Tropical Storm 06W – Tropical Cyclone Advisory #4: 1500 UTC 12 July 2025

…Tropical Storm 06W beginning to move northward and passing south of the Ogasawara Islands…

Current storm information:

• Position: 25.0°N 141.7°E

• Movement: NNE at 5 knots (10 km/h)

• Intensity: 35 knots (65 km/h)

• Central pressure: 998 hPa

Trend:

• Some strengthening is forecast during the next 24 hours.

Watches and warnings:

• There are no land-based watches or warnings in effect.

Hazards affecting land:

• Interests along the eastern coast of Honshu and in the Aleutian Islands should monitor the progress of this system.

Discussion:

Tropical Storm 06W remains a sheared system, but it is a bit better organized tonight. The circulation center is no longer exposed and is tucked under the northern edge of the convection. The convection is ragged and consists of fragmented bands mainly to the south and southwest of the center. The storm’s asymmetric appearance is the result of a frontal trough to the north impinging upon its circulation. The intensity remains 35 kts, based on consensus T2.5 Dvorak fixes, though some of the automated estimates are slightly higher.

TS 06W is finally on the move as it gets swept up in strong southerly flow between the trough to the north and strong subtropical ridging to the northeast, and the storm should accelerate quickly northward during the next couple of days. As it does, it should move under the upper-level trough, which should lessen the shear and allow for some strengthening. 06W will likely reach peak intensity on Monday as it approaches the eastern coast of Honshu. By later on Monday, increasing shear, cooling SSTs, and interaction with the frontal system should cause 06W to rapidly lose its tropical characteristics and become a post-tropical cyclone. The post-tropical cyclone should turn sharply east-northeastward as it rounds the subtropical ridge, and it will likely exit the basin by Thursday as it approaches the Aleutian Islands.

Although the forecast track brings 06W fairly close to Honshu, as it will be losing tropical characteristics, most of the wind and rain associated with it will likely remain offshore, though this could change if 06W tracks a bit further west than currently forecast. As a result, interests there should monitor its progress.

Forecast positions and maximum winds

• 00 hrs: 25.0°N 141.7°E – 35 kts

• 12 hrs: 26.5°N 142.3°E – 40 kts

• 24 hrs: 29.6°N 142.4°E – 50 kts

• 48 hrs: 37.9°N 142.1°E – 50 kts Post-tropical/extratropical

• 72 hrs: 46.8°N 150.6°E – 35 kts Post-tropical/extratropical

• 96 hrs: 48.0°N 163.8°E – 35 kts Post-tropical/extratropical

• 120 hrs: 50.0°N 179.2°W – 40 kts Post-tropical/extratropical