Ceilings and visibilities over South Carolina decreased during the day on 24 September 2015. The animation of hourly IFR Probability fields, above, shows an increase in Probability over South Carolina as the visibilities decreased. IFR Probability fields can alert a forecaster to the possibility of IFR conditions at any time of the day. Visible imagery for the same period, below, shows the multiple cloud layers streaming inland. The accuracy of the IFR Probability field in highlighting the region with near-IFR and IFR Probability is testimony to the accuracy of the Rapid Refresh model data that are used.