On the afternoon of March 21st, two areas of what could be low clouds and/or sea fog were moving north with the southerly low-level winds over the cool NW Gulf of Mexico shelf waters, toward the upper southeast Texas and southwest Louisiana coastlines. These clouds were moving onshore between the observing sites of GLS (just west of the image) and the Sabine Oil platform (VBS) which is shown in green with temps/dew points of 70/66 and 72/68.
The high resolution 1930Z MODIS image revealed that convective cloud elements were present, as opposed to the more laminar look of stratus and/or sea fog that the lower resolution GOES products at 1915Z and 1945Z depicted. The high resolution image at 1930Z aided the forecaster in identifying a cumulus cloud field as opposed to stratus and/or sea fog. This was helpful as sea fog disrupts marine travel in Galveston bay and is a big forecast problem. The 1930Z image also helped identify the cloud area off of the Southeast Texas coast (south/southeast of Rollover Pass), as it did not show up well in the lower resolution 1915Z GOES image.