Panoramic view of Puerto Vallarta, Mexico. Credit: Piero Damiani/Getty Images Major airlines canceled flights and issued travel alerts on Monday for areas across Mexico following a surge of violence in the country after a powerful cartel leader was killed over the weekend. Following the unrest, the U.S. Embassy and Consulates in Mexico issued a security alert on Sunday for several states, including Jalisco, which includes the popular destinations of Puerto Vallarta and Guadalajara. "Due to ongoing security operations and related road blockages and criminal activity, U.S. citizens in the named locations should shelter in place until further notice," the embassy warned, adding travelers should avoid areas with law enforcement activity, be aware of their surroundings, avoid crowds, and minimize unnecessary movements.…