Here is the MODIS Fog (spectral diff) from early May 2, 2009. Below is the feedback from Gordon Strassberg (forecaster at MIA) on its application.
You can clearly see the fog indications (yellow areas) across much of interior South Florida. Unfortunately, the most frequent areas we get fog are these interior areas where the yellow is, and we have very little population since it’s mostly Everglades. However, that night we did observe pretty heavy fog on Alligator Alley just west of Snake Road on a traffic cam, which would be right in the middle of the large yellow area in western Broward County. There are, though, several areas where fog was not indicated by MODIS, that we received reports.
Our report of heaviest fog actually came from interior Palm Beach County, east of the town of Belle Glade on SR 880/US441/US 90 near Twenty-mile bend, if you can locate that. MODIS shows little to no fog there. This is sometimes the case, where MODIS indicates likely fog but calls right to that spot are clear–sometimes, when the MODIS indicates fog, it’s usually a good indication that fog is occurring, but it may not have the correct locations all of the time. But it is a good “heads up” for us to make some calls and find out how bad it may or may not be, or to issue a NOWcast to alert the public. Also the time the images come in is usually a little too early to capture the fog. For example, this image before 0700 UTC, 3AM LT, would on a normal night have been too early to capture the fog as it is usually first developing around then–however that night the fog happened to develop a little earlier than usual.