Unless this is occuring all the time, it sounds like the weather transition bug. Not everyone has seen it but it occurs when the weather is about to change. It kinda looks like the clouds are abstract art, made up of 'triangles' of varying sizes and they occasionally flash or flicker.
If this is the case a short spell at TC while submerged will usually clear it.
It's not related to GWX per se but rather the edited/improved scene.dats that have been developed, which have been used in many major mods.
A screenie will help though.
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