Iowa, 2001

Hail in Iowa, July 17, 2001

July 17, 2001 · NWS DMX · 2 events in 2 counties and zones

Thunderstorms erupted over central and east central Iowa ahead of an approaching warm front from the south. Very moist air was drawn north into Iowa, with dew point temperatures soaring into the upper 70s to mid 80s over southwest into central Iowa by late afternoon.

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

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The toll

Deaths
0
Injuries
0
Property damage
$8,000
Crop damage
$20,000
Events
2

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.

Thunderstorms erupted over central and east central Iowa ahead of an approaching warm front from the south. Very moist air was drawn north into Iowa, with dew point temperatures soaring into the upper 70s to mid 80s over southwest into central Iowa by late afternoon. The thunderstorms became severe over Tama County and dropped golf ball size hail south of the town of Montour. The storms continued to move southeast into Poweshiek County and dropped ping ball size hail north of Brooklyn.

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 Jul 17, 1:57 AM CST, 10 hours 30 minutes earlier.

Area forecast discussion, Jul 17, 1:57 AM CST, 10 hours 30 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
257 AM CDT TUE JUL 17 2001

HEAT AND PCPN CHANCES ARE PRIMARY PROBLEMS FOR THIS FORECAST.
CURRENTLY...CONVECTION MOVING ACRS W CWA CONTINUES TO DIMINISH
RAPIDLY.  THIS ALSO SEEN BY WARMING OF CLOUD TOP ON IR SAT PICS.
OTHERWISE...PLENTY OF WAA AND MOISTURE ADVECTION WITH DEWPOINTS NOW
INTO THE MID 70S IN SW IA.

MODELS CONTINUE TO HAVE DIFFERENCES IN CONVECTIVE DEVELOPMENT AND
SUBSEQUENT QPF PLACEMENT.  CAP EVENTUALLY OVERTAKES MUCH OF THE CWA
WITH DEVELOPMENT OF CONVECTION BEING LIMITED.  HOWEVER...TSRA COULD
STILL ADVECT INTO THE CWA FROM THE N DURING THE NIGHTTIME HOURS
ALONG THE INSTABILITY AXIS...THEREFORE POPS IN ZONES WL PRIMARILY BE
DURING THE NIGHT.

HEAT TO INCREASE TODAY AS 850 MB TEMPS RISE INTO THE MID 20S ACRS
THE WEST.  DEWPOINTS ALSO CLIMB WITH MOST MODEL OUTPUT SUGGESTING
UPPER 70S TO AROUND 80 BY THIS AFTERNOON...ESPECIALLY SW HALF OF
CWA.  WITH DEWPOINTS THIS HIGH...ONLY TAKES LOWER 90S TO PUSH THE
HEAT INDEX INTO ADVISORY CATEGORY...SO WL ISSUE ADVISORY FOR SW HALF
TODAY.  THIS WL PROBABLY NEED TO BE EXTENDED/EXPANDED INTO WEDNESDAY
AS IT APPEARS THE HEAT AND MUGGIES SHOULD CONTINUE.  LTL CHANGE TO
EXTENDED AT THIS TIME.

.DSM...HEAT ADVISORY TODAY IAZ023-033>035-044>047-057>060-070>074-
081>086-092>097.

COGIL

The radar

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

Open the radar archive at this moment

Event by event

2 hail. Local standard time, as filed.

Hail, Tama

When
July 17, 12:27 PM CST
Where
Tama County, 4 mi S of Montour
Measured
1.75 in hail
Property damage
$5,000
Crop damage
$10,000
Reported by
LAW ENFORCEMENT
Coordinates
41.917, -92.717

Hail, Poweshiek

When
July 17, 12:56 PM CST
Where
Poweshiek County, 4 mi N of Brooklyn
Measured
1.25 in hail
Property damage
$3,000
Crop damage
$10,000
Reported by
TRAINED SPOTTER
Coordinates
41.783, -92.450

What these are

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, July 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: 5252280, 5252281.