Tropical Depression 18W was a weak, short-lived tropical cyclone that brought heavy rains to parts of the Mariana Islands ahead of the more intense Typhoon Melor. Forming from an area of low pressure on September 26, 18W was first monitored by the Japan Meteorological Agency (JMA) as a tropical depression. Tracking generally towards the west, deep convection gradually developed around the system and the Joint Typhoon Warning Center (JTWC) issued their first advisory on the depression early on September 28. Although the depression initially struggled to maintain deep convection, it eventually became better organized and was upgraded to a tropical storm on September 29 by the JTWC. Several hours after reaching this intensity, the system began to rapidly dissipate as its inflow and outflow we