Tropical Storm Co-May (11W/#Emong) – Tropical Cyclone Advisory #7: 1200 UTC 25 July 2025

Co-May becoming poorly organized as it accelerates away from Luzon.

Author

Will Weaver
July 25, 2025

…Co-May becoming poorly organized as it accelerates away from Luzon…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 21.4°N 123.7°E

  • Movement: NE at 24 knots (45 km/h)

  • Intensity: 40 knots (75 km/h)

  • Central pressure: 990 hPa

Trend:

  • Continued rapid weakening is forecast during the next 24 hours, and Co-May could dissipate on Saturday.

Watches and warnings:

PAGASA wind signal map (click to enlarge)

  • TCWS #1 (Philippines): Batanes Islands, Babuyan Islands, far northeastern Cagayan

Hazards affecting land:

  • Co-May and its remnants could produce heavy rain and gusty winds over the eastern coast of Taiwan and the Yaeyama Islands during the next day or so.

Discussion:

Himawari-9 infrared satellite image (Weathernerds). The circulation of Co-May is actually not underneath the mass of convection just southeast of Taiwan.

Co-May has completely decoupled as it accelerates northeastward within the monsoon trough extending over the western portion of the Philippine Sea. Its circulation center has become completely exposed well to the east of a persistent area of convection located just southeast of Taiwan, which is associated with Co-May’s mid-level circulation. The surface circulation has become somewhat diffuse and difficult to identify on conventional satellite imagery, though it is easier to make out on simulated microwave imagery. The intensity is lowered to 40 kts, mainly based on scatterometer data and is consistent with CIMSS ADT, D-PRINT, and SATCON estimates.

Simulated 89 GHz microwave image (RAMMB). The circulation of Co-May is the faint swirl located east of the southern tip of Taiwan. Also note the circulation of Francisco, north of Taiwan.

Co-May is in the process of being swept up into the large monsoonal circulation centered near Taiwan, and it is forecast to continue rocketing to the northeast. Increasing shear should continue to rip the storm apart during the next day or so, and most of the model guidance suggests that Co-May’s circulation will become stretched out and absorbed into the monsoon trough by Saturday evening as it nears the Yaeyama Islands. Some of the model guidance seems to suggest restrengthening early next week, but these seem to be latching onto a new circulation that is unrelated to Co-May.

Forecast positions and maximum winds

  • 00 hrs: 21.4°N 123.7°E – 40 kts

  • 12 hrs: 25.1°N 124.6°E – 40 kts

  • 24 hrs: Dissipated

JMA forecast map