Several boundaries were in position across the state with the main
boundary being that left from the previous nights convection from
northwest into east central Iowa.  At the same time, a cold front
approached the state from the northwest while low pressure developed
over eastern Nebraska.  The atmosphere became very unstable by the early
afternoon hours with CAPE values in the 3000 to 4500 J/kg range and
lifted indices falling to between -7 and -10 C.  Shear across the north
half of Iowa was in the 30 to 40 kt range.  During the afternoon,
temperatures rose into the upper 80s to mid 90s, as dew point readings
rebounded in to the mid to upper 70s along the boundary.  Thunderstorms
erupted by mid afternoon with a large area of thunderstorms moving from
northwest into parts of north central and eventually in to east central
Iowa.  The main mode of severe weather was high winds.  There was
between 900 and 1100 J/kg of DCAPE available with fairly strong winds in
the mid levels.  Reports of downed trees and power lines were numerous
with wind gust reaching 70 MPH or more with some of the stronger
storms.  There was little in the way of hail reported, though pea to
small marble size hail was common.  The available cape in the hail
layer, -10 to -30 C. layer of the atmosphere, was significant in the 400
to 600 J/kg range, but the freezing level was very high.  Typical of mid
July, the freezing level was between 14,000 and 15,000 feet, which
limited hail production.  The storms moved east-southeast at 35 to 45
MPH for the most part with the first round exiting the DMX CWA by early
evening.  Thunderstorms began to redevelop during the evening.  One of the storms produced penny size hail in the Marshalltown area.

Thunderstorm Wind in STORY, IOWA
From 18-JUL-07 17:00:00 to 18-JUL-07 17:00:00 (CST-6)
Location: IOWA CENTER
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in WEBSTER, IOWA
From 18-JUL-07 15:53:00 to 18-JUL-07 15:53:00 (CST-6)
Location: CALLENDER
Magnitude: 57.00 EG
Property damage: 20.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Thunderstorm Wind in HARDIN, IOWA
From 18-JUL-07 16:39:00 to 18-JUL-07 16:39:00 (CST-6)
Location: ELDORA
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm Wind in STORY, IOWA
From 18-JUL-07 16:47:00 to 18-JUL-07 16:47:00 (CST-6)
Location: ZEARING
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Thunderstorm Wind in GRUNDY, IOWA
From 18-JUL-07 17:15:00 to 18-JUL-07 17:15:00 (CST-6)
Location: GRUNDY CENTER
Magnitude: 57.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in MARSHALL, IOWA
From 18-JUL-07 21:05:00 to 18-JUL-07 21:05:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: COOP Observer

Thunderstorm Wind in GRUNDY, IOWA
From 18-JUL-07 17:15:00 to 18-JUL-07 17:15:00 (CST-6)
Location: MORRISON
Magnitude: 61.00 EG
Property damage: 20.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Thunderstorm Wind in HAMILTON, IOWA
From 18-JUL-07 16:18:00 to 18-JUL-07 16:18:00 (CST-6)
Location: WILLIAMS
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in CALHOUN, IOWA
From 18-JUL-07 15:22:00 to 18-JUL-07 15:22:00 (CST-6)
Location: POMEROY
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorm Wind in KOSSUTH, IOWA
From 18-JUL-07 15:00:00 to 18-JUL-07 15:00:00 (CST-6)
Location: BANCROFT
Magnitude: 57.00 EG
Property damage: 15.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Thunderstorm Wind in GRUNDY, IOWA
From 18-JUL-07 16:50:00 to 18-JUL-07 16:50:00 (CST-6)
Location: WELLSBURG
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Thunderstorm Wind in WEBSTER, IOWA
From 18-JUL-07 15:53:00 to 18-JUL-07 15:53:00 (CST-6)
Location: CALLENDER
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in HUMBOLDT, IOWA
From 18-JUL-07 15:31:00 to 18-JUL-07 15:31:00 (CST-6)
Location: DAKOTA CITY
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 5.00K
Reported by: Amateur Radio

Thunderstorm Wind in HAMILTON, IOWA
From 18-JUL-07 16:20:00 to 18-JUL-07 16:20:00 (CST-6)
Location: BLAIRSBURG
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in WRIGHT, IOWA
From 18-JUL-07 16:16:00 to 18-JUL-07 16:16:00 (CST-6)
Location: EAGLE GROVE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in HARDIN, IOWA
From 18-JUL-07 16:35:00 to 18-JUL-07 16:35:00 (CST-6)
Location: RADCLIFFE
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in GRUNDY, IOWA
From 18-JUL-07 17:00:00 to 18-JUL-07 17:00:00 (CST-6)
Location: HOLLAND
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in MARSHALL, IOWA
From 18-JUL-07 17:07:00 to 18-JUL-07 17:07:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in GRUNDY, IOWA
From 18-JUL-07 17:15:00 to 18-JUL-07 17:15:00 (CST-6)
Location: REINBECK
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in HUMBOLDT, IOWA
From 18-JUL-07 15:32:00 to 18-JUL-07 15:32:00 (CST-6)
Location: DAKOTA CITY
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 25.00K
Reported by: Trained Spotter

Thunderstorm Wind in CALHOUN, IOWA
From 18-JUL-07 15:30:00 to 18-JUL-07 15:30:00 (CST-6)
Location: MANSON
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in CALHOUN, IOWA
From 18-JUL-07 15:33:00 to 18-JUL-07 15:33:00 (CST-6)
Location: MANSON
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Thunderstorm Wind in MARSHALL, IOWA
From 18-JUL-07 17:06:00 to 18-JUL-07 17:06:00 (CST-6)
Location: STATE CENTER
Magnitude: 65.00 EG
Property damage: 30.00K
Crop damage: 50.00K
Reported by: Emergency Manager

Thunderstorm Wind in POWESHIEK, IOWA
From 18-JUL-07 18:20:00 to 18-JUL-07 18:20:00 (CST-6)
Location: MONTEZUMA
Magnitude: 56.00 MG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Thunderstorm Wind in TAMA, IOWA
From 18-JUL-07 17:15:00 to 18-JUL-07 17:15:00 (CST-6)
Location: BUCKINGHAM
Magnitude: 57.00 EG
Property damage: 20.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Thunderstorm Wind in BLACK HAWK, IOWA
From 18-JUL-07 17:25:00 to 18-JUL-07 17:25:00 (CST-6)
Location: LA PORTE CITY ARPT
Magnitude: 56.00 EG
Property damage: 30.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Thunderstorm Wind in POWESHIEK, IOWA
From 18-JUL-07 17:40:00 to 18-JUL-07 17:40:00 (CST-6)
Location: GRINNELL ARPT
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in TAMA, IOWA
From 18-JUL-07 17:11:00 to 18-JUL-07 17:11:00 (CST-6)
Location: GARWIN
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 3.00K
Reported by: Law Enforcement

Thunderstorm Wind in MARSHALL, IOWA
From 18-JUL-07 17:18:00 to 18-JUL-07 17:18:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 52.00 MG
Property damage: 3.00K
Crop damage: 50.00K
Reported by: Mesonet

Thunderstorm Wind in SAC, IOWA
From 18-JUL-07 22:05:00 to 18-JUL-07 22:05:00 (CST-6)
Location: ODEBOLT
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Thunderstorm Wind in WEBSTER, IOWA
From 18-JUL-07 15:45:00 to 18-JUL-07 15:45:00 (CST-6)
Location: FT DODGE
Magnitude: 52.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Newspaper