An intense spring storm took shape over the central U.S. during the day on the 10th.  The surface low formed over the southern Rockies the previous night and moved into Kansas during the day, then moved into southwest Iowa  during the evening of the 10th.  The upper level low pressure became nearly stacked by the morning of the 11th.  For the most part, Iowa remained on the cold side of the system through the day.  During the late afternoon, as the low lifted northeast, a warm front extending east out of the low pushed north into the state.  South of the front, temperatures were in the 60s to low 70s with dew point temperatures in the upper 50s to low 60s.  The atmosphere became unstable with CAPE in the 500 to 1000 J/kg range by evening across southern Iowa.  A strong low level jet was in place with wind speeds around 60 kts.  With the strong winds, both in the low levels and aloft, the effective shear was quite high in the 40 to 55 kt range.  The LCL was quite low with the rainfall that continued through the day and was around 500 meters during the event.  A fair share of the CAPE was in the -10 to -30 C. layer of the atmosphere with 300 J/kg available.  This was a classic low top convection case with the upper low and dry line approaching from the southwest.  The freezing level was very low across the CWA, sloping from around 6000 feet in the Omaha, NE area, to 9700 feet in the Davenport, IA area.  Lifted indices were around +4, however on the warm side of the warm front they were in the -2 to -4 C. range.  The warm front surged north rapidly into Iowa during the evening, pushing from the Iowa-Missouri border into central Iowa in about 4 hours.  Thunderstorms initially formed in an arc from northeast Kansas into western Missouri.  The storms lifted north-northeast at 50 to 60 MPH.  Rotation was noted in nearly all of the storms with tornadoes produced by some.  One of the stronger storms was a cyclic tornado producer and moved out of northern Missouri into Wayne and Appanoose Counties.  It continued northeast across Monroe, into Mahaska, and then Poweshiek Counties.  Two small tornadoes touched down in Wayne County.  They were only on the ground briefly and caused no damage as they were in open country.  Wind speeds on these tornadoes were estimated at 75 MPH.  A tornado touched down in Appanoose County near Seymour and produced winds of 90 to 100 mph.  Damage from the tornado started about 1 mile south of the intersection of highway J46 and 105th Avenue in far western Appanoose County.  The tornado moved rapidly northeast producing primarily tree damage across rural countryside.  The tornado hit a residence on the southern side of Highway J46, producing EF1 damage to the house and various outbuildings. In addition, a large utility pole was pulled 4 feet south before listing severely to the north.  The tornado and debris continue for close to another mile before ending. The storm moved north into the Iconium area.  It was observed on southern shore of Rathbun Reservoir before traversing the lake and entering into the Antler Acres Trailer park subdivision.  The tornado produced much roof and soffit damage, as well as window damage to many of the homes.    However, one mobile home was lifted and shifted several feet before tie downs held it in place.  The worst damage was to a mobile home which was flipped on its side after the tie downs were ripped out of the ground.  An additional outbuilding about one quarter of a mile to the northeast was badly damaged as well.  The tornado moved nearly to the Monroe County border before lifting.  It set down again in Mahaska County and moved northeast to the southwest of Oskaloosa.  Scattered damage occurred along its path with damage done to fuel pumps at a gas station in the Oskaloosa area as the parent storm passed.  There was also considerable wind damage in the area caused by the RFD.  The same storm moved into Poweshiek County.  The tornado redeveloped just northeast of Barnes City and moved northeast.  Several power lines were downed along with structural and shingle damage to houses. In addition, storm spotters reported some grain bin damage, and road signs were pulled out of the ground.  One mobile home was ripped from its foundation in the 1900 block of Highway 85.  Another brief touchdown occurred a short time later in Poweshiek County.  In addition to the tornadic storms, several of the storms produced high winds and hail.  The hail was generally no larger than an inch in diameter, with most of it around nickel size.  The largest hail was west of Centerville in Appanoose County where one inch diameter hail fell.  There were several reports of high winds, though much of the damage was relatively minor.  High winds in Oskaloosa caused some roof damage and took down power poles.  Damage was also reported to fuel pumps in Oskaloosa.  In Poweshiek County, two barns were blown down and portions of a roof were peeled off at a farmstead east of Brooklyn.  In addition, siding was torn off of the house and windows were blown out.  These were some of the more substantial reports.  Late in the event, additional thunderstorms formed over northern Missouri.  They produced 58 MPH winds in the Lamoni area.

Thunderstorm Wind in MAHASKA, IOWA
From 10-APR-08 16:54:00 to 10-APR-08 16:54:00 (CST-6)
Location: UNIVERSITY PARK
Magnitude: 57.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Two trees were uprooted.  Sign damage occurred from the high wind and a power pole was leaning.  Minor damage to the exterior of a building. Damage was also reported to fuel pumps and a store front in Oskaloosa.

Thunderstorm Wind in DECATUR, IOWA
From 10-APR-08 20:39:00 to 10-APR-08 20:39:00 (CST-6)
Location: LAMONI
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in MONROE, IOWA
From 10-APR-08 16:34:00 to 10-APR-08 16:34:00 (CST-6)
Location: AVERY
Magnitude: 52.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An old schoolhouse was destroyed.  Building was in poor shape before the storm hit.

Thunderstorm Wind in MONROE, IOWA
From 10-APR-08 16:35:00 to 10-APR-08 16:35:00 (CST-6)
Location: AVERY
Magnitude: 57.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A Morton building was severely damaged.  Some shingles were blown off of a house and a small grain bin was destroyed.

Thunderstorm Wind in MAHASKA, IOWA
From 10-APR-08 16:55:00 to 10-APR-08 16:55:00 (CST-6)
Location: UNIVERSITY PARK
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Several trees were damaged and shingles were blown off of a house.

Hail in APPANOOSE, IOWA
From 10-APR-08 17:34:00 to 10-APR-08 17:34:00 (CST-6)
Location: RATHBUN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in CLARKE, IOWA
From 10-APR-08 18:14:00 to 10-APR-08 18:14:00 (CST-6)
Location: OSCEOLA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Penny size hail occurred 3 miles southeast of Osceola.

Hail in JASPER, IOWA
From 10-APR-08 19:28:00 to 10-APR-08 19:28:00 (CST-6)
Location: NEWTON MUNI ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in GRUNDY, IOWA
From 10-APR-08 19:44:00 to 10-APR-08 19:44:00 (CST-6)
Location: BEAMAN
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tornado in APPANOOSE, IOWA
From 10-APR-08 15:57:00 to 10-APR-08 15:59:00 (CST-6)
Location: JEROME
Tornado F-scale: EF1
Property damage: 75.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Law enforcement reported the tornado on the ground west of Numa, moving northeast.

Tornado in APPANOOSE, IOWA
From 10-APR-08 16:10:00 to 10-APR-08 16:13:00 (CST-6)
Location: GRIFFINSVILLE
Tornado F-scale: EF1
Property damage: 75.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Law enforcement reported a tornado near Monrovia moving northeast with damage to a garage and house.

Tornado in MAHASKA, IOWA
From 10-APR-08 16:43:00 to 10-APR-08 16:46:00 (CST-6)
Location: TRUAX
Tornado F-scale: EF1
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Shingles were removed from the roof of a house.  An outbuilding was damaged and the top of an outbuilding was crushed.  Damage was done to structures on the west side of Oskaloosa from the storm after the tornado had lifted.  Intermittent track with rain wrapped tornado and considerable RFD wind damage.

Tornado in POWESHIEK, IOWA
From 10-APR-08 17:21:00 to 10-APR-08 17:29:00 (CST-6)
Location: DEEP RIVER
Tornado F-scale: EF1
Property damage: 100.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A farmstead had 2 barns blown down.  The farmstead had portions of the roof peeled off with siding torn off and windows blown out.

Tornado in WAYNE, IOWA
From 10-APR-08 15:33:00 to 10-APR-08 15:34:00 (CST-6)
Location: LINEVILLE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Only a brief tornado touchdown with no significant damage.

Tornado in WAYNE, IOWA
From 10-APR-08 15:49:00 to 10-APR-08 15:50:00 (CST-6)
Location: CAMBRIA
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A brief touchdown in open country was observed with no damage.

Tornado in POWESHIEK, IOWA
From 10-APR-08 17:36:00 to 10-APR-08 17:38:00 (CST-6)
Location: CARNFORTH
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Damage to a home and outbuildings.  Trees were uprooted and road signs pulled out of the ground.  Damage path was about 2 miles long.

Thunderstorm Wind in WAYNE, IOWA
From 10-APR-08 15:52:00 to 10-APR-08 15:52:00 (CST-6)
Location: GENOA
Magnitude: 65.00 EG
Property damage: 40.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Damage was done to a metal building.

Thunderstorm Wind in APPANOOSE, IOWA
From 10-APR-08 15:53:00 to 10-APR-08 15:53:00 (CST-6)
Location: NUMA
Magnitude: 65.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Power poles were blown down.

Funnel Cloud in LUCAS, IOWA
From 10-APR-08 16:00:00 to 10-APR-08 16:00:00 (CST-6)
Location: CHARITON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A funnel cloud was reported 1 miles west of Chariton.

Funnel Cloud in MONROE, IOWA
From 10-APR-08 16:16:00 to 10-APR-08 16:16:00 (CST-6)
Location: MELROSE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Funnel Cloud in MONROE, IOWA
From 10-APR-08 16:38:00 to 10-APR-08 16:38:00 (CST-6)
Location: AVERY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported a funnel cloud down to the tree line about 3 miles west-southwest of Eddyville.  The storm was moving north-northeast very rapidly.

Hail in MAHASKA, IOWA
From 10-APR-08 17:02:00 to 10-APR-08 17:02:00 (CST-6)
Location: LACEY
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported nickel to quarter size hail 3 miles south of New Sharon.

Hail in APPANOOSE, IOWA
From 10-APR-08 17:24:00 to 10-APR-08 17:24:00 (CST-6)
Location: SUNSHINE
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement