On August 14 at 06:00 UTC, the Joint Typhoon Warning Center (JTWC) began monitoring an area of convection approximately 435 nautical miles (805 km; 500 mi) southeast of Andersen Air Force Base, assessing its development potential in the next day as low.

[1] Convective bands began to form around the system, though they remained shallow; by 15:00 UTC, the JTWC upgraded its development potential in the next day to medium.

[2] Convection began to deepen and wrap into a consolidating low-level circulation, and at 22:30 UTC, the JTWC issued a Tropical Cyclone Formation Alert on the system.

[3] On August 15 at 06:00 UTC, the Japan Meteorological Agency (JMA) began monitoring a tropical depression in the Philippine Sea.

[9] Convective banding began to wrap into the still-exposed low-level circulation, and at 03:00 UTC, the JTWC also upgraded Soulik to a tropical storm.