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We report on the long-term evolution of Saturn’s sixth Great White Spot (GWS) event that initiated at northern mid-latitudes of the planet on December 5th, 2010 (Fletcher, L. et al. [2011]. Science 332, 1413–1417; Sanchez-Lavega, A. et al. [2011]. Nature 475, 71–74; Fischer, G. et al. [2011]. Nature 475, 75–77). We find from ground-based observations that the GWS formed a planetary-scale disturbance that encircled the planet in 50 days, covering the latitude band between 24.6 and 44.8N (planetographic) or about 22,000 km in meridional extent and 280,000 km in full zonal circumference length. The head of the GWS was located at an averaged latitude of 40.8 ± 1N in the peak of a westward jet and showed a mean linear drift in System III longitude of 2.793 deg/day, equivalent to a mean zonal velocity of u = � 27.9 m s � 1 , with maximum speed fluctuations around this mean of � 5.3 to +2.7 m s � 1 . The differ