GOES-R IFR Probability Field and GOES-13 Brightness Temperature Difference (10.7µm – 3.9µm) at 1145 UTC on 3 November 2015. Surface-based observations of ceilings and visibilities are plotted (Click to enlarge)

Fog was widespread over the central United States on the morning of 3 November, and Dense Fog Advisories were commonplace. The toggle above compares the Brightness Temperature Difference field (10.7 µm – 3.9 µm) with the GOES-R IFR Probability field at 1145 UTC on 3 November.  (This toggle is much faster)  IFR Probabilities use near-surface information in the Rapid Refresh Model to screen out regions where Brightness Temperature Difference signals are showing elevated stratus rather than fog  (For example, the region around Columbus MS).  IFR Probabilities are also low in regions with a modest brightness temperature difference return (most of eastern Nebraska, west Texas, southern Indiana along the Ohio River);  these regions do not include stations observing IFR Conditions.