Typhoon Koto (33W / ex-Verbena) – Tropical Cyclone Advisory #7: 0000 UTC 27 November 2025

…Koto strengthens some more as it passes north of the Spratly Islands… …Forecast to move erratically with fluctuations in intensity during the next few days…

Current storm information:

• Position: 13.2°N 114.2°E

• Movement: W at 5 knots (10 km/h)

• Intensity: 75 knots (140 km/h) [Category 1]

• Central pressure: 965 hPa

Trend:

• Little change in strength is forecast during the next 24 hours.

Discussion:

Koto is continuing to strengthen. Microwave satellite imagery - both live and simulated - indicates that Koto still sports a well-defined and closed eye feature, although most of the strongest convection remains located within the western half of the eyewall. Koto’s central dense overcast remains fairly symmetrical with intensely cold cloud tops - there are spots of below -90°C cloud tops within the eyewall. Koto’s poleward outflow channel has expanded significantly since the previous advisory and this has been holding the cooler, more stable air associated with the northeasterly cold surge at bay. The microwave satellite imagery does suggest that cold air is trying to work its way into the circulation, however, with an area of drier air situated to the southeast of the eye. The intensity is increased to 75 kts, hedged between Dvorak fixes of T5.0 from PGTW and RJTD, T4.5 from KNES, and slightly lower CIMSS ADT and D-PRINT estimates ranging from 65 to 69 kts.

Koto is becoming embedded within a col region between two upper-level ridges to the northwest and northeast as well as Tropical Depression Senyar in the Malacca Strait (which is technically now in the Western Pacific basin). Because of this, the typhoon has ground to a halt. Most of the model guidance indicates that Koto will more or less meander in the southern South China Sea through the end of the forecast period. Because of this slow, erratic motion, Koto should gradually begin to upwell cooler subsurface waters, which will interfere with its efforts to generate convection and allow the drier air associated with the cold surge to infiltrate the circulation. This should contribute to gradual weakening during the next few days, though the guidance suggests a bit of restrengthening early next week as Koto moves out of its own cold wake. Koto is expected to remain over water through the end of the forecast period.

Forecast positions and maximum winds (1-min)

• 000 hrs: 13.2°N 114.2°E – 75 kts 140 km/h 

• 012 hrs: 12.9°N 113.6°E – 70 kts 130 km/h

• 024 hrs: 12.5°N 112.8°E – 65 kts 120 km/h 

• 048 hrs: 12.8°N 112.2°E – 55 kts 100 km/h 

• 072 hrs: 13.7°N 112.3°E – 45 kts 85 km/h 

• 096 hrs: 13.9°N 111.2°E – 45 kts 85 km/h 

• 120 hrs: 13.8°N 109.5°E – 50 kts 95 km/h