Severe Tropical Storm Krosa (#12W) – Tropical Cyclone Advisory #13: 1200 UTC 29 July 2025

Krosa going nowhere fast as it meanders near the Ogasawara Islands.

Author

Will Weaver
July 29, 2025

…Krosa going nowhere fast as it meanders near the Ogasawara Islands…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 28.7°N 142.9°E

  • Movement: N at 1 knot (2 km/h)

  • Intensity: 50 knots (95 km/h)

  • Central pressure: 984 hPa

Trend:

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

Watches and warnings:

  • There are no land-based watches or warnings in effect.

Hazards affecting land:

  • Interests in mainland Japan should monitor the progress of Krosa. Krosa could make a close approach to southeastern Honshu this weekend, which could result in heavy rain and gusty winds, mainly east of Tokyo.

Discussion:

Himawari-9 infrared satellite image (Weathernerds)

Krosa remains a rather disheveled looking tropical storm due to the combined effects of subsurface cold water upwelling and a dry air mass nearby. The storm consists of some rather skeletal bands of convection mainly in the northern semicircle. Notably, Krosa’s internal structure has improved a little, with some convective bands wrapping around the center as a rudimentary eyewall feature. Still, there is significant dry air entrainment within the system and this has been choking off convective development elsewhere within Krosa’s circulation. Given the overall lack of convection, most Dvorak fixes and automated estimates are not particularly impressed with Krosa, but Oceansat-3 and ASCAT data suggest the winds are around 50 kts.

Synthetic 37GHz microwave satellite image (RAMMB/CIRA)

Krosa is not currently in much of a hurry to go anywhere. Steering currents are relatively weak due to multiple competing steering influences - the weakening monsoonal circulation to the southwest, a developing subtropical ridge over the Sea of Japan, and another subtropical ridge over the north Pacific. Because of this, Krosa will probably continue to linger near its current location for another day or two. The ridge to the northeast is forecast to weaken during the next couple of days, and this will cause the ridge over the Sea of Japan to become the dominant steering mechanism. Krosa’s forecast track has been shifted significantly to the west of the previous one and now shows a northwestward track toward Honshu. This will also enable some restrengthening as Krosa will be moving out of its own cold wake and into a more moist environment, and Krosa could be near or at typhoon strength by Saturday. On Saturday, an approaching trough should turn Krosa north, then northeastward just off the coast of Honshu, and gradually cooling SSTs should induce the beginnings of a final weakening trend toward the end of the forecast period.

Forecast positions and maximum winds

  • 00 hrs: 28.7°N 142.9°E – 50 kts

  • 12 hrs: 28.8°N 142.9°E – 50 kts

  • 24 hrs: 29.0°N 143.0°E – 55 kts

  • 48 hrs: 30.2°N 142.6°E – 65 kts

  • 72 hrs: 32.7°N 140.0°E – 65 kts

  • 96 hrs: 35.1°N 140.3°E – 60 kts

  • 120 hrs: 37.4°N 146.5°E – 50 kts

JMA forecast map