Pulasan developed over the Philippine Sea as a tropical depression on September 15 and strengthened into the fourteenth named storm of the annual typhoon season the following day.

After gaining organization, the system rapidly developed and reached its peak intensity with winds of 85 km/h (50 mph) and a central pressure of 992 hPa (29.29 inHg).

By September 21, Pulasan had transitioned into an extratropical low as it moved east-northeastward and became embedded within the polar front jet to the north, passing over southern South Korea.

Tropical Storm Pulasan emerged from an area of atmospheric convection 196 km (122 mi) west-southwest of Andersen Air Force Base, Guam on September 14.

[1] Satellite imagery indicated a broad, elongated area of circulation obscured by flaring and disorganized deep convection, with the disturbance situated in a favorable environment for development.

[2] The United States Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert, noting that the system was disorganized, deep, fragmented, and had flaring convection obscuring the low-level circulation.

[4] Pulasan was characterized by a large cyclonic circulation exceeding 1,111 kilometres (690 mi) and extensive gale-force winds, leading the JTWC to classify it as a monsoon depression at 06:00 UTC on September 16,[5] before later upgrading it to a tropical storm and designating it as 15W.

[9] The JMA reported that Pulasan reached its peak intensity at 00:00 UTC, with 10-minute sustained winds of 85 km/h (50 mph) and a central pressure of 992 hPa (29.29 inHg).

[10] Pulasan's low-level circulation has remained broad and somewhat exposed,[11] as dry air continues to encircle its southern side while the system moves northwestward along the southwestern edge of a mid-level subtropical high.

[16][17] As the storm moved overland, it maintained a well-defined circulation center;[18] however, the system gradually turned northeastward under the influence of mid-latitude prevailing westerlies.

[20] Meanwhile, satellite imagery and surface reports from Jeju Island indicated that it was in the earliest phase of extratropical transition, with vigorous deep convection occurring over the southern semicircle.

[21] By 06:00 UTC on September 21, the JMA reported that Pulasan had transitioned into an extratropical low as it moved east-northeastward and became embedded within the polar front jet to the north, passing over southern South Korea.