Severe Tropical Storm Krosa (12W) – Tropical Cyclone Advisory #21: 1200 UTC 2 August 2025

…Krosa accelerating off into the subtropical northern Pacific…

Current storm information:

• Position: 38.3°N 145.8°E

• Movement: ENE at 16 knots (25 km/h)

• Intensity: 55 knots (110 km/h)

• Central pressure: 972 hPa

Trend:

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

Discussion:

Krosa has made a bit of a comeback during the past 12 hours or so. Convection has redeveloped in the southern semicircle of the system, and the dry air that had been present has mixed out of the circulation. There are also hints of an eye feature trying to clear itself out on satellite imagery. Despite these improvements, however, there are also indications that Krosa is about to start extratropical transition. A front-like band continues to extend to the south of the system, and this band is also carrying Tropical Depression 13W along for the ride. Available scatterometer data also suggests the wind field is beginning to expand in the southeastern quadrant. The intensity remains 55 kts, based on consensus T3.5 Dvorak fixes and a 55 kt SATCON estimate.

There are no changes to the forecast. Krosa has about 12 hours left over favorable SSTs before crossing the northern extent of 26°C SSTs. Although shear has increased, Krosa’s acceleration within the shear vector is offsetting its effects, so the shear is unlikely to be a major factor in Krosa’s intensity. Little change in strength appears likely before Krosa moves over the colder waters, after which it should steadily weaken through the end of the forecast period. As Krosa races eastward, it should become entangled within a baroclinic zone and lose the rest of its tropical characteristics by Tuesday, just before it exits the basin. Post-tropical Krosa will likely continue to be a distinct entity through the end of the forecast period, when it will likely begin merging with a large low pressure area in the Bering Sea.

Forecast positions and maximum winds

• 00 hrs: 38.3°N 145.8°E – 55 kts

• 12 hrs: 39.9°N 150.8°E – 55 kts

• 24 hrs: 41.2°N 156.7°E – 50 kts

• 48 hrs: 42.9°N 167.4°E – 40 kts

• 72 hrs: 43.6°N 178.2°E – 35 kts Post-tropical/extratropical

• 96 hrs: 46.1°N 164.6°W – 30 kts Post-tropical/extratropical

• 120 hrs: 56.9°N 169.6°W – 35 kts Post-tropical/extratropical