ENFORCEMENT
Coordinates: 41.233, -95.150

Thunderstorm Wind, Audubon

When: April 20, 10:04 PM CST
Where: Audubon County, Audubon
Measured: 52 kt (60 mph)
Property damage: $2,000
Reported by: AMATEUR RADIO
Coordinates: 41.717, -94.933

Hail, Palo Alto

When: April 20, 10:04 PM CST
Where: Palo Alto County, 1 mi S of Emmetsburg
Measured: 1 in hail
Property damage: $5,000
Reported by: BROADCAST MEDIA
Coordinates: 43.100, -94.700

Thunderstorm Wind, Audubon

When: April 20, 10:05 PM CST
Where: Audubon County, Audubon Arpt
Measured: 51 kt (59 mph)
Property damage: $1,000
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 41.700, -94.917

Thunderstorm Wind, Carroll

When: April 20, 10:10 PM CST
Where: Carroll County, Templeton
Measured: 68 kt (78 mph)
Property damage: $30,000
Reported by: TRAINED SPOTTER
Coordinates: 41.917, -94.950

Hail, Emmet

When: April 20, 10:12 PM CST
Where: Emmet County, Wallingford
Measured: 1 in hail
Property damage: $3,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.333, -94.833

Thunderstorm Wind, Cass

When: April 20, 10:15 PM CST
Where: Cass County, Atlantic Arpt
Measured: 54 kt (62 mph)
Property damage: $2,000
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 41.400, -95.050

Thunderstorm Wind, Adair

When: April 20, 10:15 PM CST
Where: Adair County, 6 mi N of Fontanelle
Measured: 61 kt (70 mph)
Property damage: $25,000
Reported by: LAW ENFORCEMENT
Coordinates: 41.383, -94.567

Thunderstorm Wind, Crawford

When: April 20, 10:15 PM CST
Where: Crawford County, Vail
Measured: 65 kt (75 mph)
Property damage: $30,000
Reported by: NEWSPAPER
Coordinates: 42.067, -95.200

Thunderstorm Wind, Carroll

When: April 20, 10:19 PM CST
Where: Carroll County, Carroll
Measured: 70 kt (81 mph)
Property damage: $35,000
Reported by: BROADCAST MEDIA
Coordinates: 42.067, -94.883

Thunderstorm Wind, Greene

When: April 20, 10:23 PM CST
Where: Greene County, Jefferson
Measured: 50 kt (58 mph)
Property damage: $1,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.017, -94.383

Thunderstorm Wind, Adair

When: April 20, 10:24 PM CST
Where: Adair County, Adair
Measured: 59 kt (68 mph)
Property damage: $3,000
Reported by: BROADCAST MEDIA
Coordinates: 41.500, -94.650

Thunderstorm Wind, Carroll

When: April 20, 10:25 PM CST
Where: Carroll County, Carroll Neu Arpt
Measured: 56 kt (64 mph)
Property damage: $5,000
Reported by: AMATEUR RADIO
Coordinates: 42.050, -94.783

Thunderstorm Wind, Carroll

When: April 20, 10:26 PM CST
Where: Carroll County, Breda
Measured: 57 kt (66 mph)
Property damage: $5,000
Reported by: BROADCAST MEDIA
Coordinates: 42.183, -94.983

Thunderstorm Wind, Greene

When: April 20, 10:30 PM CST
Where: Greene County, Jefferson
Measured: 56 kt (64 mph)
Property damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.017, -94.383

Hail, Kossuth

When: April 20, 10:36 PM CST
Where: Kossuth County, Burt
Measured: 0.88 in hail
Property damage: $2,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.200, -94.217

Hail, Emmet

When: April 20, 10:39 PM CST
Where: Emmet County, 2 mi W of Ringsted
Measured: 1.75 in hail
Property damage: $10,000
Reported by: BROADCAST MEDIA
Coordinates: 43.300, -94.550

Thunderstorm Wind, Greene

When: April 20, 10:40 PM CST
Where: Greene County, 3 mi N of Scranton
Measured: 70 kt (81 mph)
Property damage: $50,000
Reported by: BROADCAST MEDIA
Coordinates: 42.083, -94.550

Thunderstorm Wind, Guthrie

When: April 20, 10:44 PM CST
Where: Guthrie County, Adair
Measured: 57 kt (66 mph)
Property damage: $5,000
Reported by: BROADCAST MEDIA
Coordinates: 41.500, -94.650

Thunderstorm Wind, Dallas

When: April 20, 10:53 PM CST
Where: Dallas County, Adel
Measured: 52 kt (60 mph)
Property damage: $2,000
Reported by: EMERGENCY MANAGER
Coordinates: 41.617, -94.017

Hail, Hancock

When: April 20, 10:55 PM CST
Where: Hancock County, Crystal Lake
Measured: 1 in hail
Property damage: $3,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.217, -93.800

Thunderstorm Wind, Webster

When: April 20, 10:55 PM CST
Where: Webster County, Gowrie
Measured: 61 kt (70 mph)
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.283, -94.300

Thunderstorm Wind, Hamilton

When: April 20, 11:01 PM CST
Where: Hamilton County, Stratford
Measured: 70 kt (81 mph)
Property damage: $40,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.267, -93.933

Hail, Boone

When: April 20, 11:05 PM CST
Where: Boone County, Fraser
Measured: 1.75 in hail
Property damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.133, -93.967

Thunderstorm Wind, Boone

When: April 20, 11:05 PM CST
Where: Boone County, Fraser
Measured: 50 kt (58 mph)
Property damage: $2,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.133, -93.967

Thunderstorm Wind, Boone

When: April 20, 11:12 PM CST
Where: Boone County, 3 mi E of Boone
Measured: 53 kt (61 mph)
Property damage: $3,000
Reported by: BROADCAST MEDIA
Coordinates: 42.067, -93.817

Hail, Hamilton

When: April 20, 11:14 PM CST
Where: Hamilton County, Jewell
Measured: 0.88 in hail
Property damage: $3,000
Reported by: AMATEUR RADIO
Coordinates: 42.300, -93.650

Thunderstorm Wind, Boone

When: April 20, 11:15 PM CST
Where: Boone County, Boone
Measured: 53 kt (61 mph)
Property damage: $10,000
Reported by: BROADCAST MEDIA
Coordinates: 42.067, -93.883

Hail, Winnebago

When: April 20, 11:15 PM CST
Where: Winnebago County, 4 mi W of Forest City
Measured: 1 in hail
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.267, -93.733

Hail, Winnebago

When: April 20, 11:15 PM CST
Where: Winnebago County, 2 mi W of Forest City
Measured: 1 in hail
Property damage: $5,000
Reported by: BROADCAST MEDIA
Coordinates: 43.267, -93.683

Thunderstorm Wind, Story

When: April 20, 11:16 PM CST
Where: Story County, Ames Arpt
Measured: 51 kt (59 mph)
Property damage: $1,000
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 42.000, -93.617

Thunderstorm Wind, Story

When: April 20, 11:16 PM CST
Where: Story County, Ames
Measured: 61 kt (70 mph)
Property damage: $15,000
Reported by: TRAINED SPOTTER
Coordinates: 42.033, -93.617

Thunderstorm Wind, Boone

When: April 20, 11:17 PM CST
Where: Boone County, Sheldahl
Measured: 52 kt (60 mph)
Property damage: $3,000
Reported by: AMATEUR RADIO
Coordinates: 41.867, -93.717

Thunderstorm Wind, Story

When: April 20, 11:18 PM CST
Where: Story County, 1 mi N of Story City
Measured: 61 kt (70 mph)
Property damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.200, -93.600

Thunderstorm Wind, Story

When: April 20, 11:18 PM CST
Where: Story County, 1 mi W of Ames
Measured: 52 kt (60 mph)
Property damage: $5,000
Reported by: AMATEUR RADIO
Coordinates: 42.033, -93.633

Thunderstorm Wind, Hancock

When: April 20, 11:18 PM CST
Where: Hancock County, 5 mi NE of Corwith
Measured: 70 kt (81 mph)
Property damage: $40,000
Reported by: TRAINED SPOTTER
Coordinates: 43.033, -93.900

Thunderstorm Wind, Story

When: April 20, 11:22 PM CST
Where: Story County, 1 mi W of Ames
Measured: 52 kt (60 mph)
Property damage: $3,000
Reported by: AMATEUR RADIO
Coordinates: 42.033, -93.633

Thunderstorm Wind, Hancock

When: April 20, 11:22 PM CST
Where: Hancock County, 2 mi SE of Corwith
Measured: 56 kt (64 mph)
Property damage: $20,000
Reported by: NEWSPAPER
Coordinates: 42.967, -93.933

Thunderstorm Wind, Hamilton

When: April 20, 11:30 PM CST
Where: Hamilton County, 4 mi S of Stanhope
Measured: 65 kt (75 mph)
Property damage: $30,000
Reported by: BROADCAST MEDIA
Coordinates: 42.233, -93.800

Thunderstorm Wind, Winnebago

When: April 20, 11:30 PM CST
Where: Winnebago County, Lake Mills
Measured: 70 kt (81 mph)
Property damage: $100,000
Reported by: NEWSPAPER
Coordinates: 43.417, -93.533

Thunderstorm Wind, Franklin

When: April 20, 11:43 PM CST
Where: Franklin County, Latimer
Measured: 52 kt (60 mph)
Property damage: $3,000
Reported by: AMATEUR RADIO
Coordinates: 42.767, -93.367

Thunderstorm Wind, Hardin

When: April 20, 11:43 PM CST
Where: Hardin County, 3 mi W of Iowa Falls
Measured: 75 kt (86 mph)
Property damage: $100,000
Reported by: EMERGENCY MANAGER
Coordinates: 42.517, -93.333

Microburst wind event.

Tornado, Hardin

When: April 20, 11:46 PM CST to 11:47 PM CST
Where: Hardin County, Alden
Rating: F1
Path length: 0.6 mi
Path width: 50 yd
Property damage: $500,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.517, -93.533

Short touchdown within the town of Alden.

Thunderstorm Wind, Grundy

When: April 21, 12:10 AM CST
Where: Grundy County, 2 mi NW of Wellsburg
Measured: 52 kt (60 mph)
Property damage: $3,000
Reported by: TRAINED SPOTTER
Coordinates: 42.450, -92.950

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.
Tornado: A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.

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

The same day elsewhere

Every storm in Iowa in 2001 Every state in 2001 This day in weather history The tornado archive for Iowa, 2001 Warnings in Iowa, April 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: 5237582, 5237307, 5237308, 5237425, 5237426, 5237427, 5237428, 5237584, 5237587, 5237429, 5237586, 5237430, 5237431, 5237432, 5237433, 5237434, 5237435, 5237436, 5237437, 5237438, 5237439, 5237588, 5237440, 5237441, 5237442, 5237443, 5237444, 5237445, 5237446, 5237447, 5237448, 5237449, 5237450, 5237451, 5237452, 5237453, 5237454, 5237455, 5237456, 5237457, and more.