western pacific Tropical Storm Kammuri

[Somerset Squall]

A new tropical storm has formed well southeast of Iwo To, Japan. The storm is named Kammuri, with winds of 35kts according to JMA. Kammuri is expected to strengthen as shear is relatively low and waters warm. Kammuri is expected to move slowly northwestward towards Iwo To, in a weak steering environment. Beyond this time, there is some uncertainty, but current thinking is that Kammuri will recurve to the northeast south of mainland Japan, as a trough creates a weakeness in the subtropical steering ridge to the north. The timing of this turn is uncertain. As poleward outflow continues to improve, Kammuri should strengthen into a typhoon, before weakening occurs by day 4/5 as sheat increases and waters cool along track.

[Somerset Squall]

Kammuri is a large storm, with broken convection over the centre, but strong and impressive peripheral banding features. Winds are up to 40kts according to JMA. Futher strengthening is expected as shear is low and outflow good, but the large size of Kammuri argues against rapid intensification.

[Somerset Squall]

Kammuri has continued to intensify, with winds now at 55kts. Further strengthening is expected in the low shear/excellent outflow environment, and Kammuri should become a typhoon soon.

[Somerset Squall]

Kammuri has not become a typhoon due to a premature rise in shear. The shear capped Kammuri's maximum winds at 55kts, and the storm has now started to weaken. Most of the increasingly shallow convection associated with Kammuri is displaced northeast of the LLCC. With waters cooling along track south and east of Japan, Kammuri will soon begin extratropical transition.

[Somerset Squall]

The last advisory on Kammuri has been issued by JTWC as Kammuri has almost completed extratropical transition. This will be complete within 12 hours.