Another round of elevated convection moved into Iowa shortly after sunrise for the second day in a row.  The synoptic situation was very much unchanged from the morning before.  A stationary front extended from the Nebraska Panhandle into far northwest Iowa and into Wisconsin.  Aloft a fast west to northwest flow of air was in place as the sub-tropical ridge aloft was firmly in place over the central U.S.  Dew Point temperatures were in the low to mid 70s at sunrise, making for a very unstable airmass.  The airmass was capped so convection was not able to initiate from the surface in spite of a weak boundary which was left across Iowa from the previous days convection.  As the thunderstorms moved into Iowa, a small cluster  of storms raced east at over 50 MPH in what was a mini Derecho.  As the storms moved through western Iowa, Sac County was the first to be hit.  Seventy MPH winds downed several trees in the southern part of the county with reports of one out building being destroyed.  The storms weakened after that until they reached central Iowa.  Deeper moisture aid in the intensification of the storms in Boone County.  High winds moved through Boon with several trees being blown down in town.  The high winds continued as the storm moved through Story County.  Most areas reported winds around 50 MPH, however the storm began to increase as it moved into the Nevada area.  Several large tree limbs were downed and a 14 inch diameter pine tree was snapped off.  Winds of 70 to 75 MPH were reported with the storm as it moved into the town of Marshalltown in Marshall County.  Quite a bit of damage was reported to trees in the town itself.  High winds continued with the storm as it raced across Tama County as well.  Winds of 70 to 75 MPH were reported in the towns of Tama and Dysart, causing considerable tree and power line damage.

Thunderstorm Wind in MARSHALL, IOWA
From 08-JUL-01 09:40:00 to 08-JUL-01 09:40:00 (CST)
Location: MARSHALLTOWN
Magnitude: 65 E
Property damage: 15K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in BOONE, IOWA
From 08-JUL-01 08:45:00 to 08-JUL-01 08:45:00 (CST)
Location: BOONE
Magnitude: 50 E
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 08-JUL-01 09:00:00 to 08-JUL-01 09:00:00 (CST)
Location: NEVADA
Magnitude: 50 E
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in TAMA, IOWA
From 08-JUL-01 10:25:00 to 08-JUL-01 10:25:00 (CST)
Location: TAMA
Magnitude: 61 E
Property damage: 10K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in MARSHALL, IOWA
From 08-JUL-01 09:15:00 to 08-JUL-01 09:15:00 (CST)
Location: STATE CENTER
Magnitude: 61 E
Property damage: 10K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in TAMA, IOWA
From 08-JUL-01 10:10:00 to 08-JUL-01 10:10:00 (CST)
Location: DYSART
Magnitude: 61 E
Property damage: 10K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in SAC, IOWA
From 08-JUL-01 07:00:00 to 08-JUL-01 07:15:00 (CST)
Location: CARNARVON
Magnitude: 61 E
Property damage: 15K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MARSHALL, IOWA
From 08-JUL-01 09:35:00 to 08-JUL-01 09:35:00 (CST)
Location: MARSHALLTOWN
Magnitude: 61 E
Property damage: 10K
Crop damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MARSHALL, IOWA
From 08-JUL-01 09:25:00 to 08-JUL-01 09:25:00 (CST)
Location: STATE CENTER
Magnitude: 61 E
Property damage: 10K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 08-JUL-01 08:25:00 to 08-JUL-01 08:25:00 (CST)
Location: BOONE
Magnitude: 52 E
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in TAMA, IOWA
From 08-JUL-01 09:50:00 to 08-JUL-01 09:50:00 (CST)
Location: TAMA
Magnitude: 65 E
Property damage: 15K
Crop damage: 5K
Reported by: LAW ENFORCEMENT