Tropical Storm Sepat 2025

Live tracking map, satellite images and forecasts of Tropical Storm Sepat 2025 (台風2号) south of Japan. Current wind speed 65km/h. Max 75km/h.

Sepat is located 678 km south of Yokosuka, Japan, and has tracked northwestward at 22 km/h (12 knots) over the past 6 hours. Maximum significant wave height is 5.2 meters (17 feet).

Sepat is anticipated to continue tracking towards the northwest at a steadily decreasing speed as it approaches the subtropical ridge axis over the next 24 hours.

The system is expected to reach the ridge axis in 24 hours, and thereafter will accelerate northeastward along the northwestern side of the ridge through the remainder of the forecast period.

Sepat is expected to brush the eastern coast of the Boso Peninsula in 36 to 48 hours as it accelerates northeastward. Due to increasing convergence aloft as well as increasing shear, Sepat is forecast to weaken over the next 12 hours, then maintain that intensity as it approaches eastern Honshu.

The system crosses the 26°C isotherm in 36 hours as a weak tropical storm, just beginning the early phases of extratropical transition (ETT).

As the system reaches closest point of approach to Yokosuka, it will begin interacting with the divergent region ahead of a negatively tilted major shortwave trough approaching from the west.

The rapid increase in outflow aloft, coupled with some baroclinic forcing, will result in an increase in intensity as the system undergoes ETT to the northeast of Tokyo.

Sepat is forecast to complete ETT shortly after 2 days as it moves into phase with the major shortwave trough and begins to develop frontal characteristics.

Deterministic and ensemble track guidance is in good agreement, with minimal cross- or along-track spread over the next 2 days. Model spread increases after 2 days, during the ETT and recurve phase, up to 370 km by the end of the forecast.

The JTWC forecast remains consistent with the previous track and the ECMWF tracker, placed with high confidence. Intensity guidance is mixed, with both Decay-SHIPS models indicating intensification over the next 2 days, while the remainder of the guidance package shows weakening through 24, steady-state over the next 36 hours and reintensification after 36 hours as the system begins ETT.

The JTWC forecast closely tracks the HAFS-A member through the forecast period with medium confidence.