WPAC Tropical Weather Outlook: 7/20/25

Active tropical cyclones:

• Severe Tropical Storm Wipha (09W), located inland over southern China near the Leizhou Peninsula. Refer to tropical cyclone advisories.

Disturbances/invest areas:

• Invest 97W (central Philippine Sea): A monsoonal area of low pressure has formed over the central Philippine Sea along the eastern periphery of a large monsoon gyre. This low is expected to become the dominant feature within the gyre as it moves generally northwestward, and a tropical depression is likely to form by Tuesday as the system approaches the Yaeyama and Ryukyu Islands. Interests in those islands, including Okinawa, should monitor the progress of this system.

  Formation chance through 48 hours: MEDIUM - 50% 🟠

  Formation chance through 7 days: HIGH - 80% 🔴

• Disturbance A (east of northern Luzon): Another area of low pressure embedded within the monsoon gyre over the western and central Philippine Sea is producing a large area of strong showers and thunderstorms. This low is expected to become incorporated into 97W during the next couple of days, and is not likely to become a tropical cyclone in its own right before then. However, it is expected to contribute to increased monsoonal rainfall over northern and central Luzon during the next couple of days.

  Formation chance through 48 hours: LOW - 10% 🟡

  Formation chance through 7 days: LOW - 10% 🟡

• Disturbance B (near Pohnpei): A large area of disturbed weather located over western Micronesia is associated with a trough of low pressure. An area of low pressure is forecast to form along this trough by midweek, and environmental conditions are likely to be conducive for development. A tropical depression is likely to form by Thursday or Friday as the system moves generally northward over open waters.

  Formation chance through 48 hours: LOW - 10% 🟡

  Formation chance through 7 days: HIGH - 70% 🔴

• Disturbance C (southwest of Guam): Another low pressure area is expected to form along the monsoon trough southwest of Guam by midweek. Environmental conditions will likely be conducive for development, and a tropical depression could form by the end of the week as it moves northward over open waters. By this weekend, this system will likely interact with and be absorbed by Disturbance B, which will end its development chances.

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

  Formation chance through 7 days: MEDIUM - 60% 🟠