Tropical Storm Wutip (01W) - Tropical Cyclone Advisory #4, 1200 UTC 6/11/25

…Wutip not well organized but hanging on as a tropical storm…

Current storm information:

• Position: 16.8°N 111.4°E

• Movement: WNW at 10 knots (20 km/h)

• Intensity: 35 knots (65 km/h)

• Central pressure: 992 hPa

Trend:

• Some gradual strengthening is forecast during the next 24 hours.

Watches and warnings:

• The No. 1 standby signal is active for Macau and Hong Kong.

Hazards affecting land:

• Wutip is likely to produce very heavy rainfall over portions of Hainan Island beginning on Thursday. This rainfall is expected to spread over southern China, including Macau and Hong Kong, by the end of the week and over the weekend. Since Wutip will be relatively slow-moving, this rainfall is likely to cause widespread severe flooding. For further information, including possible warnings, refer to products from your local weather office.

Discussion:

Wutip is not a well organized tropical storm. In fact, JTWC continues to warn on it as a tropical depression, and I’m honestly not surprised. The tropical storm consists of a mostly exposed low-level circulation center displaced to the northeast of some fragmented convective bands. CIMSS shear data and water vapor satellite imagery suggests that there is an elongated TUTT cell over southern China, which is producing about 20 to 25 knots of east-northeasterly shear of Wutip which is hampering its attempts to organize. Despite the shear, the circulation is fairly well defined and ASCAT data suggests that Wutip continues to produce a broad swath of 30 to 35 kt winds mainly to the west of the center. Based on this data, the intensity is held at 35 kts. This is slightly ahead of a CIMSS ADT estimate of 32 knots and a blend of Dvorak estimates from RJTD, KNES, and PGTW ranging from T1.5 to T2.5 (averaging out at 30 kts).

The TUTT cell to the north has been nudging Wutip further west than previously forecast, and the agencies have generally responded by adjusting their forecast tracks accordingly. The latest JMA forecast is slightly west of the previous one and shows Wutip gradually turning toward the northwest as the TUTT cell weakens and ridging builds in to the northeast. As the TUTT cell weakens, the shear plaguing Wutip should relax, and this should allow some modest strengthening. Wutip is likely to reach severe tropical storm status just before it makes landfall on Hainan Island early on Friday morning. It should be noted that the dynamical HWRF and HAFS-A guidance brings Wutip to typhoon intensity before then, but given Wutip’s current level of organization, this seems unlikely.

After passing over Hainan Island, land interaction will likely put an end to any strengthening. Although Wutip will move over the Gulf of Tonkin late Friday evening and Saturday morning, increasing shear and disruption from the passage over Hainan will likely preclude any restrengthening before it makes its final landfall west of the Leizhou Peninsula on Saturday evening. As Wutip makes landfall, it will begin interacting with the meiyu/tsuyu frontal boundary and begin undergoing extratropical transition. This interaction could maintain Wutip at tropical storm strength longer than would normally be expected after landfall, but Wutip is expected to become a post-tropical cyclone and merge with the front by the time it emerges from the eastern coast of China on Tuesday.

Forecast positions and maximum winds

• 00 hrs: 16.8°N 111.4°E - 35 kts

• 12 hrs: 17.1°N 110.4°E - 40 kts (near southern Hainan coast)

• 24 hrs: 17.8°N 109.7°E - 50 kts (over the Gulf of Tonkin)

• 48 hrs: 19.7°N 108.9°E - 50 kts

• 72 hrs: 22.6°N 110.3°E - 40 kts (inland)

• 96 hrs: 25.8°N 115.0°E - 35 kts Post-tropical/extratropical (inland)

• 120 hrs: 29.0°N 121.5°E - 30 kts Post-tropical/extratropical (inland)