Tropical Depression (Invest 98W) – Tropical Cyclone Advisory #1: 0000 UTC 1 November 2025

…Tropical depression forms just east of Yap State…

Current storm information:

• Position: 9.4°N 139.3°E

• Movement: NNW at 5 knots (10 km/h)

• Intensity: 30 knots (55 km/h)

• Central pressure: 1008 hPa

Trend:

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

Discussion:

The area of low pressure located east of the islands of Yap State has continued to get better organized at a fairly quick rate during the past day or so. The low-level circulation center has continued to become better defined, and convection is organized into discrete bands beginning to wrap into it. The system is somewhat large and sprawling, and a recent HYSAT pass indicated that it had a very broad wind field with a large swath of 25 to 30 kt winds primarily to the south and southwest of the center. The system is receiving Dvorak fixes of T1.5 from KNES and T2.0 from RJTD, and so the system is upgraded to a tropical depression with wind of 30 kts.

This system has had a lot of hype associated with it, and for good reason, because it will be moving into a generally favorable environment as it traverses the Philippine Sea. SSTs are quite warm, the shear is expected to decrease, and there should be strong outflow channels. However, the HAFS-A dynamical and GFS and ECMWF deterministic models are not very enthusiastic and show only gradual strengthening during the next few days. The GFS and ECMWF ensembles do suggest a stronger system, but there is a tremendous amount of spread in the intensity guidance. If you include the Google DeepMind ensemble (which has been the reason for the hype around this system), the intensities range from 898 to 1004 hPa during the next 72 hours. I think it’s possible that Google DeepMind is overdoing the intensity, especially given that there will be another developing tropical cyclone to the east by Monday. However, the intensities listed below are somewhat higher than the JMA forecast and indicate 98W reaching typhoon strength as it approaches the Philippines and being at about that intensity by the end of the period. It’s going to be a little while before we have a better idea of what we’re dealing with.

Forecast positions and maximum winds

• 000 hrs: 9.4°N 139.3°E – 30 kts

• 012 hrs: 10.2°N 138.1°E – 30 kts

• 024 hrs: 10.9°N 135.9°E – 40 kts

• 048 hrs: 11.1°N 131.5°E – 50 kts

• 072 hrs: 10.8°N 126.2°E – 65 kts

• 096 hrs: 11.8°N 121.4°E – 65 kts

• 120 hrs: 12.2°N 116.7°E – 65 kts