early on september 8, a cluster of thunderstorms came together as a low pressure area with imporoving outflow and a developing low-level circulation center (llcc). later that day, the jma upgraded the low pressure area to a tropical depression north-northeast of the northern mariana islands. over the next two days, the system gradually drifted west and intensified slightly, prompting the jtwc to issue a tropical cyclone formation alert (tcfa) on it. convection gradually consolidated the llcc and the jtwc initiated advisories on the system on september 11, designating it with "18w". the next day, the depression drifted into the philippine area of responsibility (par) and the pagasa initiated advisories on the depression, naming it "onyok". however, just as similar to kulap, onyok also exited the par in 6 hours from entering the region. in an advisory, the jtwc reported that there were at-least two more vortices associated with the system, that caused an abrupt, erratic movement. however, being in an area of warm sea surface temperatures and low vertical wind shear, the depression continued to strengthen and on september 13, the jma upgraded the depression to a tropical storm and named it "roke". on september 17, roke developed a small, deep convective eye promoting the jma to upgrade roke to a severe tropical storm with winds of over . between september 19 and 20, roke underwent "explosive intensification", a more extreme case of rapid deepening that involves a tropical cyclone deepening at a rate of at least 2.5 mbar per hour for a minimum of 12 hours. also, they added that roke developed a eye and a good poleward outflow channel. on september 21, typhoon roke made landfall over hamamatsu, japan at about 5:00 utc (14:00 jst). soon roke started weakening as cloud tops started getting warmed up and eye diameter started to decrease. however, the system still maintained a near radial outflow and the convective structure continued to remain organized that kept roke from dissipating rapidly. although roke entered a de-intensification phase, it still had plenty of strength that posed a great threat to regions of japan. being about southwest of yokosuka, kanagawa, the typhoon accelerated north-northwestward at about with winds of over (1-min sustained) being a category 3 typhoon on the sshs. being embedded in the baroclinic zone, roke started its extratropical transition. also, land interaction severely weakened the storm to a minimal category 1 typhoon with winds of under (1-min sustained). only six hours later, the storm further weakened and accelerated northeastward at about with rapidly dissipating deep convection completely sheared to the northeast of the llcc. as a result, the jtwc ceased advisories on the storm, as it became fully extratropical.