|GOES-R IFR Probabilities (Upper Left), GOES-East Brightness Temperature Difference (10.7 µm – 3.9 µm) (Upper Right), GOES-R Cloud Thickness (Lower Left), GOES-East 6.5 µm imagery (Lower Right), from ~0000 UTC on 3 January 2013|
GOES-R IFR Probabilities captured the evolution of IFR (and Low IFR) conditions over and around the Florida peninsula from late on 2 January through morning on 3 January 2013. Advection fog over the chilly coastal waters of the eastern Gulf of Mexico stayed mainly offshore (although Sarasota at 00 UTC reports IFR conditions) and is captured well by the GOES-R product. This is a region underneath high cirrus and as such, the traditional brightness temperature product is blind to the existence of low clouds there.
Over the course of the night, fog and low stratus developed over land, and the GOES-R IFR probability product captured that evolution as well (below, hourly imagery). Again, there are regions where the brightness temperature difference product is not useable because of multiple cloud layers, and the Rapid Refresh Model output is controlling the IFR Probabilities — these are regions where the IFR probability field is very smooth and typically exhibits lower probability values even though IFR conditions may be observed (For example, at Gainesville and Jacksonville at 0600 UTC). By morning, visibilities were under 1/4 mile over much of the central Florida Peninsula (For example, Orlando).
|As above, but hourly imagery from 0000 UTC through 1400 UTC on 3 January 2013.|
The 3/4-full moon allows for plenty of illumination for the Day/Night band on VIIRS, which is flying on Suomi/NPP. The 0700 UTC imagery, below, demonstrates the difficulty of using the DNB at night to detect fog — city lights that shine through low clouds. Fog is detected in rural regions, but where city lights exist, the signal is difficult to extract.
|GOES-R IFR Probabilities (Upper Left), GOES-East Brightness Temperature Difference (10.7 µm – 3.9 µm) (Upper Right), GOES-R Cloud Thickness (Lower Left), Suomi/NPP VIIRS Day/Night Band 0.7 µm imagery (Lower Right), from ~0700 UTC on 3 January 2013|
The visible imagery at 1500 UTC, below, shows the horizontal extent of the stratus deck through central Florida. The region matches well with the IFR Probabilities because visible imagery during the day is used as a cloud-clearing mechanism in the GOES-R algorithms. Note also how the reflected 3.9 µm solar radiation during the day renders the brightness temperature difference product ineffectual.
|GOES-R IFR Probabilities (Upper Left), GOES-East Brightness Temperature Difference (10.7 µm – 3.9 µm) (Upper Right), GOES-R Cloud Thickness (Lower Left), GOES-East visible (0.63 µm) imagery (Lower Right), from ~1500 UTC on 3 January 2013|