pre-storm gloomy gray, purple, dark blue sky, covered with solid fluffy clouds.

agents alarm anxiety apprehension atmospheric bad black blue cloud clouded clouds covered cumuli cumulus dark deteriorate downy dramatic drawing eloquent fleecy fluffy forcible forecast forerunners form foul gloomy gray inclement meteorological meteorology nasty overcast phenomena prepare prestorm purple rain rainclouds shape sky solid storm strata thicken thickening thicker thunderstorm ugly uneasiness violaceous violet weather white