First spotted by amateurs in Japan around December 9th, Saturn's new storm spans more than 100° of longitude as of January 5th, in the North Tropical Zone (roughly 34° north). This disturbance is not the same one noted by amateurs earlier this year, which appeared at a dynamic southern latitude band nicknamed "Storm Alley."
NASA / JPL / Space Science Inst.Veteran planet-watcher Thomas Dobbins notes the last time such a large storm appeared on Saturn was 1994, but that one had much lower contrast with its surroundings than the current event. This disturbance is easily the brightest feature on the globe — it even rivals the brightness of the planet's ring system. NASA's Cassini spacecraft has a "ringside" seat for the roiling clouds, as seen in the shot at right, which was taken on December 24th and transmitted to Earth on the 27th. Check the mission's website for other high-resolution images of the planet.