Fog engulfed northeastern Colorado this morning. Thick fog persisted over several hours, along the northern, I-25 corridor and eastern Colorado plains. Real-time surface observations below, can point out the foggy areas, indicated by the horizontal, parallel, pink lines. Surface observations (05-14Z, 26 March 2018) are over Colorado, and the neighboring states.
In complement to surface observations, fog can be seen via satellite imagery. The following two satellite images show the Near-Constant Contrast (NCC) product, that illuminates atmospheric features (e.g. liquid and ice clouds) and senses emitted lights (i.e. city lights) during the nighttime, in comparison to the GOES-16 satellite fog product. For both images, the domain of interest is highlighted by the large box over northeastern Colorado and the time is approximately 0915Z (0315 local time), 26 March 2018.
The NCC, below, shows cloud cover over the majority of the state along with emitted city lights. An interesting feature to point out in the imagery, is the difference in cloud texture. The clouds within the large box are grey and smooth, in comparison to the clouds southeast of the box, that are rather apparent and reflective . If one had not looked at surface observations, how could one tell where the fog is located? That is, how could one tell where the liquid water clouds (i.e. fog) are located, in comparison to the ice clouds? The GOES-16 Fog product assists in addressing the question.
The GOES-16 Fog Product (below) is a difference channel product between the 3.9um and 11.3um spectral channels, where negative values (white colors), indicate liquid water clouds and positive values (magenta) indicate ice clouds. The GOES-16 Fog Product can differentiate between the two types of clouds easily, where liquid water clouds are predominately located within the domain of interest. Additionally since fog was reported by surface observations in this domain, we can be confident that low-lying liquid water clouds were present this morning, in northeastern Colorado.
GOES-16 Fog Product (3.9um – 11.3um)