A strong upper level low pressure area moved into the central U.S.  Ahead of it, a surface low formed to the west of Iowa along an approaching cold front.  Southerly winds pushed moisture north with precipitable water values increasing to 1.25 to 1.5 inches, near the 99th percentile for the time of year.  Surface dewpoints surged into the mid 60s with elevated CAPE values of 1000 J/kg present.  Weak shear was in place with 20 to 30 kts of effective shear.  The freezing level was around 11,500 feet with CAPE in the -10 to -30 C layer of the atmosphere between 300 and 400 J/kg.  This was enough to produce some penny size hail in Cass County south of Atlantic.  Although there was about 1000 J/kg of downdraft CAPE present, it was not able to be realized as the low levels of the atmosphere had cooled before the storms moved into the area.  Gusty winds of 30 to 40 MPH occurred however.  Several locations reported 3 to 5 inches of rain from central into southeast Iowa.  The rain fell in a 24 hour period for the most part.  A few totals noted went from Friday evening into Sunday morning, however nearly all of the accumulating rainfall occurred Saturday into Saturday night.

Heavy Rain in JASPER, IOWA
From 13-OCT-12 06:00:00 to 14-OCT-12 06:00:00 (CST-6)
Location: NEWTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Near I-80 and Highway 14 interchange.  Storm total since Friday evening was 4.25 inches.

Hail in CASS, IOWA
From 13-OCT-12 20:44:00 to 13-OCT-12 20:44:00 (CST-6)
Location: ATLANTIC
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in JASPER, IOWA
From 13-OCT-12 06:01:00 to 14-OCT-12 06:01:00 (CST-6)
Location: PRAIRIE CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Twenty four hour rainfall from Neil Smith Wildlife Refuge.  Total was 3.13 inches.

Heavy Rain in JASPER, IOWA
From 13-OCT-12 06:02:00 to 14-OCT-12 06:02:00 (CST-6)
Location: NEWTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Twenty four hour total from APRS weather network.  Total was 3.42 inches.

Heavy Rain in DAVIS, IOWA
From 13-OCT-12 06:19:00 to 14-OCT-12 06:19:00 (CST-6)
Location: BLOOMFIELD
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Coop reported 3.40 inches of rain.  Was 48 hour total, but very little fell before Saturday morning.

Heavy Rain in CASS, IOWA
From 13-OCT-12 06:23:00 to 14-OCT-12 06:23:00 (CST-6)
Location: CUMBERLAND
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Twenty four hour total of 5.10 inches.

Heavy Rain in JASPER, IOWA
From 13-OCT-12 06:43:00 to 14-OCT-12 06:43:00 (CST-6)
Location: NEWTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Twenty four hour total of 3.06 inches.

Heavy Rain in MARION, IOWA
From 13-OCT-12 08:23:00 to 14-OCT-12 08:23:00 (CST-6)
Location: BUSSEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Twenty four hour total of 3.02 inches.

Heavy Rain in APPANOOSE, IOWA
From 13-OCT-12 08:31:00 to 14-OCT-12 08:31:00 (CST-6)
Location: CENTERVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Twenty four hour total of 3.29 inches.

Heavy Rain in WAPELLO, IOWA
From 13-OCT-12 10:37:00 to 14-OCT-12 10:37:00 (CST-6)
Location: RUTLEDGE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Total rainfall of 4.90 inches in 36 hours, most of which was in past 24 hours.