An unseasonably warm airmass overspread Iowa during the day on the 13th.  Maximum temperatures reached the mid 80s to low 90s across the state.  Dew point readings were in the upper 50s to low 60s.  A weak frontal boundary extending north-northeast to south-southwest advanced into the state during the late afternoon.  The airmass had become very unstable with Lifted Indices in the -5 to -8 range.  CAPE values reached 3500 by the late afternoon hours.  Thunderstorms erupted late in the afternoon and became severe very quickly.  The main mode of severe weather with the storms was large hail.  The freezing level was around 12,300 feet.  Though quite high for mid April, it was easily low enough to make hail production easy.  Several of the storms exhibited the structure of a tornadic supercell.  The LCL was quite high however, at around 7300 feet.  This limited the development of tornadoes somewhat.  One tornado touched down in Tama County, northeast of Toledo.  The tornado was on the ground briefly and touched down in an open field.  No damage was reported with the tornado.  Many of the storms produced large hail.  There were numerous reports of one to two inch diameter hail.  A couple of the storms produced very large hail.  Hail of tennis ball to base ball size was reported in Hardin County south of Radcliffe and southwest of Hubbard.  The same storm that produced the brief tornado touchdown in Tama County also produced hail of two and one half inches in diameter east of the Traer area.

Hail in GRUNDY, IOWA
From 13-APR-06 17:56:00 to 13-APR-06 17:56:00 (CST)
Location: GRUNDY CENTER
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in GRUNDY, IOWA
From 13-APR-06 18:30:00 to 13-APR-06 18:30:00 (CST)
Location: CONRAD
Magnitude: 1.75 
Property damage: 20K
Reported by: COOP STATION

Hail in TAMA, IOWA
From 13-APR-06 18:30:00 to 13-APR-06 18:30:00 (CST)
Location: GARWIN
Magnitude: 1.75 
Property damage: 20K
Reported by: COOP STATION

Hail in FRANKLIN, IOWA
From 13-APR-06 18:30:00 to 13-APR-06 18:30:00 (CST)
Location: ACKLEY
Magnitude: 1.25 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in TAMA, IOWA
From 13-APR-06 18:10:00 to 13-APR-06 18:10:00 (CST)
Location: TRAER
Magnitude: 2.00 
Property damage: 15K
Reported by: NEWSPAPER

Hail in TAMA, IOWA
From 13-APR-06 18:15:00 to 13-APR-06 18:15:00 (CST)
Location: DYSART
Magnitude: 1.00 
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 13-APR-06 17:18:00 to 13-APR-06 17:18:00 (CST)
Location: ELDORA
Magnitude: 0.88 
Property damage: 2K
Reported by: EMERGENCY MANAGER

Hail in TAMA, IOWA
From 13-APR-06 18:15:00 to 13-APR-06 18:15:00 (CST)
Location: TRAER
Magnitude: 1.75 
Property damage: 25K
Reported by: TRAINED SPOTTER

Hail in TAMA, IOWA
From 13-APR-06 18:17:00 to 13-APR-06 18:17:00 (CST)
Location: TRAER
Magnitude: 2.50 
Property damage: 20K
Reported by: TRAINED SPOTTER

Tornado in TAMA, IOWA
From 13-APR-06 18:10:00 to 13-APR-06 18:10:00 (CST)
Location: TOLEDO
Tornado F-scale: F0
Reported by: GENERAL PUBLIC

Tornado touched down briefly in open fields northeast of Tama.  No damage occurred.

Hail in HARDIN, IOWA
From 13-APR-06 18:12:00 to 13-APR-06 18:12:00 (CST)
Location: IOWA FALLS
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in TAMA, IOWA
From 13-APR-06 18:36:00 to 13-APR-06 18:36:00 (CST)
Location: GARWIN
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in BLACK HAWK, IOWA
From 13-APR-06 18:25:00 to 13-APR-06 18:25:00 (CST)
Location: WATERLOO
Magnitude: 1.00 
Property damage: 10K
Reported by: TRAINED SPOTTER

Hail in BLACK HAWK, IOWA
From 13-APR-06 18:25:00 to 13-APR-06 18:25:00 (CST)
Location: WATERLOO
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in HAMILTON, IOWA
From 13-APR-06 17:07:00 to 13-APR-06 17:07:00 (CST)
Location: JEWELL
Magnitude: 0.75 
Reported by: AMATEUR RADIO

Hail in HAMILTON, IOWA
From 13-APR-06 17:14:00 to 13-APR-06 17:14:00 (CST)
Location: RANDALL
Magnitude: 1.00 
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in HAMILTON, IOWA
From 13-APR-06 17:14:00 to 13-APR-06 17:14:00 (CST)
Location: ELLSWORTH
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 17:17:00 to 13-APR-06 17:17:00 (CST)
Location: IOWA FALLS
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in TAMA, IOWA
From 13-APR-06 18:09:00 to 13-APR-06 18:09:00 (CST)
Location: TRAER
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 18:10:00 to 13-APR-06 18:10:00 (CST)
Location: IOWA FALLS
Magnitude: 1.00 
Property damage: 5K
Reported by: AMATEUR RADIO

Hail in HAMILTON, IOWA
From 13-APR-06 17:04:00 to 13-APR-06 17:04:00 (CST)
Location: JEWELL
Magnitude: 1.75 
Property damage: 20K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 13-APR-06 17:56:00 to 13-APR-06 17:56:00 (CST)
Location: STEAMBOAT ROCK
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in GRUNDY, IOWA
From 13-APR-06 17:37:00 to 13-APR-06 17:37:00 (CST)
Location: CONRAD
Magnitude: 1.50 
Property damage: 15K
Reported by: AMATEUR RADIO

Hail in HAMILTON, IOWA
From 13-APR-06 17:01:00 to 13-APR-06 17:01:00 (CST)
Location: JEWELL
Magnitude: 0.88 
Property damage: 2K
Reported by: LAW ENFORCEMENT

Hail in HAMILTON, IOWA
From 13-APR-06 16:56:00 to 13-APR-06 16:56:00 (CST)
Location: STANHOPE
Magnitude: 1.00 
Property damage: 3K
Reported by: AMATEUR RADIO

Hail in HAMILTON, IOWA
From 13-APR-06 16:44:00 to 13-APR-06 16:44:00 (CST)
Location: STRATFORD
Magnitude: 1.75 
Property damage: 10K
Reported by: TRAINED SPOTTER

Hail in HAMILTON, IOWA
From 13-APR-06 16:57:00 to 13-APR-06 16:57:00 (CST)
Location: STANHOPE
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 17:44:00 to 13-APR-06 17:44:00 (CST)
Location: NEW PROVIDENCE
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 17:31:00 to 13-APR-06 17:31:00 (CST)
Location: RADCLIFFE
Magnitude: 2.75 
Property damage: 25K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 13-APR-06 17:32:00 to 13-APR-06 17:32:00 (CST)
Location: HUBBARD
Magnitude: 2.00 
Property damage: 25K
Reported by: BROADCAST MEDIA

Hail in HAMILTON, IOWA
From 13-APR-06 16:50:00 to 13-APR-06 16:50:00 (CST)
Location: STANHOPE
Magnitude: 1.00 
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 13-APR-06 17:38:00 to 13-APR-06 17:38:00 (CST)
Location: HUBBARD
Magnitude: 1.50 
Property damage: 10K
Reported by: AMATEUR RADIO

Hail in TAMA, IOWA
From 13-APR-06 17:52:00 to 13-APR-06 17:52:00 (CST)
Location: TRAER
Magnitude: 1.75 
Property damage: 10K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 17:42:00 to 13-APR-06 17:42:00 (CST)
Location: STEAMBOAT ROCK
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in BUTLER, IOWA
From 13-APR-06 17:30:00 to 13-APR-06 17:30:00 (CST)
Location: APLINGTON
Magnitude: 0.75 
Reported by: GENERAL PUBLIC

Hail in MARSHALL, IOWA
From 13-APR-06 18:00:00 to 13-APR-06 18:00:00 (CST)
Location: LISCOMB
Magnitude: 0.88 
Property damage: 3K
Reported by: AMATEUR RADIO

Hail in BLACK HAWK, IOWA
From 13-APR-06 18:06:00 to 13-APR-06 18:06:00 (CST)
Location: HUDSON
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in WEBSTER, IOWA
From 13-APR-06 16:43:00 to 13-APR-06 16:43:00 (CST)
Location: DAYTON
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in FRANKLIN, IOWA
From 13-APR-06 17:25:00 to 13-APR-06 17:25:00 (CST)
Location: ACKLEY
Magnitude: 1.75 
Property damage: 10K
Reported by: TRAINED SPOTTER

Hail in WRIGHT, IOWA
From 13-APR-06 17:26:00 to 13-APR-06 17:26:00 (CST)
Location: EAGLE GROVE
Magnitude: 0.88 
Property damage: 2K
Reported by: NEWSPAPER

Hail in GRUNDY, IOWA
From 13-APR-06 17:26:00 to 13-APR-06 17:26:00 (CST)
Location: GRUNDY CENTER
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 13-APR-06 17:27:00 to 13-APR-06 17:27:00 (CST)
Location: GARDEN CITY
Magnitude: 0.75 
Reported by: GENERAL PUBLIC

Hail in HARDIN, IOWA
From 13-APR-06 17:27:00 to 13-APR-06 17:27:00 (CST)
Location: HUBBARD
Magnitude: 1.75 
Property damage: 10K
Reported by: AMATEUR RADIO

Hail in GRUNDY, IOWA
From 13-APR-06 18:37:00 to 13-APR-06 18:37:00 (CST)
Location: CONRAD
Magnitude: 1.50 
Property damage: 15K
Reported by: AMATEUR RADIO

Hail in GRUNDY, IOWA
From 13-APR-06 18:52:00 to 13-APR-06 18:52:00 (CST)
Location: GRUNDY CENTER
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in GRUNDY, IOWA
From 13-APR-06 19:04:00 to 13-APR-06 19:04:00 (CST)
Location: GRUNDY CENTER
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in STORY, IOWA
From 13-APR-06 17:25:00 to 13-APR-06 17:25:00 (CST)
Location: MC CALLSBURG
Magnitude: 1.75 
Property damage: 15K
Reported by: GENERAL PUBLIC

Hail in HARDIN, IOWA
From 13-APR-06 17:29:00 to 13-APR-06 17:29:00 (CST)
Location: ELDORA
Magnitude: 1.00 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in GRUNDY, IOWA
From 13-APR-06 17:29:00 to 13-APR-06 17:29:00 (CST)
Location: WELLSBURG
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in GRUNDY, IOWA
From 13-APR-06 17:29:00 to 13-APR-06 17:29:00 (CST)
Location: GRUNDY CENTER
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER