The significant contribution of the present NOAA profiler network (NPN) to operation forecast skill has been clearly demonstrated in recent profiler denial observing system experiments (OSEs) conducted at the Forecast Systems Laboratory (FSL). It has been hypothesized that expanding the profiler network to cover the entire continental United States or even a wider area of North America would lead to a further significant improvement in forecast skill. Because expansion of the profiler network would require a significant financial outlay, it is prudent to conduct an observing system simulation experiment (OSSE) to estimate the potential forecast impact from expanding the profiler network. Building upon the work already completed for the regional lidar OSSE, a profiler OSSE is being conducted by FSL. This OSSE will yield a quantitative assessment of the potential forecast improvement from expansion of the NPN. This estimate would be of sufficient quality to provide input to a cost-benefit analysis of the merits of an expanded profiler network. The design of the profiler OSSE closely follows that of the regional lidar OSSE recently conducted at FSL, utilizing a 10-km regional nature run (RNR) produced with MM5 and conventional observation simulators developed at FSL. Simulated wind profiler observations, which mimic the present NPN configuration, will be complemented by simulated profiler observations from various expanded network scenarios. In particular, a “full CONUS” scenario of approximately 120 profilers is being simulated and “full continent” scenarios including profilers in Canada and Mexico are being considered. The observations are being assimilated into the Rapid Update Cycle (RUC) model/assimilation system. In addition to the expanded profiler domain experiments, a simulated profiler data denial experiment is being completed, and the results compared with the recently completed real profiler data denial experiments. This calibration exercise is a crucial step in confirming the validity of the simulated data system and establishing the credibility of the OSSE results. Boundary conditions are supplied from the global lidar OSSE experiment in which only conventional observations are assimilated. Because the expanded profiler network will reside entirely within the RUC domain, forecast impacts from the assimilation of the additional profiler observations on the global domain (neglected in this OSSE) should be minimal. Research results to date will be presented at the conference.