Weather affects military operations, and simulated military operations should be similarly affected if these simulations are to deliver value to training, mission rehearsal, acquisition and other simulation-enabled communities across the DoD. Immersive simulations must derive human visibility with explicit or implicit assumptions about temperature, dew point and aerosol content in the space between player and target. Simulations of land, sea and air vehicles must make some set of assumptions about trafficability, wave heights, and turbulence or wind shear, even if the assumption is that these conditions are benign. The space environment, ionosphere and sensible weather (e.g., rain showers or thunderstorms) dramatically impact real command, control, communications, and computers (C4), and simulated C4 systems should be similarly, realistically affected. Achieving this level of fidelity in constructive simulations requires an authoritative representation of the natural environment driving a set of validated, calibrated behaviors within these simulations. In this study, the Army OneSAF simulation system is used to revisit combat operations in the early days of Operation Iraqi Freedom during a severe and extended dust storm event (March 25-27, 2003). With the passage of a long, dry cold front through the region, sand and dust obscured visibility in the lower atmosphere in a wide swath down to the Arabian Gulf. This event limited ground, air and maritime operations and drove commanders in the field to operational and tactical improvisation. Using an authoritative representation of weather in southern Iraq, OneSAF simulation outcomes are examined and these results compared to known combat outcomes and mission limitations. These results provide insight and a starting point for improving model behaviors in OneSAF and other simulation systems.