037 FXPQ50 PGUM 030824 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 624 PM ChST Fri Oct 3 2025 .Marianas Synopsis... Satellite imagery shows partly cloudy skies, while radar imagery shows isolated showers over the Marianas. Altimetry shows combined seas of 2 to 4 feet, while buoy data shows sea heights of about 2 to 3 feet. && .Discussion... Island convection is expected to be the main concern for the next few days due the the light and variable winds that are expected. This is expected through the weekend until the trade-wind trough that is currently north of Pohnpei Island moves into the region. This trough is expected to bring scattered showers and isolated thunderstorms to the region. The arrival time of this trough is around the beginning to middle of next week. Pleasant weather may return once this trough passes. && .Marine... Light winds and combined seas of 2 to 4 feet are expected through Wednesday. Winds will become light to gentle Monday. An approaching TUTT cell is expected to increase the risk of thunderstorms across the waters over the next couple of days. Island heating could give rise to thunderstorms near Guam for Saturday and Sunday afternoons. There will be a low risk of rip currents along all reefs of the Marianas through the end of next week. There will also be a moderate risk of lightning on Saturday through Tuesday for Guam. .Tropical Systems... There is a weak circulation within a broad, elongated trough centered near 20N147E just north-northwest of the northern CNMI, which is being monitored by the Joint Typhoon Warning Center (JTWC) as Invest 94W. 94W is categorized as a sub-low, meaning development into a significant tropical cyclone is not expected within the next 24 hours. There is a broad area of enhanced 850 mb vorticity co-located with the disturbance, but the overall system remains highly disorganized. Numerous heavier showers are seen within the area of convergence along 94W's eastern flank, with just isolated to scattered showers seen near the center, mainly just to its north. 94W looks to gradually shift westward over the next day or so as it morphs into a broader cyclonic turning over the eastern Philippine Sea, merging with a weaker circulation currently centered near Yap. Invest 94W and the emerging pattern over the Philippine Sea will continue to be monitored for development over the next few days. && .Eastern Micronesia... An active pattern is seen across eastern Micronesia this afternoon. A fragmented Inter-Tropical Convergence Zone (ITCZ) is seen across the region, stretching from Pohnpei, across Kosrae to end south of Kwajalein. Two robust trade-wind troughs are interacting with the ITCZ to generate numerous showers and isolated thunderstorms across Kosrae and widespread showers and isolated thunderstorms across Pohnpei. Kosrae is currently on the eastern edge of the numerous showers, with convection expected to decrease through the evening, becoming scattered by midnight, then isolated Saturday afternoon. Pohnpei looks to keep widespread showers through the night, with coverage becoming scattered by Saturday morning, then isolated by afternoon. These changes are due to the troughs moving out of the region and the ITCZ drifting northward and weakening. For Majuro, isolated showers this afternoon look to increase to scattered with isolated thunderstorms during the evening as a weak trough that crossed the Date Line approaches the atoll. Increased convection is seen to the east, approaching the atoll. All three points then look to remain dry for a short time. Then, a series of weak troughs will bring increased convection to the region Sunday into next week. Majuro looks to begin to dry out early next week, with Kosrae following suit by midweek. Benign marine conditions look to continue into the middle of next week, with combined seas at or below 5 feet and mostly light to gentle winds across the region. && .Western Micronesia... The trough moving northwest across far western Micronesia yesterday has merged with a broad, very weak circulation currently centered near Yap at around 10N137E. An elongated trough extends far north- northeast from this feature, passing west of the Marianas where it connects with Invest 94W at around 20N147E, north-northwest of the northern CNMI. The circulation near Yap is convectively quiet this evening. Satellite shows isolated to scattered showers across the area including over Yap and Palau coastal waters, but most of the convection is well northwest of the circulation center where convergence is strongest. Models show little strenghening of this feature over the next few days as it begins to morph into a much broader cyclonic turning over the eastern Philippine Sea, where Invest 94W looks to make up the northern periphery of the broader circulation. This will support the strengthening of a southwest monsoon pattern over Yap and Palau early next week, leading to wetter conditions Monday through Wednesday. Showers will become numerous at times, mainly for Yap, with locally heavy showers possible. In the meantime, just isolated to scattered showers will continue through the weekend. To the east, widespread cloudiness is seen across Chuuk State extending across much of eastern Micronesia, with the highest cloud tops and heaviest showers well east of Chuuk Lagoon and adjacent waters. Showers are expected to remain scattered for Chuuk overnight with numerous showers further east. This weekend, a tropical disturbance looks to develop just east of Chuuk, shifting northwest across the area through early next week as it passes near the Marianas. Model trends have been keeping Chuuk along the periphery of the developing disturbance, but locally heavy showers will be possible through the weekend. Scattered showers will continue through early next week as a fragment of the ITCZ lifts northwest into the area. Benign marine conditions continue. Altimetry data indicates combined seas of around 2 to 4 feet across the region, comprised of a primary northeast to east trade swell. There is little change expected heading into the weekend. Early next week, a pulse of elevated southwest swell looks to build across Palau waters, driven by a developing monsoon-like pattern, but no marine or surf hazards are expected at this time. Winds will remain mostly light to gentle through the weekend, becoming moderate at times early next week as the monsoon-like pattern strengthens. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Bowsher East Micronesia: Kleeschulte West Micronesia: DeCou