Over the last several years considerable effort has been made toward improving tropical cyclone (TC) track and intensity forecasts. This is due, in part, to improved physics and dynamics in NWP models and, in part to improved data assimilation (DA) as well as an increased number of observations. Despite the availability of satellite based radiance observations there utilization in mesoscale models has been limited. In this talk the impact of assimilating radiance observations with a serial ensemble Kalman filter (EnKF) will be discussed in the context of TC forecasts from the Couple Ocean/Atmosphere Mesoscale Prediction System–TC (COAMP-TC). In particular, experiments in which AMSU-A microwave brightness temperature are assimilated into COAMPS-TC with the DA Research Testbed (DART) will be compared to experiments in which radiances are withheld. The impact of assimilation on TC track and intensity forecasts will be presented for the Atlantic, Eastern Pacific, and Western Pacific for the 2010 and 2011 seasons. The impact of vertical localization on radiance assimilation will also be discussed.