Tropical Storm Ragasa (24W/Nando) – Tropical Cyclone Advisory #5: 0000 UTC 19 September 2025

Ragasa gradually strengthening as it moves slowly westward. Expected to begin intensifying more rapidly on Saturday.

Author

Will Weaver
September 18, 2025

…Ragasa gradually strengthening as it moves slowly westward… …Expected to begin intensifying more rapidly on Saturday…

Himawari-9 visible satellite image (Weathernerds)

Current storm information:

  • Position: 15.7°N 131.9°E

  • Movement: W at 3 knots (5 km/h)

  • Intensity: 40 knots (75 km/h) 

  • Central pressure: 998 hPa

Trend:

  • Steady strengthening is forecast during the next 24 hours.

Watches and warnings:

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

Hazards affecting land:

  • Interests in the Batanes Islands, Babuyan Islands, and northern Luzon should closely monitor the progress of this system. Although it remains too early to determine what the extent of impacts will be, it is becoming very likely that an intense typhoon will affect that region early next week. Preparations to protect life and property should be underway.

  • Interests in southern China, including Hong Kong and Macau, should also monitor the progress of this system.

Discussion:

Ragasa has lost a little bit of organization since the previous advisory, and it appears to be in the midst of a center reformation. Persistent northwesterly subsidence associated with an upper-level ridge over the Taiwan Strait is continuing to displace Ragasa’s convection to the south and east of its apparent circulation center, which is almost fully exposed. However, in the past few hours, bursts of convection have developed a bit to the south and east of the apparent center location, suggesting that the center is reforming in that location, and this was actually fairly well predicted by most of the models. Despite the subsidence, Ragasa continues to have strong equatorward outflow, and the convection has continued to consolidate. Although Dvorak estimates only range from T2.0 to T2.5, scatterometer data indicates an area of 35 to 40 kt winds to the south of the center, so the intensity is increased to 40 kts.

The forecast track has been nudged slightly to the north as much of the model guidance has done the same, showing a track further north of mainland Luzon. Despite Ragasa’s current structure, all of the rapid intensification guidance continues to suggest that Ragasa will explosively intensify beginning on Saturday, and the HAFS-A model continues to bring Ragasa to Category 5 strength within the next 96 hours. With the current forecast track keeping Ragasa further north of a major landmass, the winds given below are higher than in the JMA and JTWC forecasts, and Ragasa could become a super typhoon as it enters the Luzon Strait on Monday evening. By Tuesday, a gap wind event in the Taiwan Strait will likely impact Ragasa and cause some weakening, but it is expected to remain a very intense typhoon as it approaches southern China and Hong Kong by the end of the forecast period.

It is still too soon to determine with any certainty what the extent of Ragasa’s effects will be, although it is becoming increasingly likely that a very intense and dangerous typhoon could affect the Batanes Islands, Babuyan Islands, and parts of coastal northern Luzon on Monday and Tuesday. 

Forecast positions and maximum winds

  • 00 hrs: 15.7°N 131.9°E – 40 kts

  • 12 hrs: 16.2°N 131.3°E – 50 kts

  • 24 hrs: 16.8°N 130.1°E – 70 kts

  • 48 hrs: 18.3°N 128.2°E – 100 kts

  • 72 hrs: 19.4°N 124.8°E – 130 kts

  • 96 hrs: 20.1°N 120.0°E – 125 kts

  • 120 hrs: 20.9°N 115.3°E – 115 kts

JTWC forecast map