WPAC Tropical Weather Outlook: 7/28/25

Co-May remains weak to the NW of Okinawa, Krosa is meandering near Iwo Jima, and a large belt of gale-force winds dominates the Philippine Sea. Hurricane Iona could enter the basin this weekend.

Author

Will Weaver
July 28, 2025

Active tropical cyclones:

  • Tropical Depression Co-May (11W), located west-northwest of Okinawa. Refer to tropical cyclone advisories.

  • Typhoon Krosa (12W), located east of the Ogasawara Islands. Refer to tropical cyclone advisories.

  • Hurricane Iona (01C) is located in the Central Pacific Basin about 1440 km southeast of Honolulu, Hawaii with winds of 65 kts. Iona is forecast to move across the Central Pacific basin during the next few days and could enter the Western Pacific basin on Saturday as a tropical storm. If it does, it will likely be in the process of weakening due to unfavorable environmental conditions. For additional information on Iona, refer to products from the U.S. Central Pacific Hurricane Center.

Disturbances/invest areas:

  • Disturbance A (well southeast of Okinawa): A monsoonal low pressure area is forecast to develop along the sprawling monsoon trough well to the southeast of Okinawa later this week. Any development of this system will likely be slow to occur due to unfavorable upper-level winds as it moves generally northeastward.

    Formation chance through 48 hours: VERY LOW - 0% ⚫

    Formation chance through 7 days: LOW - 10% 🟡

Non-tropical marine warnings (south of 30°N):

  • Gale warning for western and central Philippine Sea east of Luzon, southeast of Taiwan, and south of the Ryukyu Islands. Strong southwesterly monsoonal flow. SW winds 30 to 35 kts expected during the next 24 hours, easing below 30 kts by 0000 UTC 30 July 2025.