IEM rainfall is a high resolution depiction of rainfall estimates over the state of Iowa. These estimates are provided freely via the Internet with no warranty or claim of accuracy. Currently, there are a number of ways you can view/download this dataset.
Please note that there is a current bug with how the one hour precipitation is generated by the MRMS project. The bug prevents the proper delination between zero and missing precipitation. The IEM has long whined to the MRMS project about fixing this bug.