Tropical Depression (92W/Huaning) – Tropical Cyclone Advisory #1: 0000 UTC 18 August 2025

Tropical depression likely to bring very heavy rainfall to Okinawa by midweek.

Author

Will Weaver
August 17, 2025

…Tropical depression likely to bring very heavy rainfall to Okinawa by midweek…

Himawari-9 visible satellite image (Weathernerds)

Current storm information:

  • Position: 22.2°N 126.4°E

  • Movement: NNE at 5 knots (10 km/h)

  • Intensity: 30 knots (55 km/h)

  • Central pressure: 1009 hPa

Trend:

  • Some slight strengthening is possible during the next 24 hours, and the depression could become a tropical storm on Tuesday.

Watches and warnings:

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

Hazards affecting land:

  • The depression is likely to produce heavy rainfall and tropical storm force winds over portions of the Ryukyu Islands, including Okinawa, beginning on Tuesday and continuing into Wednesday. This rain could result in flash flooding. For additional information, refer to products from your local weather office.

Discussion:

Himawari-9 infrared satellite image (Weathernerds)

The minor tropical depression located northeast of Luzon (Invest 92W) has a strongly sheared appearance, but indications are that it is now producing winds near gale force. Scatterometer data indicates that the depression is producing a swath of 25 to 30 kt winds south and east of its center. The system itself is interacting with a TUTT cell located just to its northwest over the Yaeyama Islands, and is almost completely devoid of convection north and west of the center. The center is fairly well defined and is tucked just underneath the northwestern extent of the convective mass. The system is probably closer to being subtropical than fully tropical given its involvement with the TUTT cell, but either way, it has reached warning criteria with an intensity of 30 kts.

TD 92W is not forecast to become very strong. The environment is not favorable for strengthening given the close proximity of the TUTT cell, which is producing strong (25 to 30 kt) northerly shear over the system. As 92W rounds the eastern periphery of the cell, the shear should decrease slightly, and this will likely enable it to become a tropical storm. However, continued shear and a very dry air mass to the north will preclude any additional strengthening as 92W moves generally northward. By Thursday, steering currents are forecast to collapse as the TUTT cell dissipates and strong ridging builds in over the Sea of Japan, effectively blocking further progress. This will cause 92W to stall over marginally warm SSTs, and 92W will likely weaken back to a depression near Kyushu by the end of the forecast period.

Forecast positions and maximum winds

  • 00 hrs: 22.2°N 126.4°E – 30 kts

  • 12 hrs: 24.1°N 127.2°E – 30 kts

  • 24 hrs: 25.8°N 127.1°E – 35 kts 

  • 48 hrs: 29.0°N 126.8°E – 35 kts 

  • 72 hrs: 30.9°N 127.6°E – 35 kts

  • 96 hrs: 31.8°N 128.0°E – 35 kts 

  • 120 hrs: 32.7°N 128.2°E – 30 kts 

JMA forecast map