Tropical Weather Discussion
Issued by NWS
Issued by NWS
735 AXPQ20 PGUM 010101 TWDPQ Tropical Weather Discussion National Weather Service Tiyan GU 1101 AM ChST Tue Sep 1 2026 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... A monsoon disturbance, Invest 94W, remains NE of Luzon, centered near 22.0N 132.3E, moving slowly NNW. Invest 94W remains the subject of a Tropical Cyclone Formation Alert (TCFA) by the Joint Typhoon Warning Center (JTWC), meaning 94W is expected to become a significant tropical cyclone (tropical depression) within the next 24 hours. Invest 94W is seen as a broad, elongated circulation on the latest ASCAT and 925mb analyses, embedded along the monsoon trough. Scattered to numerous showers and scattered thunderstorms are seen to the S of 94W where the strongest convergence exists, with scattered showers and isolated thunderstorms found near the center outward about 160 miles, mainly W. Conditions remain favorable for 94W to develop as it continues to move slowly NNW. For more information on Invest 94W and the TCFA, see bulletins issued by JTWC under WMO headers ABPW10 PGTW and WTPN21 PGTW. A weak monsoon disturbance, Invest 95W and the TCFA, is seen along the monsoon trough to the E of Rota, centered near 14.1N 149.8E. 95W remains sub-low, meaning development is not expected for at least the next day or two. Convergence associated with 95W is generating scattered to numerous showers and isolated thunderstorms along a line to the N of the monsoon trough from the center of 95W to near 17N159E, to the NW of the center over the CNMI and SW of the center to 7N143E. Invest 95W will continue moving NNW over the coming days, likely passing through the northern CNMI as a weak disturbance, possibly as a Tropical Depression. Invest 95W will continue to be monitored for any indication that development will begin earlier or for any change in expected track. ...OTHER WEATHER SYSTEMS... MONSOON TROUGH... The monsoon trough crosses 130E near 23N, extending ESE through Invest 94W, across the CNMI N of Saipan, to Invest 95W. It then turns E to 15N163E where it turns SE to just N of Majuro. It then makes another turn toward the E, crossing the Date Line near 8N. Most of the convection associated with the monsoon trough is found with both Invest 94W and Invest 95W. Enhanced convergence produced by Invest 94W is generating scattered to numerous showers and scattered thunderstorms S of Invest 94W, as mentioned above. Farther E, convection associated with Invest 95W is seen over the Marianas and farther E, also described above. Spotty showers are found S of the trough, N of Weno, Chuuk and Pohnpei. From N of Kosrae to Majuro, scattered showers are found along and just S of the trough. Convection again becomes spotty E of Majuro. The monsoon trough looks to remain quasi-stationary over the next few days, with little change in intensity, except near the two invests. The invests will pull the associated portions of the trough slowly N with a little bit of strengthening as they slowly develop. SURFACE TROUGHS... A surface trough is seen to the SE of Guam to W of Weno, Chuuk, extending SSE from near 12N146E to end near 7N148E. Enhanced convergence W of the trough is generating scattered to numerous showers and isolated thunderstorms between Yap and Weno, between 6N and 12N. This trough will move ENE over the next couple of days, possibly interacting with the monsoon trough in a couple of days, increasing convection along the trough. A small surface trough is seen extending SW from a weak circulation centered NE of Wake Island near 21N168E. Scattered to numerous showers and isolated thunderstorms are found within an area of enhanced convergence associated with this trough. The trough and circulation will move toward the NE over the next couple of days, with a slight increase in intensity. $$ Kleeschulte