Hundred-year storms? That’s how long they last on Saturn.
Radio image of Saturn taken with the VLA in May 2015, with the brighter radio emissions from Saturn and its rings subtracted to enhance the contrast in the fainter radio emissions between the various latitudinal bands in the atmosphere. Since ammonia blocks radio waves, the bright features indicate areas where ammonia is depleted and the VLA could see deeper in the atmosphere. The broad bright band at northern latitudes is the aftermath of the 2010 storm on Saturn, which apparently depleted ammonia gas just below the ammonia-ice cloud, which is what we see with the naked eye. R. J. Sault and I. de Pater
A new study conducted by astronomers from the University of California, Berkeley, and the University of Michigan, Ann Arbor, shows that Saturn has long-lasting megastorms with impacts deep in the atmosphere that persist for centuries.