Tropical Weather Discussion
Issued by NWS
Issued by NWS
394 AXPQ20 PGUM 032344 TWDPQ Tropical Weather Discussion National Weather Service Tiyan GU 944 AM ChST Thu Dec 4 2025 Tropical Weather Discussion for the Western North Pacific between the Equator and 25N from 130E to 180. The following information is based on recent satellite imagery/data, weather observations, radar, and meteorological analysis. ...SPECIAL FEATURES... TROPICAL AND MONSOON DISTURBANCES... JTWC`s Invest 93W is currently located near 13N131E. Invest 93W is currently rated medium for development, which means TC development is likely, but is expected to occur beyond 24 hours. Structually 93W has improved in organization with a persistent but slightly sheared Central Dense Overcast (CDO). Invest 93W will exist our Area of Responsibility (AOR) later today or tonight as it continues to organize. ...OTHER WEATHER SYSTEMS... NEAR EQUATORIAL TROUGH... The NET remains across western Micronesia extending from Invest 93W near 13N131E southeast towards a weak circulation near Yap, or 9N136E. The NET continues southeastward until it meets the equator at 153E. An active band of convection is seen north of the NET with scattered to numerous showers and isolated thunderstorms seen near Weno extending west-northwest to the south of Guam and to the northeast of Yap. Over the coming days the NET looks to re-orient closer to the Equator after 93W moves out of the region. TRADE-WIND TROUGHS... There are two trade-wind troughs across the region. The first trough is located east of the Marshall Islands, extending from 3N173E to 8N172E. This trough is interacting with an ITCZ fragment to produce scattered showers and isolated thunderstorms. The second trade-wind trough is seen just south of Kosrae extending from 2N164E to 6N162E. Isolated to scattered showers and isolated thunderstorms are seen along this trough. Both trade-wind troughs will move westward over the coming days as they weaken. TRADE-WIND Surge... A trade-wind surge is present north of eastern Micronesia. A distant surface high pressure has led to a tightening of pressure gradient. This is produing a large swath of 20 to 24 kt winds. Over the coming days the trade-wind surge will shift into eastern Micronesia as it starts to weaken. OTHER SYSTEMS... A frontal system remains draped across our northern region with a cold front entering our AOR at 25N140E and then decaying near 20N135E. Scattered showers and isolated thunderstorms are seen along the leading edge of the cold-front where it is interacting with outflow from Invest 93W. ...ITCZ... The ITCZ has continued to fragment and now remains generally east of the Marshal Islands entering the region at 2N180, extending to 5N172E. The ITCZ is expected to continue to weaken as the NET expands over eastern Micronesia. $$ Williams