Complex sentence: After crossing the Baja, Kirsten veered to the northwest, making landfall about halfway between Los Mochis and Ciudad Obregon, Mexico, and weakening to a remnant low after crossing the Sierra Madre mountains.
Split into simpler sentences: After crossing the Baja, Kirsten veered to the northwest, making landfall about halfway between Los Mochis and Ciudad Obregon, Mexico. After making landfall, Kirsten weakened to a remnant low after crossing the Sierra Madre mountains.