Tropical Depression (Invest 90W/Nando) – Tropical Cyclone Advisory #3: 0000 UTC 18 September 2025

…Tropical depression in the central Philippine Sea starting to get better organized… …Forecast to become an intense typhoon by early next week…

Current storm information:

• Position: 15.0°N 133.1°E

• Movement: WNW at 9 knots (15 km/h)

• Intensity: 30 knots (45 km/h) 

• Central pressure: 1005 hPa

Trend:

• Some strengthening is forecast during the next 24 hours, and the depression could become a tropical storm later today.

Discussion:

The tropical depression in the central Philippine Sea (invest 90W) is starting to show some signs of getting better organized. Convection has increased in coverage and is starting to develop into discrete bands wrapping somewhat loosely into a partially exposed but well defined circulation center. There continues to be some northwesterly subsidence affecting the system and impinging upon its poleward outflow channel, which is continuing to hamper its efforts to organize. Although the depression is better organized, available scatterometer data does not indicate that it is producing tropical storm force winds yet, so the intensity is held at 30 kts.

The forecast is generally unchanged from the previous one. The depression will soon be moving into a more favorable environment for strengthening, and almost all of the available model guidance, including the HAFS, operational GFS and ECMWF, and GFS, ECMWF, and Google DeepMind ensembles suggest that the system will begin to rapidly intensify on Sunday. The depression is forecast to move generally west-northwestward in a rather erratic fashion as its circulation continues to become better defined. It will likely become a tropical storm later today. After it does, 90W is expected to run headlong into strong ridging over the subtropical Philippine Sea and turn more toward the west beginning on Sunday, which will also correspond with the most likely time for rapid intensification. Rapid intensification remains explicitly forecast and the wind values below are higher than the JMA forecast (after conversion to 1-minute winds), and it appears highly likely that 90W will be a very intense system by the end of the forecast period as it enters the Luzon Strait. The HAFS-A notably continues to make 90W a Category 5 system by the end of the forecast period.

It should be noted that it is still too soon to determine which areas could receive direct impacts from this system, as there is still some spread among the track guidance.

Forecast positions and maximum winds

• 00 hrs: 15.0°N 133.1°E – 30 kts

• 12 hrs: 15.8°N 132.4°E – 40 kts

• 24 hrs: 16.6°N 131.9°E – 50 kts

• 48 hrs: 17.1°N 130.8°E – 70 kts

• 72 hrs: 18.3°N 129.3°E – 95 kts

• 96 hrs: 19.2°N 125.5°E – 115 kts

• 120 hrs: 20.1°N 121.1°E – 125 kts