Typhoon Wipha (09W) – Tropical Cyclone Advisory #9: 0000 UTC 20 July 2025

Wipha becomes a typhoon as it passes just to the south of Hong Kong

Author

Will Weaver
July 19, 2025

…Wipha becomes a typhoon as it passes just to the south of Hong Kong…

Himawari-9 visible satellite image (Weathernerds)

Current storm information:

  • Position: 21.6°N 114.6°E

  • Movement: W at 11 knots (20 km/h)

  • Intensity: 65 knots (120 km/h) - Category 1

  • Central pressure: 970 hPa

Trend:

  • Some additional strengthening is possible during the next 12 hours. A slow weakening trend is forecast to begin tonight.

Watches and warnings:

  • No. 10 Hurricane Signal: Hong Kong. Typhoon force winds are expected during the next 12 to 18 hours. Waglan Island recently reported a sustained wind of 68 kts, while Tate’s Cairn reported a sustained wind of 68 kts and a gust to 90 kts.

  • No. 8 Storm Signal: Macau. Tropical storm force winds are expected during the next 12 to 24 hours, and Macau may be upgraded to the No. 10 Hurricane Signal later today.

Hazards affecting land:

  • Wipha is expected to produce strong tropical storm or typhoon conditions - potentially destructive winds, heavy surf, and heavy rain - across much of southern China during the next few days, including in Hong Kong and Macau and on Hainan Island. Winds will be stronger at higher elevations, such as upper floors of high-rise buildings, and heavy rainfall could result in flash flooding. For additional information, refer to products from your local weather office.

  • Wipha is likely to produce tropical storm conditions in northern Vietnam, including in the Hanoi metropolitan area, beginning on Tuesday. Heavy rainfall associated with Wipha and its remnants will spread over northern Laos and northern Thailand by Wednesday.

Discussion:

Himawari-9 visible satellite image (Weathernerds)

Although Wipha’s satellite presentation has not changed a whole lot during the past 12 hours, its internal structure has improved quite a bit. Radar data from Hong Kong indicates that Wipha’s inner core structure has become better defined with a mostly complete eyewall in place surrounding an irregularly shaped eye. This eye feature was apparent on satellite imagery an hour or so ago before being obscured by a large burst of convection southwest of the center. The northern eyewall is currently located directly over Hong Kong, which has seen sustained winds of typhoon force during the past few hours. Given that typhoon force winds are actually occurring in Hong Kong, and most of the satellite-based estimates are close to 65 kts (Dvorak T4.0), the intensity is increased to 65 kts. It is a mystery to me why JMA has this as a 55 kt tropical storm.

Composite radar image (CyclonicWx). Note the eye just south of Hong Kong.

Wipha has about 12 hours left over water before the center crosses the coast of southern China west of Macau. Some additional strengthening is possible before then. The center of Wipha is forecast to more or less skirt the coast and pass over the Leizhou Peninsula late tonight and early on Monday. Although land interaction will cause some weakening, Wipha could strengthen somewhat as it passes over the Gulf of Tonkin Monday into Tuesday, and Wipha could be near typhoon intensity again by the time it makes landfall in northern Vietnam on Tuesday evening. Wipha should quickly decay as it pushes inland and by Wednesday, it should be well into the process of decaying into a broad area of low pressure over northern Laos.

Forecast positions and maximum winds

  • 00 hrs: 21.6°N 114.6°E – 65 kts 

  • 12 hrs: 21.6°N 111.9°E – 70 kts 

  • 24 hrs: 21.1°N 109.7°E – 55 kts inland

  • 48 hrs: 20.3°N 106.9°E – 60 kts

  • 72 hrs: 19.7°N 103.9°E – 45 kts inland

  • 96 hrs: 20.0°N 101.7°E – 25 kts inland

  • 120 hrs: Dissipated

JTWC forecast map