Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
378 FXPQ50 PGUM 111834 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 434 AM ChST Wed Nov 12 2025 .Marianas Update... Partly cloud skies with isolated showers are expected to continue through the weekend as a dry trade-wind pattern remains entrenched across the region. Gentle to moderate trade winds will continue through the weekend as well. Latest buoy and altimetry data show seas between 4 and 7 feet across the waters. Seas will subside over the next couple of days, then build again near the end of the week. && .Tropical Systems... A weak disturbance, Joint Typhoon Warning Center`s (JTWC) Invest 91W, is centered near 2N141E. Latest model guidance shows little, if any, development with this circulation. However, the latest ASCAT analysis does show some good winds to the south of the center. 91W looks to continue to move slowly northwest. Although development is not expected, Invest 91W will be monitored closely over the next couple of days. && .Eastern Micronesia Update... A dry trade-wind pattern stretches across the Marshalls into Kosrae and far eastern Pohnpei State. The only significant convection is seen to the east of the Marshalls along a weak Inter-Tropical Convergence Zone (ITCZ). Latest model guidance shows this ITCZ strengthening over the next few days, however, the models have been showing increased convergence across the area for the last couple of days that has not yet materialized. Therefore, convection may need to be decreased for the next couple of days. At Pohnpei, a weak trade- wind trough is generating scattered showers and isolated thunderstorms across the island today. The rest of the forecast remains unchanged. && .Western Micronesia Update... JTWC`s Invest 91W is found to the south-southeast of Yap Proper. The circulation has moved slowly toward the northwest. Scattered showers and isolated thunderstorms seen to the northwest through north of the circulation look to move into Yap Proper and Palau later this morning or early afternoon. For Chuuk, a dry trade-wind pattern remains over Weno, with scattered showers and isolated thunderstorms to the east expected to move over Chuuk Lagoon this evening. && .Prev discussion... /issued 544 PM ChST Tue Nov 11 2025/ Marianas Synopsis... Satellite imagery shows mostly sunny skies with small short-lived fast-moving isolated showers. Altimetry shows combined seas of about 7 feet while buoy data shows sea heights of 6 to 7 feet. Discussion... Peasant weather is expected for the Marianas with mostly sunny skies and short-lived fast-moving isolated showers for the remainder of the week. Winds of 10 to 15 mph are expected too. Marine... Gentle to moderate trade winds are expected to prevail through he weekend. Combined seas of 5 to 7 feet made up of a weakening trade swell, a strengthening north swell and a persistent west swell will continue for the next few days with varying strength for the remainder of the week. This will keep the seas in a state of flux which could lead to slightly lower seas at times, however, seas are expected to reaming choppy as these swells continue to mix. A moderate risk of rip currents is expected along west, north, and east facing reefs of the Marianas for at least the next few days. Surf is expected to be elevated but remain below hazardous levels along all reefs for much of this week. Eastern Micronesia... Overall, an active pattern continues as the ITCZ (Inter-Tropical Convergence Zone is situated between 7N and 11N. Within this feature are a pair of troughs, one approaching Pohnpei and another departing Majuro. Additional troughs are seen upstream (east of the Date Line) as well. Thus, scattered showers and isolated thunderstorms will persist at Pohnpei and Majuro, with isolated showers increasing in coverage Wednesday night at Kosrae, as the ITCZ begins to settle south. As for winds and seas, light to gentle winds will prevail through the period with seas mainly in the 4 to 6 foot range. Western Micronesia... Satellite observations show scattered showers impacting Chuuk and Palau with isolated showers across Yap. Altimetry data shows combined seas between 4 and 6 feet for Palau and Yap, and 5 to 7 feet across Chuuk. Overall, an active pattern looks to continue across western Micronesia through much of the week before a drying trend looks to begin this weekend. A buffer circulation located near 1N142E is the main weather producer across the region. This feature looks to remain broad and week as it slowly moves westward near the equator. The buffer circulation will lead to scattered to numerous showers and isolated thunderstorms across Palau and Yap through Friday. No organized development of the buffer circulation is expected at this time. For Chuuk, trade-wind convergence is bringing scattered showers to the region. The forecast for Chuuk looks to remain fairly consistent over the next several days with several rounds of trade- wind convergence expected. This will keep Chuuk in predominately elevated scattered showers with 40 to 50 PoPs through Thursday night. Marine conditions have improved greatly across western Micronesia. The High Surf Advisory was expired at 5 PM ChST based on altimetry data and surf observations. Combined seas look to remain benign through the forecast period. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas/East and West Micronesia Update: Kleeschulte Marianas: Bowsher East Micronesia: Doll West Micronesia: Williams