Tracking westwards, it rapidly upgraded into a tropical storm, receiving the name Prapiroon due to favorable conditions in the Philippine Sea on the next day.

Shortly after reaching peak intensity, Prapiroon weakened into a tropical storm after passing closely between Japan and the Korean Peninsula.

On June 27 at 20:00 UTC, the Joint Typhoon Warning Center (JTWC) began monitoring a system in the Philippine Sea, giving it a low development potential.

[6] At 03:00 UTC the same day, the JTWC upgraded Prapiroon to a tropical storm as it was located approximately 440 nautical miles (815 km; 505 mi) south-southeast of Kadena Air Base.

[14][15] After peaking, Prapiroon began to weaken and turn to the northeast, with the JMA downgrading it to a severe tropical storm on July 3 at 06:00 UTC as conditions for development became unfavorable.

[16] The JTWC downgraded Prapiroon to a tropical storm at 15:00 UTC as its low-level circulation became exposed, with central convection becoming elongated.

[17] Prapiroon's western semicircle became completely devoid of deep convection,[18] and by July 4 at 00:00 UTC, the JMA further downgraded it to a tropical storm.