Tropical Depression 20W – Tropical Cyclone Advisory #3: 1200 UTC 29 August 2025

Poorly organized depression passing to the south of Hainan Island.

Author

Will Weaver
August 29, 2025

…Poorly organized depression passing to the south of Hainan Island…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 17.2°N 110.8°E

  • Movement: W at 12 knots (25 km/h)

  • Intensity: 30 knots (55 km/h)

  • Central pressure: 998 hPa

Trend:

  • Little change in strength is forecast during the next 24 hours, but TD 20W could briefly become a tropical storm later tonight or on Saturday.

Watches and warnings:

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

Hazards affecting land:

  • TD 20W is likely to bring areas of heavy rainfall to portions of Hainan Island and Vietnam through the weekend. Many areas that already saw heavy flooding rainfall from Typhoon Kajiki could see additional rain and flooding. For additional information, refer to products from your local weather office.

Discussion:

WSFM WMI 37GHz microwave satellite image, showing a rather broad circulation with fragmented banding

Tropical Depression 20W remains very poorly organized. Moderate easterly shear continues to displace most of its convection to the west of its center. TD 20W’s circulation also appears to have broadened over the past several hours, and the low cloud swirl has become somewhat more diffuse and difficult to discern on satellite imagery. The convection is also not well organized, consisting of fragmented bands trying to wrap loosely into the circulation center. HYSAT and Oceansat data suggest that 20W has not strengthened, and the intensity remains 30 kts.

There are no changes to the forecast as there is fairly strong agreement among the model guidance that 20W will continue on a west-northwestward track up until landfall in Vietnam on Saturday evening. The environment is expected to remain quite hostile and little change in strength is expected before then, although it is possible that 20W could briefly become a tropical storm just before landfall. After landfall, the circulation should rapidly decay and open up into a trough by Sunday.

Forecast positions and maximum winds

  • 00 hrs: 17.2°N 110.8°E – 30 kts 

  • 12 hrs: 17.7°N 108.5°E – 35 kts 

  • 24 hrs: 17.9°N 105.7°E – 25 kts inland

  • 48 hrs: 17.5°N 100.0°E – 20 kts inland

  • 72 hrs: Dissipated

JTWC forecast map

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