A strong upper low moved into the central United States.  Surface low pressure was located over northwest Kansas into southwest Nebraska during the late afternoon.  A warm front extended from the low across northern Missouri into southern Illinois.  A strong push of moisture took place south of the front with dewpoints rising into the upper 50s to low 60s.  Precipitable water values increased to around 1.3 inches.  The freezing level was relatively low, around 11,000 feet.  The atmosphere was strongly sheared with 50 to 60 kts of shear available.  By the afternoon, the atmosphere became unstable with 1000 to 2000 J.kg of CAPE available.  Downdraft CAPE was quite high in the 700 to 1000 J/kg.  CAPE in the -10 to -30 C layer of the atmosphere was around 200 J/kg.  A strong line of thunderstorms formed on the east edge of the dry slot as it pushed into Iowa.  Thunderstorms remained below severe levels through the morning, however, they intensified as the moved into south central and southeast Iowa.  One tornado touched down in Wapello County before racing northward into Keokuk County.  There were numerous reports of high winds as the line progressed east with winds of 60 to 70 MPH.  Numerous trees were blown down by the high winds.  The roof was taken off of a family medical center in northeast Oskaloosa in Mahaska County.  Major structural damage was reported on a farmstead west of Ottumwa in Wapello County with outbuildings damaged and roof damage to the porch of the farmstead.  Windows were blown out of cars and roofs were blown from buildings on a farmstead east of Cincinnati in Appanoose County.  Ten people were injured, some requiring hospitalization, on the south side of Ottumwa. At least four of the ten were injured when thunderstorms winds lifted debris at an auction on the south side of the city.  One injury was reported in Appanoose County when a woman was struck by debris lifted by strong winds.  Lightning struck a car near Osceola in Clarke County.  It struck the trunk of the car and set the trunk on fire.

Lightning in CLARKE, IOWA
From 27-APR-14 13:38:00 to 27-APR-14 13:38:00 (CST-6)
Location: OSCEOLA
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

A car was struck by lightning on U.S. 34 near Osceola.  The trunk caught fire.

Funnel Cloud in WAPELLO, IOWA
From 27-APR-14 14:05:00 to 27-APR-14 14:05:00 (CST-6)
Location: BIDWELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 27-APR-14 07:05:00 to 27-APR-14 07:05:00 (CST-6)
Location: EVANSDALE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 27-APR-14 07:01:00 to 27-APR-14 07:01:00 (CST-6)
Location: WASHBURN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in SAC, IOWA
From 27-APR-14 12:34:00 to 27-APR-14 12:34:00 (CST-6)
Location: SAC CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in CLARKE, IOWA
From 27-APR-14 12:42:00 to 27-APR-14 12:42:00 (CST-6)
Location: OSCEOLA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CALHOUN, IOWA
From 27-APR-14 12:49:00 to 27-APR-14 12:49:00 (CST-6)
Location: LOHRVILLE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Unknown

Heavy Rain in POLK, IOWA
From 27-APR-14 13:32:00 to 27-APR-14 13:32:00 (CST-6)
Location: CLOVER HILLS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Six to nine inches of water in the road.

Heavy Rain in POLK, IOWA
From 27-APR-14 13:35:00 to 27-APR-14 13:35:00 (CST-6)
Location: LOVINGTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DAVIS, IOWA
From 27-APR-14 14:00:00 to 27-APR-14 14:00:00 (CST-6)
Location: WEST GROVE
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Large trees were reported down by 70 MPH winds.

Thunderstorm Wind in APPANOOSE, IOWA
From 27-APR-14 13:35:00 to 27-APR-14 13:35:00 (CST-6)
Location: CINCINNATI
Magnitude: 75.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Roofs were blown off farm outbuildings and several windows blown out of cars.

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:08:00 to 27-APR-14 14:08:00 (CST-6)
Location: BLAKESBURG
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Reported by the Blakesburg fire department.

Thunderstorm Wind in DAVIS, IOWA
From 27-APR-14 14:16:00 to 27-APR-14 14:16:00 (CST-6)
Location: BELKNAP
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winds estimated at 60 MPH.

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:12:00 to 27-APR-14 14:12:00 (CST-6)
Location: OTTUMWA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winds estimated at 60 MPH.

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:20:00 to 27-APR-14 14:20:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:06:00 to 27-APR-14 14:06:00 (CST-6)
Location: BIDWELL
Magnitude: 75.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Major structural damage to at least one farmstead.  Roofs were blown off of outbuildings, damage to homestead roof and porch as well.  Many 12-18 inch diameter trees were snapped.

Thunderstorm Wind in MAHASKA, IOWA
From 27-APR-14 14:21:00 to 27-APR-14 14:21:00 (CST-6)
Location: OSKALOOSA
Magnitude: 75.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Roof taken off of the Oskaloosa Family Medical Center.

Hail in WAPELLO, IOWA
From 27-APR-14 14:15:00 to 27-APR-14 14:15:00 (CST-6)
Location: OTTUMWA
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in APPANOOSE, IOWA
From 27-APR-14 14:00:00 to 27-APR-14 14:00:00 (CST-6)
Location: SHARON
Magnitude: 75.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several outbuildings damaged or destroyed.  Carports were overturned with 12 to 15 inch diameter trees snapped off.  Power lines were downed with cattle trapped in a pole barn.

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:12:00 to 27-APR-14 14:12:00 (CST-6)
Location: OTTUMWA
Magnitude: 79.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm wind damage was reported in the 1000 block of west Mary St. in Ottumwa.  Two foot diameter trees blown over, flag poles were bent in half and a grain bin roof was removed and blown 200 yards.

Thunderstorm Wind in MAHASKA, IOWA
From 27-APR-14 14:20:00 to 27-APR-14 14:20:00 (CST-6)
Location: OSKALOOSA
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees up to 24 inch diameter downed.

Thunderstorm Wind in APPANOOSE, IOWA
From 27-APR-14 14:00:00 to 27-APR-14 14:00:00 (CST-6)
Location: UDELL
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A woman was injured by flying debris.

Thunderstorm Wind in POWESHIEK, IOWA
From 27-APR-14 14:37:00 to 27-APR-14 14:37:00 (CST-6)
Location: GRINNELL
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Trees down in the area caused by high thunderstorm winds.

Tornado in WAPELLO, IOWA
From 27-APR-14 14:20:00 to 27-APR-14 14:23:00 (CST-6)
Location: HIGHLAND CENTER
Tornado F-scale: EF1
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado formed initially as a broad circulation east of Highland Center.  First damage was to a farm site where a chicken barn was destroyed and two power poles were snapped.  As the tornado traveled quickly to the northeast and struck utility poles producing a considerable lean.  The tornado then continued into Keokuk county.

Thunderstorm Wind in POWESHIEK, IOWA
From 27-APR-14 14:38:00 to 27-APR-14 14:38:00 (CST-6)
Location: GRINNELL
Magnitude: 50.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Social Media

Damage to outbuildings and a trailer was caused by high thunderstorm winds.

Thunderstorm Wind in MAHASKA, IOWA
From 27-APR-14 14:13:00 to 27-APR-14 14:13:00 (CST-6)
Location: BEACON
Magnitude: 52.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Portion of the roof from a machine shed was torn off. Power poles were snapped off near the base and large trees were downed.

Thunderstorm Wind in MONROE, IOWA
From 27-APR-14 14:00:00 to 27-APR-14 14:00:00 (CST-6)
Location: LOVILIA
Magnitude: 70.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Roofs torn off of houses and trees snapped off.

Thunderstorm Wind in WAPELLO, IOWA
From 27-APR-14 14:18:00 to 27-APR-14 14:18:00 (CST-6)
Location: DAHLONEGA
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Six to 10 inch tree limb damage and an empty enclosed trailer blown over.