This study employs the GEOS-5 atmospheric general circulation model (AGCM) run at high resolution (1/4°) and forced with observed SST to examine the factors that lead to the central US flooding and extreme weather activity during the spring of 2011. The simulations, consisting of 10-member ensembles of three-month long simulations (initialized March 1), reproduce the main features of the observed changes including the below–normal temperature in the north, above-normal temperature in the gulf region, and enhanced precipitation in the central US. Additional high-resolution runs are being used to investigate the ability of GEOS-5 to simulate a variety of severe weather events over the US with a focus on the meso-scale features that contribute to tornadic activity.