Hurricane Katia was a powerful tropical cyclone that had substantial impact across Europe as a post-tropical cyclone. The eleventh named storm, second hurricane, and second major hurricane of the active 2011 Atlantic hurricane season, Katia originated as a tropical depression from a tropical wave over the eastern Atlantic on August 29. It intensified into a tropical storm the following day and further developed into a hurricane by September 1, although unfavorable atmospheric conditions hindered strengthening thereafter. As the storm began to recurve over the western Atlantic, a more hospitable regime allowed Katia to become a major hurricane by September 5 and peak as a Category 4 hurricane with winds of 140 mph (230 km/h) that afternoon. Internal core processes, increased wind shear, an impinging cold front, and increasingly cool ocean temperatures all prompted the cyclone to weaken almost immediately after peak, and Katia ultimately transitioned into an extratropical cyclone on September 10. Category 4 hurricane: peak winds of 140 mph (120 knots), lowest pressure 942 mb. August 28 – September 12, 2011. Accumulated cyclone energy: 27.0. Wiki link Track: NOAA National Hurricane Center, HURDAT2 best track AL122011 (public domain).