Tropical Storm Co-May (11W/Emong) – Special Tropical Cyclone Advisory #3: 1800 UTC 23 July 2025

Co-May continues to rapidly intensify and is now near typhoon intensity. Signal #2 issued for parts of northwestern Luzon.

Author

Will Weaver
July 23, 2025

…Co-May continues to rapidly intensify and is now near typhoon intensity… …Signal #2 issued for parts of northwestern Luzon…

Himawari-9 infrared satellite image (Weathernerds)

Current storm information:

  • Position: 16.9°N 118.0°E

  • Movement: W at 8 knots (15 km/h)

  • Intensity: 60 knots (110 km/h)

  • Central pressure: 981 hPa

Trend:

  • Additional rapid strengthening is expected and Co-May will likely become a typhoon later today.

Watches and warnings:

PAGASA wind signal map (click to enlarge)

  • TCWS #2 (Philippines): Ilocos Sur, southern Abra, western Mountain Province, La Union, Benguet, western Ifugao, western Nueva Vizcaya, northern and northwestern Pangasinan

  • TCWS #1 (Philippines): Batanes Islands, Babuyan Islands, Ilocos Norte, Apayao, Cagayan, northern Abra, Kalinga, western and central Isabela, eastern Mountain Province, eastern Ifugao, central and eastern Nueva Vizcaya, northern Zambales, southern Pangasinan, Tarlac, northern and central Nueva Ecija

Hazards affecting land:

  • Co-May is expected to produce extremely heavy rainfall over much of Luzon and Mindoro, particularly along the western coasts. Many of these areas have already seen rainfall of up to 300 mm. Additional rainfall of up to 350 mm is possible through Saturday before the monsoon gyre finally breaks down, and this rainfall is expected to cause widespread severe to catastrophic flooding. In addition, Co-May is expected to strengthen rapidly and bring tropical storm or typhoon conditions to portions 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)

This special advisory is being posted to note a significant increase in Co-May’s intensity. JTWC’s best track data has been revised to indicate an intensity of 40 kts at 0600 UTC and 50 kts at 1200 UTC. Since then, the compact tropical cyclone has continued to become better organized. Although the eye is currently not distinct on conventional satellite imagery, 37 GHz microwave imagery from the ISS’s COVWR instrument indicates that the eyewall structure has improved quite a bit from earlier, and Co-May now sports a complete eyewall with a very small eye. However, the equatorward outflow channel has become somewhat restricted, likely due to a slight increase in easterly shear. Given the improved structure and Dvorak estimates of T3.5 from PGTW and KNES, the intensity is increased to 60 kts.

ISS COWVR 34 GHz microwave image of Co-May, showing a complete eyewall feature near its center

There are no changes to the forecast with the exception of higher intensities prior to landfall. The environment remains conducive for continued rapid intensification, and Co-May could be a strong typhoon by the time it makes landfall near Vigan overnight Thursday into Friday. The forecast continues to call for Co-May to decay into a trough south of the Yaeyama Islands on Saturday.

Forecast positions and maximum winds

  • 00 hrs: 16.9°N 118.0°E – 60 kts

  • 12 hrs: 16.7°N 119.0°E – 75 kts

  • 24 hrs: 17.4°N 120.4°E – 85 kts on the Luzon coast

  • 48 hrs: 23.1°N 125.7°E – 35 kts 

  • 72 hrs: Dissipated

JMA forecast map