Thunderstorms from the previous night formed a mesoscale convective vorticity center (MCV) to the southwest of Iowa during the night of the 14th.  The MCV moved northeast during the day on the 15th.  Heating was somewhat limited due to residual clouds from the previous night, however it warmed enough to destabilize the atmosphere by mid afternoon.  CAPE was somewhat limited, around 1000 J/kg, with a lifted index in the zero to -3 range.  The shear was stronger than the previous night with 40 to 45 kts available.  The freezing level remained high, just above 14,000 feet.  The lower levels of the atmosphere were relatively dry, leading to a downdraft CAPE of 900 to 1300 J/kg.  That also lead to an LCL around 2000 meters.  In spite of the dry low levels, precipitable water values were in the 1.5 to 1.7 inch range.  Thunderstorms formed over northern Missouri and southern Iowa during the afternoon and lifted north.  For the most part they produced heavy rainfall, resulting in some street flooding in the Des Moines metro area, and also in Sac City in Sac County where 5.5 inches of rain fell during the day.  One storm produced high winds and caused tree damage in Pocahontas County.  There were also spotty reports of wind damage in Calhoun County.  One farm in the Jolley area sustained tree damage and some damage to outbuildings.

Heavy Rain in SAC, IOWA
From 15-JUN-12 15:12:00 to 15-JUN-12 15:12:00 (CST-6)
Location: SAC CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Street flooding was caused by a 20 minute period of heavy rain.

Heavy Rain in SAC, IOWA
From 15-JUN-12 06:00:00 to 15-JUN-12 15:32:00 (CST-6)
Location: SAC CITY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 5.5 inches of rain so far today.

Thunderstorm Wind in CALHOUN, IOWA
From 15-JUN-12 15:03:00 to 15-JUN-12 15:03:00 (CST-6)
Location: KNOKE
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Several six to eight inch tree limbs were blown down.  The top of a large tree was sheared off.  Pea size hail was also observed.

Thunderstorm Wind in CALHOUN, IOWA
From 15-JUN-12 15:31:00 to 15-JUN-12 15:31:00 (CST-6)
Location: JOLLEY
Magnitude: 57.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Public

Several large trees were blown down across town.  One tree fell on top of power lines, knocking them to the ground.

Thunderstorm Wind in POCAHONTAS, IOWA
From 15-JUN-12 15:44:00 to 15-JUN-12 15:44:00 (CST-6)
Location: VARINA
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

Several six inch limbs were blown down across the yard.  Pea size hail also observed.

Thunderstorm Wind in CALHOUN, IOWA
From 15-JUN-12 15:05:00 to 15-JUN-12 15:05:00 (CST-6)
Location: JOLLEY
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Damage reported to trees and outbuildings.

Heavy Rain in POLK, IOWA
From 15-JUN-12 15:12:00 to 15-JUN-12 15:12:00 (CST-6)
Location: FT DES MOINES
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy rainfall caused local low land flooding in the SE 14th and East McKinley street areas with water up to the fenders of cars.

Thunderstorm Wind in POCAHONTAS, IOWA
From 15-JUN-12 15:40:00 to 15-JUN-12 15:40:00 (CST-6)
Location: FONDA
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Tree branches were blown down by winds and heavy rainfall.

Heavy Rain in POCAHONTAS, IOWA
From 15-JUN-12 16:07:00 to 15-JUN-12 16:52:00 (CST-6)
Location: POCAHONTAS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Heavy rainfall with 1.85 inches falling in 45 minutes.