Severe Tropical Storm Krosa (12W) – Tropical Cyclone Advisory #19: 1200 UTC 1 August 2025

Outer rainbands of Krosa moving over southeastern Honshu.

Author

Will Weaver
August 01, 2025

…Outer rainbands of Krosa moving over southeastern Honshu…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 34.6°N 141.3°E

  • Movement: N at 10 knots (20 km/h)

  • Intensity: 60 knots (110 km/h)

  • Central pressure: 975 hPa

Trend:

  • Little change in strength is forecast during the next 24 hours, but Krosa could become a typhoon later tonight or on Saturday.

Watches and warnings:

  • Yokosuka Naval Base is under TCCOR 4.

Hazards affecting land:

  • Although Krosa is forecast to remain offshore, there is still a chance it could pass close enough to Honshu to produce tropical storm conditions along the southeastern coast. U.S. military interests can get additional information from the Stars & Stripes Pacific Storm Tracker: https://www.stripes.com/theaters/asia_pacific/storm_tracker/

Discussion:

Krosa is currently making its closest approach to Japan. Radar data indicates that its outermost rainbands are over southeastern Honshu with most of the heavy rain located east of Tokyo. The storm itself has changed little in organization since the previous advisory, with some ragged bands of convection surrounding a large partial eyewall feature, with dry air entrainment evident in the southern and eastern sectors. This convection is being enhanced by strong radial outflow in all quadrants with favorable upper-level divergence, as well as a tongue of warmer SSTs just off Honshu. The intensity is increased to a possibly conservative 60 kts, based on Dvorak estimates ranging from T3.5 to T4.0, and a CIMSS D-PRINT estimate of 58 kts. The estimate is conservative as a recent RCM-1 SAR pass found typhoon force winds in the quadrants of the storm it actually sampled.

Composite radar image (CyclonicWx)

Krosa is moving northward, but it has begun to slow down again, suggesting that it is approaching the northwestern periphery of the mid- to upper-level ridge anchored over the west central Pacific. This ridge is currently in the process of being eroded by a trough approaching from the west, and the result is that Krosa should turn sharply toward the east-northeast during the next 12 to 24 hours. Although the environment is favorable for strengthening with low shear and warm waters, Krosa’s slow movement may cause more subsurface upwelling that could offset those favorable conditions. Therefore, little change in strength appears likely during the next day or two, although Krosa could become a typhoon again before it moves over cooler SSTs on Sunday. As Krosa accelerates into the mid-latitude westerlies, it should steadily weaken as it crosses over even colder waters and interacts with a deep low pressure area over the Bering Sea, and Krosa should become a post-tropical cyclone by Tuesday just before it exits the basin.

Forecast positions and maximum winds

  • 00 hrs: 34.6°N 141.3°E – 60 kts

  • 12 hrs: 36.0°N 142.5°E – 60 kts

  • 24 hrs: 37.4°N 145.3°E – 60 kts

  • 48 hrs: 40.1°N 156.2°E – 50 kts

  • 72 hrs: 42.5°N 166.1°E – 40 kts

  • 96 hrs: 43.8°N 177.0°E – 35 kts Post-tropical/extratropical

  • 120 hrs: 44.5°N 174.5°W – 30 kts Post-tropical/extratropical

Forecast track map