Typhoon Co-May (11W/#Emong) – Tropical Cyclone Advisory #5: 1200 UTC 24 July 2025

Co-May about to make landfall in northwestern Luzon.

Author

Will Weaver
July 24, 2025

…Co-May about to make landfall in northwestern Luzon…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 16.4°N 119.1°E

  • Movement: E at 5 knots (10 km/h)

  • Intensity: 65 knots (120 km/h) - Category 1

  • Central pressure: 975 hPa

Trend:

  • Little change in strength is likely before Co-May makes landfall. Rapid weakening is forecast thereafter.

Watches and warnings:

PAGASA wind signal map (click to enlarge)

  • TCWS #4 (Philippines): Southwestern Ilocos Sur, northwestern La Union, northwestern Pangasinan

  • TCWS #3 (Philippines): Southern Ilocos Norte, Abra, the rest of Ilocos Sur, western Mountain Province, eastern La Union, western Benguet, western Pangasinan

  • TCWS #2 (Philippines): Babuyan Islands, northern Ilocos Norte, Apayao, northern and western Cagayan, Kalinga, central and eastern Mountain Province, Ifugao, eastern Benguet, western Nueva Vizcaya, eastern Pangasinan, northern Zambales

  • TCWS #1 (Philippines): Batanes Islands, southeastern Cagayan, western and central Isabela, Quirino, eastern Nueva Vizcaya, northern and central Nueva Ecija, Tarlac, southern Zambales, northern Bataan, western Pampanga

Hazards affecting land:

  • An enormous amount of rain has fallen on portions of northern and western Luzon, and Co-May is expected to exacerbate this situation both directly and through enhancement of the monsoon trough. An additional 200 to 250 mm of rainfall is possible over western coastal areas of northern and central Luzon through Saturday. This rainfall is expected to contribute to widespread, life-threatening flooding in vulnerable areas. In addition, Co-May is likely to bring typhoon conditions to portions of Ilocos Sur, La Union, and Pangasinan, and strong tropical storm conditions to much of the rest of northwestern Luzon. This is a particularly dangerous and life-threatening situation! For additional information, including rainfall and flood warnings, refer to Weather Advisories and Severe Weather Bulletins from PAGASA or products from your local weather office.

Discussion:

Himawari-9 infrared satellite image (Weathernerds)

A couple of hours after the previous advisory, Co-May became severely disrupted, with erosion of the central dense overcast and the eye feature disappearing. This is likely due to a burst of mid-level northeasterly shear that occurred as a result of a deep-layer trough well to the north. In the past few hours, however, this shear appears to have relaxed, and Co-May’s structure has improved accordingly. Intense convection has redeveloped within the central dense overcast and is once again wrapping around the center, and microwave satellite imagery indicates that a complete eyewall feature has once again formed, and this eyewall is showing up on PAGASA radar just off the coast of the western tip of Pangasinan. The intensity is lowered slightly to 65 kts, based on consensus Dvorak fixes of T4.0 from all the agencies.

F-18 SSMIS 91 GHz microwave image, showing a mostly complete eyewall surrounding a very small eye feature

Co-May will be making landfall in Pangasinan and/or La Union during the next few hours. Although the environment is quite favorable with low shear and very warm SSTs, no appreciable change in strength appears likely before then. After landfall, Co-May should begin to accelerate northeastward into the strong southwesterly monsoon flow, weakening rapidly as it passes over rugged terrain. Co-May should emerge back over water near the Babuyan Islands late Friday morning, but the weakening should continue as the shear increases and Co-May’s circulation elongates and becomes incorporated into the larger monsoonal system. Although the forecast track shows positions over Okinawa and the East China Sea on Saturday night and Sunday, it is likely that Co-May will have ceased to be a distinct entity by then, although it will retain gale-force winds through the end of the weekend.

Forecast positions and maximum winds

  • 00 hrs: 16.4°N 119.1°E – 65 kts on the coast

  • 12 hrs: 18.7°N 121.7°E – 55 kts near the Babuyan Islands

  • 24 hrs: 22.2°N 124.3°E – 45 kts

  • 48 hrs: 27.1°N 128.4°E – 35 kts 

  • 72 hrs: Dissipated

JMA forecast map