Tropical Storm Koto (33W / Verbena) – Tropical Cyclone Advisory #5: 0000 UTC 26 November 2025

Koto strengthening as it moves away from Palawan... Expected to strengthen but move erratically during the next few days...

Author

Will Weaver
November 25, 2025

…Koto strengthening as it moves away from Palawan… …Expected to strengthen but move erratically during the next few days…

Himawari-9 visible satellite image (Weathernerds)

Current storm information:

  • Position: 11.8°N 117.5°E

  • Movement: WNW at 14 knots (25 km/h)

  • Intensity: 55 knots (100 km/h)

  • Central pressure: 993 hPa

Trend:

  • Some strengthening is forecast during the next 24 hours, and Koto could become a typhoon on Thursday.

Watches and warnings:

PAGASA wind signal map (click to enlarge)

  • TCWS #2 (Philippines): Calamian Islands, far northern Palawan

  • TCWS #1 (Philippines): Kalayaan Islands, northern and central Palawan, Occidental Mindoro, Cuyo Islands

Hazards affecting land:

  • Interests in Vietnam should monitor the progress of Koto.

Discussion:

Although Koto appears to be a sheared system with cooler, stable air associated with the northeast monsoon very near its circulation, the tropical cyclone is getting better organized. Convection is continuing to increase in coverage and is sporting intensely cold cloud tops. Microwave satellite imagery indicates that a fragmented eyewall feature is present, with most of the convection west of the center. The cold surge is impinging upon the poleward outflow channel a bit, but Koto still sports strong dual channel outflow. A recent Sentinel-1 SAR pass indicates that the wind field is somewhat lopsided, but winds of 55 to 60 kts are occurring northwest of the center. Given this data and Dvorak fixes of T3.5 from PGTW and KNES, the intensity is increased to 55 kts. 

There are no major changes to the forecast for now. A shear line to the north is gradually eroding the subtropical ridge, which will result in steering currents collapsing. While this would normally cause a system to recurve, easterly flow associated with Tropical Cyclone 04B in the Malacca Strait will compete with the weakened ridge, and this will lead to Koto slowing down and moving very erratically west-northwestward during the next few days. The environment should be favorable for strengthening, and Koto is forecast to become a typhoon on Thursday before the northeasterly monsoon flow and cooling SSTs cause a weakening trend. Most of the model guidance suggests that Koto’s rate of weakening will likely level off as the northeasterly cold surge flow weakens over the weekend, and Koto will likely remain over water through the end of the period.

Forecast positions and maximum winds (1-min)

  • 000 hrs: 11.8°N 117.5°E – 55 kts 100 km/h 

  • 012 hrs: 13.0°N 115.6°E – 60 kts 110 km/h

  • 024 hrs: 13.0°N 114.5°E – 65 kts 120 km/h 

  • 048 hrs: 12.4°N 113.3°E – 65 kts 120 km/h 

  • 072 hrs: 12.5°N 112.9°E – 55 kts 100 km/h 

  • 096 hrs: 13.5°N 113.0°E – 50 kts 95 km/h 

  • 120 hrs: 13.6°N 112.5°E – 50 kts 95 km/h 

JMA forecast map