Sarika was first noted by the United States-based Joint Typhoon Warning Center (JTWC) as a disorganized tropical disturbance on October 11, while it was about 1,050 km (650 mi) southeast of Manila.[1] The system quickly consolidated within a favorable environment of low wind shear and high sea surface temperatures of about 30 °C (86 °F), leading the JTWC to issue a Tropical Cyclone Formation Alert.[2] By 00:00 UTC on October 13, the system's low-level circulation center became increasingly symmetric as it tracked northwestwards and the Japan Meteorological Agency (JMA) upgraded the disturbance to a tropical depression.[3][4][nb 2] The JTWC followed suit six hours later.[5] Intensification slowed thereafter as an upper-level anticyclone suppressed outflow on the eastern side of the system.