TEMPEST-D is a technology demonstration mission to enable millimeter wave radiometer technologies on a low-cost, short development schedule. The mission, led by Principal Investigator (PI), Prof. Steven C. Reising of Colorado State University (CSU) in partnership with JPL and Blue Canyon Technologies (BCT), reduces the risk, cost, and development duration for a future TEMPEST mission, which would provide the first ever temporal observations of cloud and precipitation processes on a global scale. TEMPEST-D is sponsored by the NASA's Earth System Science Pathfinder (ESSP) program and managed by the Earth Science Technology Office (ESTO). For TEMPEST-D, JPL developed a mm-wave radiometer payload that operates at five channels from 89 to 182 GHz and fits in a 4U volume within the 6U CubeSat.