662 FXPQ50 PGUM 280847 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 647 PM ChST Sat Feb 28 2026 .Marianas Synopsis... Satellite imagery shows mostly cloudy skies over Guam and Rota and partly cloudy skies over Tinian and Saipan. Radar imagery shows scattered showers and isolated thunderstorms over Guam and Rota, and isolated showers over Tinian and Saipan. && .Discussion... The showers associated with the passing trade-wind trough, that was talked about in the previous discussion, are lingering longer than previously thought. These showers are expected to linger over Guam and Rota for about 24 hours or so. Time heights shows a moist air mass over the islands for the lower 500 mb. Above 500 mb, a bit of drier air is suggested for most of next week. Once this trough passes, a trade-wind surge is anticipated to develop into the region. This surge is expected to bring breezy conditions to the Marianas. && .Marine... Elevated trade winds and swell continue to produce hazardous seas of 8 to 10 feet this evening and are expected to continue through at least Sunday afternoon. A Small Craft Advisory remains in effect through Sunday afternoon, then seas are expected to subside to below hazardous levels of 10 feet by around Sunday night and further decreasing to 5 to 7 feet next week. Moderate to fresh winds look to become gentle to moderate this evening. A trade-wind trough is moving through the region, bringing scattered showers, mainly across Guam and Rota waters. && .Eastern Micronesia... Short Term (Tonight through Sunday afternoon): The main forecast challenges were rainfall, seas, and surf concerns at Pohnpei and Kosrae through Sunday afternoon. Visible satellite imagery shows a semblance of a broad circulation south-southeast of Pohnpei/southwest of Kosrae near 3N159E. This feature is located along a surface trough that extends north from EQ159E to east of Pohnpei near 7N159E. Enhanced surface convergence is interacting with seasonably-moist PWATs (Precipitable Water value) near 2.5 inches. This is generating abundant cloud cover with locally heavy rainfall probable at times given cloud tops pushing -85 deg C from time to time. This convection has been episodic in nature today, as it has improved strength and vigor for 3 to 6 hours, then weakens for 6 to 12 hours as the atmosphere stabilizes due to convective overturning. We expect another intense flare up to develop near midnight near either location. As such, showers were increased to numerous coverage with 60 percent probabilities while adding in locally heavy wording. Altimetry also showed seas in excess of 10 feet just east of Pohnpei/northwest of Kosrae. With this in mind, we decided to extend the High Surf Advisory and Small Craft Advisory through 3 PM Sunday at Pohnpei. For Kosrae, the latest wave data showed seas of 8 to 9 feet nearby, with the numerical guidance showing a northeasterly swell around 40 or 50 degrees. Given the lower thresholds mentioned by the previous shift for east-facing reefs there, we opted to extend the High Surf Advisory through 3 PM Sunday as well for Kosrae. Otherwise, look for winds and seas to gradually diminish Sunday evening through the middle of next week, with rainfall potential decreasing. At Majuro, the forecast through Sunday afternoon remains in good shape. Long Term (Sunday night through Thursday): Scattered showers and isolated thunderstorms will continue through Monday night, decreasing Tuesday into Wednesday, before increasing once again by Thursday. For the marine forecast, gentle to moderate winds at Pohnpei and Kosrae, with moderate to strong winds at Majuro, will gradually decrease through Tuesday, before increasing once again for the latter half of next week. Seas will gradually decrease through the forecast period. && .Western Micronesia... Latest satellite data shows cloudy skies with scattered showers and isolated thunderstorms over Chuuk, and partly cloudy skies with isolated showers over Palau and Yap. Scattered showers and isolated thunderstorms are developing southeast of Palau. Altimetry data shows seas of 8 to 10 feet over northern Chuuk waters, with seas of 7 to 9 feet at Yap and 6 to 8 feet at Palau. A Near-Equatorial Trough (NET) remains the focus over western Micronesia this evening. The NET stretches east across the region south of Palau to a broad circulation with two possible centers. A weak center is found southeast of Yap Proper near 6N141E, with the more prominent center found southwest of Weno, Chuuk near 6N147E. Latest model guidance shows the second, more prominent circulation developing very slowly over the next several days. This feature looks to intensify the NET to the west, while absorbing the other weaker circulation southeast of Yap Proper. As the circulation and NET slowly drift northwest, expect increasing convection across the region. High-end scattered showers and isolated thunderstorms are currently found over Weno, and this is expected to continue through the night, with showers becoming numerous by Sunday morning. Locally heavy showers are possible, along with gusts of 25 knots in heavier showers. The system is expected to move very slowly over the next week and will maintain a very active pattern across the state. If this scenario continues to develop as the models are predicting, a Special Weather Statement may be issued for Chuuk. For Palau, isolated showers this evening look to increase to scattered later tonight as the area of convection to the southeast approaches. The overall forecast for Palau looks to remain unsettled for the next several days due to the vicinity of the NET and the circulation southwest of Chuuk enhancing the convection. Due to uncertainty for the movement of the NET near Palau, maintained POPs (Probability of Precipitation) in the 40 percent range through the period. As things become more apparent, POPs may be increased or decreased. For Yap, most of the convection looks to remain south of Yap Proper, with only a few periods of 30 percent POPs through the coming week. This could change depending on the development of the NET and circulation southwest of Weno. For the marine forecast, altimetry shows seas remain elevated for Yap and Chuuk this evening, with seas of 8 to 10 feet for northern Chuuk waters and 7 to 9 feet at Yap. Based on model guidance and altimetry, decided to extend the Small Craft Advisory for Chuuk through Sunday afternoon. With the seas remaining elevated at both Yap and Chuuk, extended the High Surf Advisory through Sunday afternoon at Yap and through Monday morning at Chuuk. Gentle to moderate winds are expected through the week, with occasionally strong gusts to 25 knots at Chuuk with heavier showers Sunday and Sunday night. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...High Rip Current Risk through Monday afternoon for GUZ001. High Surf Advisory until 4 PM ChST Monday for GUZ001. MP...High Rip Current Risk through Monday afternoon for MPZ001>003. High Surf Advisory until 4 PM ChST Monday for MPZ001>003. Marianas Waters...Small Craft Advisory until 5 PM ChST Sunday for PMZ151>154. && $$ Marianas: Bowsher East Micronesia: Doll West Micronesia: Kleeschulte