[citation needed] On October 8, 2013 the Japan Meteorological Agency (JMA) started to monitor a tropical depression, that developed within an area of low to moderate vertical windshear, about 1,150 km (715 mi) to the east of Manila on the Philippine island of Luzon.

[1][2] The system was subsequently named Santi by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) as it moved along the southern edge of a subtropical ridge of high pressure.

[3] During the next day after central convection over the systems low level circulation centre had increased both the JMA and the JTWC reported that the depression had developed into a tropical storm, with the latter naming it as Nari.

[1][5] Nari ensued a period of rapid intensification in the Philippine Sea, with the Japan Meteorological Agency and PAGASA upgrading the system into a typhoon.

[12] During October 11, the areas under signal 3 were expanded to include Benguet, Ifugao, Ilocos Sur, Isabela, La Union, Pangasinan, Polillo Island, Quirino, Nueva Ecija and Tarlac.

[18] On October 16, poor weather from the remnants of Typhoon Nari has been cited as a probable cause for the crash of Lao Airlines Flight 301, on approach to Pakse International Airport with the loss of all 49 passengers and crew.