Typhoon Krosa (12W) – Tropical Cyclone Advisory #11: 1200 UTC 28 July 2025

…Krosa stalling out again and weakening as it upwells cooler waters from under the sea surface…

Discussion:

Krosa has slowed down again as it enters a col region between a subtropical ridge to its east and a monsoonal circulation to the west. This has resulted in the typhoon beginning to upwell cooler water from below the sea surface. This upwelling, combined with the dry air already entrained within Krosa’s circulation, has resulted in Krosa losing a great deal of its convection, and convection is now limited to a fragmented ring broadly wrapping into the circulation center. Microwave satellite imagery indicates that the eyewall now consists of low clouds and probably no longer qualifies as an eyewall. The current intensity of 70 kts is based on Dvorak estimates of T4.0 to T4.5 from PGTW, KNES, and RJTD, although automated estimates are much lower owing to the lack of convection.

Most of the model guidance, including the dynamical HAFS and HWRF models, do not show steering currents restrengthening any time soon, and the forecast now shows Krosa meandering near the Ogasawara Islands during the next few days. Although the environment appears favorable with low shear and warm SSTs, dry air wrapping into the system from the north and continued upwelling will probably serve to weaken Krosa during that time, and Krosa will likely weaken to a tropical storm tomorrow. By Friday, an upper-level low forecast to form well northeast of Krosa and a trough approaching from the west should cause Krosa to begin moving again, and as it moves out of its own cold wake, Krosa will likely strengthen again. Krosa is forecast to reattain typhoon status as the forecast period ends.

Forecast positions and maximum winds

• 00 hrs: 27.2°N 144.1°E – 70 kts

• 12 hrs: 28.2°N 143.0°E – 60 kts

• 24 hrs: 28.4°N 142.3°E – 50 kts

• 48 hrs: 28.6°N 142.3°E – 45 kts

• 72 hrs: 28.8°N 142.7°E – 50 kts

• 96 hrs: 30.6°N 142.0°E – 55 kts

• 120 hrs: 32.9°N 141.9°E – 65 kts