A strong upper level ridge of high pressure developed over the Rockies during the previous several days.  The weather pattern became a pattern more typical of July and early August rather than May as convection became established in the classic "ring of fire" configuration.  Thunderstorms erupted during the night of the 12th and early morning of the 13th.  The convection was all elevated in nature.  The severe weather took the form of hail with this event.  A deep layer of cool air at the surface was in place, limiting the threat of the storms becoming tornadic or producing high winds.  Thunderstorms moved southeast across the state for about 12 hours.  Many of the storms produced large hail.  During the late morning into the early afternoon of the 13th, thunderstorms back developed over central Iowa, then trained southeast into south central Iowa.  Heavy rainfall occurred just to the south of the Des Moines area in Warren County.  Two and one half inches of rain fell in under two hours time in the town of Norwalk.  Rainfall from the event was in excess of four inches in places, especially the southwest half of the county.  Roads were reported under water, including some state highways.  Hail was widespread with this event.  with numerous places from northwest into south central Iowa reporting hail anywhere from three quarters of an inch in diameter, up to golf ball size.  There were numerous reports of damage to vehicles as well as the roofs of houses.  The largest hail occurred in the Atlantic area of Cass County.  One of the stronger storms on the southwest edge of the convection dropped hail up to three inches in diameter on the city.  The hail caused considerable damage around town to both roof tops as well as many cars.

Hail in WEBSTER, IOWA
From 13-MAY-01 06:15:00 to 13-MAY-01 06:15:00 (CST)
Location: GOWRIE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Hail in CASS, IOWA
From 13-MAY-01 06:20:00 to 13-MAY-01 06:20:00 (CST)
Location: LEWIS
Magnitude: 0.88 
Property damage: 2K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 13-MAY-01 08:20:00 to 13-MAY-01 08:20:00 (CST)
Location: NORWAY CENTER
Magnitude: 1.75 
Property damage: 25K
Crop damage: 3K
Reported by: EMERGENCY MANAGER

Hail in MARION, IOWA
From 13-MAY-01 13:15:00 to 13-MAY-01 13:15:00 (CST)
Location: PLEASANTVILLE
Magnitude: 0.75 
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in TAYLOR, IOWA
From 13-MAY-01 08:27:00 to 13-MAY-01 08:27:00 (CST)
Location: NEW MARKET
Magnitude: 1.75 
Property damage: 25K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in CALHOUN, IOWA
From 13-MAY-01 05:35:00 to 13-MAY-01 05:35:00 (CST)
Location: JOLLEY
Magnitude: 0.75 
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 13-MAY-01 07:50:00 to 13-MAY-01 07:50:00 (CST)
Location: ATLANTIC
Magnitude: 0.88 
Property damage: 2K
Crop damage: 2K
Reported by: AMATEUR RADIO

Hail in ADAMS, IOWA
From 13-MAY-01 07:20:00 to 13-MAY-01 07:20:00 (CST)
Location: CORNING
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 06:15:00 to 13-MAY-01 06:15:00 (CST)
Location: ORIENT
Magnitude: 0.88 
Property damage: 3K
Crop damage: 1K
Reported by: EMERGENCY MANAGER

Hail in CASS, IOWA
From 13-MAY-01 08:01:00 to 13-MAY-01 08:01:00 (CST)
Location: ATLANTIC
Magnitude: 1.75 
Property damage: 5K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Hail in WAPELLO, IOWA
From 13-MAY-01 17:58:00 to 13-MAY-01 17:58:00 (CST)
Location: OTTUMWA
Magnitude: 1.25 
Property damage: 10K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 13-MAY-01 07:31:00 to 13-MAY-01 07:31:00 (CST)
Location: MARNE
Magnitude: 2.00 
Property damage: 25K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Hail in WARREN, IOWA
From 13-MAY-01 10:50:00 to 13-MAY-01 10:50:00 (CST)
Location: MARTENSDALE
Magnitude: 1.75 
Property damage: 20K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 13-MAY-01 06:45:00 to 13-MAY-01 06:45:00 (CST)
Location: GRISWOLD
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in CASS, IOWA
From 13-MAY-01 06:20:00 to 13-MAY-01 06:20:00 (CST)
Location: GRISWOLD
Magnitude: 1.75 
Property damage: 15K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 13-MAY-01 07:12:00 to 13-MAY-01 07:12:00 (CST)
Location: PATON
Magnitude: 0.75 
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in POCAHONTAS, IOWA
From 13-MAY-01 05:25:00 to 13-MAY-01 05:25:00 (CST)
Location: FONDA
Magnitude: 0.88 
Property damage: 3K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in WARREN, IOWA
From 13-MAY-01 10:50:00 to 13-MAY-01 10:50:00 (CST)
Location: MARTENSDALE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in TAYLOR, IOWA
From 13-MAY-01 08:30:00 to 13-MAY-01 08:30:00 (CST)
Location: GRAVITY
Magnitude: 0.75 
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in DAVIS, IOWA
From 13-MAY-01 18:00:00 to 13-MAY-01 18:00:00 (CST)
Location: FLORIS
Magnitude: 0.88 
Property damage: 2K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in CALHOUN, IOWA
From 13-MAY-01 06:10:00 to 13-MAY-01 06:10:00 (CST)
Location: ROCKWELL CITY
Magnitude: 0.88 
Property damage: 3K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in ADAMS, IOWA
From 13-MAY-01 07:13:00 to 13-MAY-01 07:13:00 (CST)
Location: WILLIAMSON
Magnitude: 0.88 
Property damage: 2K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in CASS, IOWA
From 13-MAY-01 06:32:00 to 13-MAY-01 06:32:00 (CST)
Location: GRISWOLD
Magnitude: 0.75 
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 13-MAY-01 07:35:00 to 13-MAY-01 07:35:00 (CST)
Location: PATON
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Heavy Rain in WARREN, IOWA
From 13-MAY-01 12:13:00 to 13-MAY-01 12:13:00 (CST)
Location: NORWALK
Magnitude: 2.5 
Property damage: 2K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Two and one half inches of rain in under two hours time.

Hail in ADAIR, IOWA
From 13-MAY-01 08:50:00 to 13-MAY-01 08:50:00 (CST)
Location: BRIDGEWATER
Magnitude: 1.00 
Property damage: 5K
Crop damage: 1K
Reported by: EMERGENCY MANAGER

Hail in WARREN, IOWA
From 13-MAY-01 13:01:00 to 13-MAY-01 13:01:00 (CST)
Location: HARTFORD
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in WARREN, IOWA
From 13-MAY-01 12:24:00 to 13-MAY-01 12:24:00 (CST)
Location: INDIANOLA
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in DECATUR, IOWA
From 13-MAY-01 11:11:00 to 13-MAY-01 11:11:00 (CST)
Location: GRAND RIVER
Magnitude: 1.75 
Property damage: 20K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 09:19:00 to 13-MAY-01 09:19:00 (CST)
Location: ORIENT
Magnitude: 1.75 
Property damage: 25K
Crop damage: 3K
Reported by: AMATEUR RADIO

Hail in ADAIR, IOWA
From 13-MAY-01 09:08:00 to 13-MAY-01 09:08:00 (CST)
Location: ORIENT
Magnitude: 1.75 
Property damage: 20K
Crop damage: 3K
Reported by: AMATEUR RADIO

Hail in DAVIS, IOWA
From 13-MAY-01 18:24:00 to 13-MAY-01 18:24:00 (CST)
Location: BLOOMFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 09:20:00 to 13-MAY-01 09:20:00 (CST)
Location: ORIENT
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in DECATUR, IOWA
From 13-MAY-01 11:30:00 to 13-MAY-01 11:30:00 (CST)
Location: DECATUR CITY
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in WARREN, IOWA
From 13-MAY-01 10:45:00 to 13-MAY-01 10:45:00 (CST)
Location: MARTENSDALE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 08:55:00 to 13-MAY-01 08:55:00 (CST)
Location: FONTANELLE
Magnitude: 1.75 
Property damage: 15K
Crop damage: 3K
Reported by: EMERGENCY MANAGER

Hail in ADAIR, IOWA
From 13-MAY-01 09:11:00 to 13-MAY-01 09:11:00 (CST)
Location: ORIENT
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: AMATEUR RADIO

Flash Flood in WARREN, IOWA
From 13-MAY-01 11:00:00 to 13-MAY-01 14:45:00 (CST)
Location: COUNTYWIDE
Property damage: 100K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in ADAIR, IOWA
From 13-MAY-01 08:30:00 to 13-MAY-01 08:30:00 (CST)
Location: GREENFIELD
Magnitude: 1.75 
Property damage: 20K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in DAVIS, IOWA
From 13-MAY-01 18:19:00 to 13-MAY-01 18:19:00 (CST)
Location: BLOOMFIELD
Magnitude: 1.25 
Property damage: 7K
Crop damage: 3K
Reported by: UNKNOWN

Hail in CASS, IOWA
From 13-MAY-01 08:02:00 to 13-MAY-01 08:02:00 (CST)
Location: ATLANTIC
Magnitude: 3.00 
Property damage: 75K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Hail in UNION, IOWA
From 13-MAY-01 09:27:00 to 13-MAY-01 09:27:00 (CST)
Location: CRESTON
Magnitude: 1.00 
Property damage: 3K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Hail in WARREN, IOWA
From 13-MAY-01 12:10:00 to 13-MAY-01 12:10:00 (CST)
Location: NORWALK
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Hail in CALHOUN, IOWA
From 13-MAY-01 06:35:00 to 13-MAY-01 06:35:00 (CST)
Location: ROCKWELL CITY
Magnitude: 0.75 
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in WEBSTER, IOWA
From 13-MAY-01 07:15:00 to 13-MAY-01 07:15:00 (CST)
Location: GOWRIE
Magnitude: 1.75 
Property damage: 15K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in CALHOUN, IOWA
From 13-MAY-01 05:58:00 to 13-MAY-01 05:58:00 (CST)
Location: ROCKWELL CITY
Magnitude: 0.88 
Property damage: 3K
Crop damage: 1K
Reported by: LAW ENFORCEMENT

Hail in CASS, IOWA
From 13-MAY-01 07:52:00 to 13-MAY-01 08:02:00 (CST)
Location: ATLANTIC
Magnitude: 1.75 
Property damage: 25K
Crop damage: 10K
Reported by: EMERGENCY MANAGER

Hail in WARREN, IOWA
From 13-MAY-01 11:05:00 to 13-MAY-01 11:05:00 (CST)
Location: ST MARYS
Magnitude: 1.75 
Property damage: 25K
Crop damage: 3K
Reported by: LAW ENFORCEMENT

Hail in ADAIR, IOWA
From 13-MAY-01 09:03:00 to 13-MAY-01 09:03:00 (CST)
Location: GREENFIELD
Magnitude: 1.75 
Property damage: 25K
Crop damage: 2K
Reported by: AMATEUR RADIO

Hail in WARREN, IOWA
From 13-MAY-01 12:13:00 to 13-MAY-01 12:13:00 (CST)
Location: NORWALK
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in CALHOUN, IOWA
From 13-MAY-01 06:20:00 to 13-MAY-01 06:20:00 (CST)
Location: ROCKWELL CITY
Magnitude: 0.88 
Property damage: 2K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 08:50:00 to 13-MAY-01 08:50:00 (CST)
Location: FONTANELLE
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in WARREN, IOWA
From 13-MAY-01 12:20:00 to 13-MAY-01 12:20:00 (CST)
Location: NORWALK
Magnitude: 1.50 
Property damage: 10K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 13-MAY-01 09:20:00 to 13-MAY-01 09:20:00 (CST)
Location: ORIENT
Magnitude: 1.75 
Property damage: 10K
Crop damage: 3K
Reported by: AMATEUR RADIO

Hail in ADAIR, IOWA
From 13-MAY-01 09:05:00 to 13-MAY-01 09:05:00 (CST)
Location: GREENFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Hail in STORY, IOWA
From 13-MAY-01 12:12:00 to 13-MAY-01 12:12:00 (CST)
Location: CAMBRIDGE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Hail in DAVIS, IOWA
From 13-MAY-01 18:21:00 to 13-MAY-01 18:21:00 (CST)
Location: BLOOMFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in WARREN, IOWA
From 13-MAY-01 12:12:00 to 13-MAY-01 12:12:00 (CST)
Location: NORWALK
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Hail in WARREN, IOWA
From 13-MAY-01 12:30:00 to 13-MAY-01 12:30:00 (CST)
Location: INDIANOLA
Magnitude: 1.00 
Property damage: 5K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in DAVIS, IOWA
From 13-MAY-01 18:38:00 to 13-MAY-01 18:38:00 (CST)
Location: BLOOMFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 3K
Reported by: TRAINED SPOTTER