Strong winds aloft were in place over Iowa with a strong southwest flow of 35 to 55 kts in place through the lower and middle levels of the atmosphere.  A cold front approached Iowa from the west during the afternoon and evening hours.  The airmass was not all that unstable, with limited CAPE available for the event.  Most unstable CAPE values were in the 1000 to 1500 J/kg range with shear values around 45 kts.  There was a decent amount of downdraft CAPE available, in the 1000 to 1200 J/kg range.  Morning convection complicated the weather situation by reducing the solar insulation across the area.  Eastern Iowa did clear out enough to allow temperatures to warm in to the mid 80s, along with dew point temperatures in the mid 60s.  A line of thunderstorms formed along this discontinuity during the last afternoon.  This line lifted northeast quite rapidly, producing high winds as it did.  A strong short wave lifted out of the southern plains during the late afternoon and evening hours.  This in combination with the approaching cold front resulted in a strong line of thunderstorms along the front in western Iowa.  As the storms advanced east, several small bow echo segments and meso-cyclones developed, resulting in high winds for parts of west central into central Iowa.  Both of the lines of storms featured high wind as the mode of severe weather.  Wind gusts were recorded in the 60 to 70 MPH range with the storms as strong winds from aloft mixed into the outflow of the storms.  Several reports of tree and power line damage were received.  One of the storms in Wayne County removed some shingles from a roof of a house and tore off a half sheet of plywood from the chimney.

Thunderstorm Wind in STORY, IOWA
From 18-SEP-07 20:02:00 to 18-SEP-07 20:02:00 (CST-6)
Location: AMES
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Power lines were blown down in two different locations near the city. One set of power lines landed on a Schwans truck.

Thunderstorm Wind in BLACK HAWK, IOWA
From 18-SEP-07 17:30:00 to 18-SEP-07 17:30:00 (CST-6)
Location: LA PORTE CITY
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Tree branches of 8 to 10 inches in diameter were blown down, blocking the road at Iowa and Sycamore.  Reported by KWWL TV.

Thunderstorm Wind in GUTHRIE, IOWA
From 18-SEP-07 19:06:00 to 18-SEP-07 19:06:00 (CST-6)
Location: GUTHRIE CENTER
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Emergency Manager

High winds downed trees, power poles, and lines in Guthrie Center.

Thunderstorm Wind in WAYNE, IOWA
From 18-SEP-07 15:47:00 to 18-SEP-07 15:47:00 (CST-6)
Location: CAMBRIA
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 10.00K
Reported by: Trained Spotter

A 20 inch diameter Ash tree was split in half, along  with several other large tree limbs down in the town of Cambria.  In addition, one 18 inch diameter tree limb was downed.

Thunderstorm Wind in POLK, IOWA
From 18-SEP-07 19:52:00 to 18-SEP-07 19:52:00 (CST-6)
Location: CROCKER
Magnitude: 45.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A 30 inch diameter tree was blown over.

Thunderstorm Wind in GUTHRIE, IOWA
From 18-SEP-07 19:10:00 to 18-SEP-07 19:10:00 (CST-6)
Location: MENLO
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Power lines blown down in Menlo, power was out on the west side of town.

Thunderstorm Wind in WAYNE, IOWA
From 18-SEP-07 16:00:00 to 18-SEP-07 16:00:00 (CST-6)
Location: CORYDON
Magnitude: 65.00 EG
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A 4 foot diameter tree uprooted, along with several 10 to  20 inch tree limbs being blown down.  This included many hard wood trees down in the town of Corydon. One house had several shingles and a half sheet of plywood blown off at the chimney and one large tree down.

Thunderstorm Wind in DALLAS, IOWA
From 18-SEP-07 19:30:00 to 18-SEP-07 19:30:00 (CST-6)
Location: PERRY
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous 6 to 10 inch tree limbs were blown down in Perry.  A tree blocked a road in town. Winds blew down street barricades, damaging them.

Thunderstorm Wind in POLK, IOWA
From 18-SEP-07 20:00:00 to 18-SEP-07 20:00:00 (CST-6)
Location: WINDSOR HGTS
Magnitude: 50.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Two large trees down were blown down in Windsor Park. This report was relayed by KCCI TV.

Thunderstorm Wind in GUTHRIE, IOWA
From 18-SEP-07 18:58:00 to 18-SEP-07 18:58:00 (CST-6)
Location: CASEY
Magnitude: 56.00 MG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Mesonet

Report from schoolnet site SADI4.

Thunderstorm Wind in POWESHIEK, IOWA
From 18-SEP-07 16:50:00 to 18-SEP-07 16:50:00 (CST-6)
Location: MONTEZUMA
Magnitude: 60.00 MG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Trained Spotter

A trained spotter measured this wind gust and reported tree limb damage.

Thunderstorm Wind in MARION, IOWA
From 18-SEP-07 16:05:00 to 18-SEP-07 16:05:00 (CST-6)
Location: PLEASANTVILLE
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

High winds downed power lines.

Thunderstorm Wind in AUDUBON, IOWA
From 18-SEP-07 18:32:00 to 18-SEP-07 18:32:00 (CST-6)
Location: AUDUBON
Magnitude: 56.00 MG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind report was from the Audubon Community schoolnet. ID SAUI4.

Thunderstorm Wind in GREENE, IOWA
From 18-SEP-07 19:20:00 to 18-SEP-07 19:20:00 (CST-6)
Location: DANA
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winds were estimated 60 to 65 MPH.

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

An ISU Meteorology professor reports at least 60 MPH wind on far north side of Ames.

Thunderstorm Wind in WAYNE, IOWA
From 18-SEP-07 15:44:00 to 18-SEP-07 15:44:00 (CST-6)
Location: CORYDON
Magnitude: 60.00 MG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Mesonet

Winds were reported from KCCI TV schoolnet site.

Thunderstorm Wind in AUDUBON, IOWA
From 18-SEP-07 18:38:00 to 18-SEP-07 18:38:00 (CST-6)
Location: GARDNER
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 2.00K
Reported by: Trained Spotter

Thunderstorm Wind in MARION, IOWA
From 18-SEP-07 15:55:00 to 18-SEP-07 15:55:00 (CST-6)
Location: PLEASANTVILLE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Thunderstorm Wind in DALLAS, IOWA
From 18-SEP-07 19:35:00 to 18-SEP-07 19:35:00 (CST-6)
Location: BOUTON
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in DALLAS, IOWA
From 18-SEP-07 19:33:00 to 18-SEP-07 19:33:00 (CST-6)
Location: BOUTON
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in STORY, IOWA
From 18-SEP-07 20:01:00 to 18-SEP-07 20:01:00 (CST-6)
Location: SLATER
Magnitude: 45.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A 2 foot diameter branch fell off of a tree and blocked highway 210.

Thunderstorm Wind in WAYNE, IOWA
From 18-SEP-07 15:50:00 to 18-SEP-07 15:50:00 (CST-6)
Location: CORYDON
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Large trees were blown over into the road in south Corydon.