Tropical Storm Krosa (12W) – Tropical Cyclone Advisory #23: 1500 UTC 3 August 2025

…Krosa still a tropical cyclone for now but expected to become post-tropical on Monday…

Current storm information:

• Position: 41.5°N 159.0°E

• Movement: ENE at 24 knots (45 km/h)

• Intensity: 50 knots (95 km/h)

• Central pressure: 979 hPa

Trend:

• Gradual weakening is expected during the next 24 hours, and Krosa will likely become a post-tropical cyclone on Monday.

Discussion:

Despite moving over rapidly cooling SSTs, Krosa is continuing to produce deep convection fairly near its center. However, Krosa’s circulation is beginning to decouple, with the mid-level circulation being displaced slightly to the east of the low-level circulation center. In spite of being vertically tilted, the low-level circulation remains fairly well defined, and although the poleward outflow channel is embedded within a frontal boundary, the fronts do not appear to have attached to the center yet. Cyclone phase diagrams suggest Krosa continues to have a deep warm core, so it remains a tropical cyclone for now. The intensity remains 50 kts based mainly on scatterometer data.

There are no changes to the forecast. Krosa should continue racing east-northeastward during the next couple of days, and it is expected to become a post-tropical cyclone within the next 12 to 24 hours. Post-tropical Krosa should then exit the basin on Tuesday before it merges with a large extratropical low over the southern Bering Sea.

Forecast positions and maximum winds

• 00 hrs: 41.5°N 159.0°E – 50 kts

• 12 hrs: 42.6°N 163.5°E – 45 kts

• 24 hrs: 43.5°N 169.5°E – 40 kts Post-tropical/extratropical

• 48 hrs: 45.0°N 175.0°W – 35 kts Post-tropical/extratropical

• 72 hrs: 53.6°N 165.1°W – 35 kts Post-tropical/extratropical

• 96 hrs: Absorbed by larger extratropical low