A very dynamic situation set up for the afternoon of the 16th into the early morning hours of the 17th.  An upper level low pressure area lifted northeast across the northern Plains.  A strong upper level jet lifted northeast on the east side of the upper low with wind speeds in the jet in the 80 to 100 kt range.  Meanwhile, a surface cold front approached Iowa from the northwest.  The airmass became quite unstable in front of the cold front as a broad fetch of warm and moist air overspread the state.  High temperatures reached the mid 80s to mid 90s, with dew point readings in the mid 60s to low 70s.  By evening, the lifted index values were in the -3 to -6 C. range with 2000 to 3000 J/kg of CAPE.  Plenty of moisture was available with precipitable water values in the 1.5 to 2 inch range.  The effective shear in the zero to 3 km range was near 60 kts.  Thunderstorms fired very late in the afternoon to the west of the CWA and advanced into Iowa.  Initially, the storms were somewhat discreet, though severe weather remained limited.  Parameters were favorable with the LCL in the 800 to 1200 meter range, CAPE in the -10 to -30 C. layer was around 400 J/kg, and the downdraft CAPE was in the 1000 to 1500 J/kg range.  Large hail was not realized, with spotty reports of hail to nickel size received.  One of the main reasons for the lack of large hail reports is the fact that the freezing level just ahead of the line was 16,800 feet.  As the evening progressed, the storms became more linear and began to produce high winds.  There were numerous reports of winds in excess of 50 MPH all along the line.  In addition several locations reported severe wind speeds in the 60 to 70 MPH range.  The strongest wind occurred in the Fontanelle area of Adair County with a wind gust of 76 MPH.   High winds north of Fontanelle downed 6 power poles and severely damaged the front porch of a house and damaged 2 barns.   For the most part, damage was limited to trees and spotty crop damage.  Thunderstorms trained over parts of western Iowa.  In Cass County, thunderstorms produced from 2 to 4 inches of rain in the Atlantic area, causing urban flooding between 2300 on the 16th and 0100 on the 17th.  Water shot into the air 2 to 3 feet from the storm sewers and one street buckled due to the water pressure.  Damage was around $50,000.

Thunderstorm Wind in CRAWFORD, IOWA
From 16-SEP-06 22:00:00 to 16-SEP-06 22:00:00 (CST)
Location: DELOIT
Magnitude: 52 EG
Property damage: 4K
Reported by: LAW ENFORCEMENT

Hail in KOSSUTH, IOWA
From 16-SEP-06 21:02:00 to 16-SEP-06 21:02:00 (CST)
Location: ALGONA
Magnitude: 0.88 
Property damage: 2K
Crop damage: 10K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CARROLL, IOWA
From 16-SEP-06 22:00:00 to 16-SEP-06 22:00:00 (CST)
Location: TEMPLETON
Magnitude: 52 EG
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CARROLL, IOWA
From 16-SEP-06 22:00:00 to 16-SEP-06 22:00:00 (CST)
Location: TEMPLETON
Magnitude: 57 EG
Property damage: 10K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in CARROLL, IOWA
From 16-SEP-06 22:01:00 to 16-SEP-06 22:01:00 (CST)
Location: DEDHAM
Magnitude: 0.88 
Property damage: 3K
Crop damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Thunderstorm Wind in CARROLL, IOWA
From 16-SEP-06 22:04:00 to 16-SEP-06 22:04:00 (CST)
Location: DEDHAM
Magnitude: 50 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in CARROLL, IOWA
From 16-SEP-06 22:16:00 to 16-SEP-06 22:16:00 (CST)
Location: MANNING
Magnitude: 52 EG
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MADISON, IOWA
From 17-SEP-06 00:40:00 to 17-SEP-06 00:40:00 (CST)
Location: ST CHARLES
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HUMBOLDT, IOWA
From 16-SEP-06 22:10:00 to 16-SEP-06 22:10:00 (CST)
Location: DAKOTA CITY
Magnitude: 57 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in GREENE, IOWA
From 16-SEP-06 22:53:00 to 16-SEP-06 22:53:00 (CST)
Location: JEFFERSON
Magnitude: 50 EG
Property damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in HAMILTON, IOWA
From 17-SEP-06 01:05:00 to 17-SEP-06 01:05:00 (CST)
Location: RANDALL
Magnitude: 57 EG
Property damage: 5K
Crop damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in ADAIR, IOWA
From 16-SEP-06 23:55:00 to 16-SEP-06 23:55:00 (CST)
Location: FONTANELLE
Magnitude: 61 EG
Property damage: 40K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in ADAIR, IOWA
From 16-SEP-06 23:55:00 to 16-SEP-06 23:55:00 (CST)
Location: FONTANELLE
Magnitude: 52 EG
Property damage: 3K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in RINGGOLD, IOWA
From 17-SEP-06 00:15:00 to 17-SEP-06 00:15:00 (CST)
Location: REDDING
Magnitude: 57 EG
Property damage: 20K
Crop damage: 2K
Reported by: NEWSPAPER

Thunderstorm Wind in CRAWFORD, IOWA
From 16-SEP-06 20:55:00 to 16-SEP-06 20:55:00 (CST)
Location: MANILLA
Magnitude: 52 EG
Property damage: 5K
Reported by: NEWSPAPER

Hail in KOSSUTH, IOWA
From 16-SEP-06 20:55:00 to 16-SEP-06 20:55:00 (CST)
Location: ALGONA
Magnitude: 0.88 
Property damage: 3K
Crop damage: 10K
Reported by: AMATEUR RADIO

Hail in KOSSUTH, IOWA
From 16-SEP-06 20:57:00 to 16-SEP-06 20:57:00 (CST)
Location: ALGONA
Magnitude: 0.88 
Property damage: 2K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in HAMILTON, IOWA
From 16-SEP-06 23:10:00 to 16-SEP-06 23:10:00 (CST)
Location: WEBSTER CITY
Magnitude: 0.75 
Crop damage: 5K
Reported by: STORM CHASER

Thunderstorm Wind in FRANKLIN, IOWA
From 16-SEP-06 23:45:00 to 16-SEP-06 23:45:00 (CST)
Location: GENEVA
Magnitude: 50 EG
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CRAWFORD, IOWA
From 16-SEP-06 20:15:00 to 16-SEP-06 20:15:00 (CST)
Location: DENISON
Magnitude: 50 EG
Property damage: 1K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in CALHOUN, IOWA
From 16-SEP-06 21:40:00 to 16-SEP-06 21:40:00 (CST)
Location: JOLLEY
Magnitude: 52 EG
Property damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in CALHOUN, IOWA
From 16-SEP-06 22:20:00 to 16-SEP-06 22:20:00 (CST)
Location: LAKE CITY
Magnitude: 57 EG
Property damage: 5K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POCAHONTAS, IOWA
From 16-SEP-06 21:50:00 to 16-SEP-06 21:50:00 (CST)
Location: LAURENS
Magnitude: 52 EG
Property damage: 10K
Reported by: NEWSPAPER

Thunderstorm Wind in AUDUBON, IOWA
From 16-SEP-06 22:12:00 to 16-SEP-06 22:12:00 (CST)
Location: AUDUBON
Magnitude: 52 EG
Property damage: 1K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in BOONE, IOWA
From 16-SEP-06 23:15:00 to 16-SEP-06 23:15:00 (CST)
Location: BOONE
Magnitude: 52 EG
Property damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Thunderstorm Wind in HAMILTON, IOWA
From 16-SEP-06 23:31:00 to 16-SEP-06 23:31:00 (CST)
Location: WILLIAMS
Magnitude: 62 MG
Property damage: 5K
Crop damage: 10K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in ADAIR, IOWA
From 16-SEP-06 23:51:00 to 16-SEP-06 23:51:00 (CST)
Location: FONTANELLE
Magnitude: 66 MG
Property damage: 10K
Crop damage: 10K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in UNION, IOWA
From 17-SEP-06 00:06:00 to 17-SEP-06 00:06:00 (CST)
Location: CRESTON
Magnitude: 52 EG
Property damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in DALLAS, IOWA
From 17-SEP-06 00:29:00 to 17-SEP-06 00:29:00 (CST)
Location: PERRY
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BOONE, IOWA
From 17-SEP-06 00:47:00 to 17-SEP-06 00:47:00 (CST)
Location: BOONE
Magnitude: 50 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in STORY, IOWA
From 17-SEP-06 01:00:00 to 17-SEP-06 01:00:00 (CST)
Location: STORY CITY
Magnitude: 57 EG
Property damage: 10K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in STORY, IOWA
From 17-SEP-06 01:03:00 to 17-SEP-06 01:03:00 (CST)
Location: AMES
Magnitude: 57 EG
Property damage: 15K
Crop damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in MARION, IOWA
From 17-SEP-06 01:52:00 to 17-SEP-06 01:52:00 (CST)
Location: PELLA
Magnitude: 53 MG
Property damage: 5K
Crop damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in APPANOOSE, IOWA
From 17-SEP-06 02:00:00 to 17-SEP-06 02:00:00 (CST)
Location: CINCINNATI
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER