October 2009 North American storm complex
The October 2009 North American storm complex was a powerful extratropical cyclone that was associated with the remnants of Typhoon Melor, which brought extreme amounts of rainfall to California. The system started out as a weak area of low pressure (an Aleutian Low), that formed in the northern Gulf of Alaska on October 7.
Source: Wikipedia — October 2009 North American storm complex (CC BY-SA 4.0)