Severe Tropical Storm Koto (33W) – Tropical Cyclone Advisory #13: 0000 UTC 30 November 2025

…Koto strengthens a little bit as it continues to go nowhere fast…

Current storm information:

• Position: 14.1°N 112.1°E

• Movement: Nearly stationary

• Intensity: 50 knots (95 km/h)

• Central pressure: 996 hPa

Trend:

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

Discussion:

Koto has gotten a bit better organized since the previous advisory, thanks to a trough digging down from the north that has disrupted the northeasterly cold surge that had been impacting it. Convection has begun wrapping around the eastern side of the circulation center and has re-consolidated into a ragged central dense overcast feature. Interaction with the trough is enhancing Koto’s radial outflow, although there is still a great deal of dry air in the area that is constraining convective development. Microwave satellite imagery depicts a partial eye feature, mainly along the eastern side of the circulation center. Dvorak estimates of T3.0 to T3.5 and ADT and D-PRINT estimates of 47 and 46 kts support increasing the intensity to 50 kts, making Koto a severe tropical storm again.

Koto’s renaissance is expected to be short-lived. While the environment is marginally favorable at the moment with low to moderate shear and 26-27°C SSTs, the upper-level trough is expected to lift out on Monday. Ridging will build in behind the trough, which will result in another strong northeasterly cold surge. This surge is expected to turn Koto sharply southwestward and rapidly strip it of its convection as it accelerates toward southern Vietnam. Simulated IR satellite imagery suggests that Koto will become a non-convective remnant low before moving inland, with the circulation dissipating as it makes landfall.

Forecast positions and maximum winds (1-min)

• 000 hrs: 14.1°N 112.1°E – 50 kts 95 km/h 

• 012 hrs: 14.3°N 112.5°E – 50 kts 95 km/h

• 024 hrs: 14.4°N 112.1°E – 50 kts 95 km/h 

• 048 hrs: 13.8°N 110.9°E – 40 kts 75 km/h 

• 072 hrs: 13.4°N 109.9°E – 30 kts 55 km/h Post-tropical/remnant low

• 096 hrs: Dissipated