Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
780 FXPQ50 PGUM 100710 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 510 PM ChST Sun Aug 10 2025 .Marianas Synopsis... Latest satellite and radar shows mostly cloudy skies with scattered showers and isolated thunderstorms across the CNMI. mostly cloudy skies with isolated showers are seen over Guam. Buoys show seas between 2 and 4 feet, while altimetry shows seas of 3 to 5 feet over the eastern waters. && .Discussion... Upper-level divergence associated with the TUTT (Tropical Upper Tropospheric Trough) moved over the Marianas, bringing scattered showers and isolated thunderstorms to the CNMI today and tonight. This convection is expected to spread south as the TUTT drifts west- southwest through the next couple of days. Scattered showers look to continue for the CNMI through Monday afternoon and should spread south over Guam by Monday morning. The TUTT will slowly move through the region, allowing showers to decrease to isolated Monday night, though thunderstorms will remain a possibility through Tuesday. For Guam, light and variable winds Tuesday and Wednesday will bring result in island convection during the afternoon on both days, and could occur again on Thursday. Otherwise, a dry trade-wind pattern is expected Tuesday night through the weekend. && .Marine... Light to gentle winds are expected through next week. Combined seas of 3 to 5 feet will slowly subside, dropping to between 2 and 3 feet by Thursday. An upper-level low will produce isolated thunderstorms through Tuesday. && .Tropical Systems... At 1:00 pm, Tropical Storm Podul (16W) was centered south-southwest of Iwo To near 22N138E. Podul is moving west across the Philippine Sea at 16 mph. Podul is expected to maintain this course with a decrease in forward speed. Maximum sustained winds are 65 mph. Podul is still expected to slowly strengthen, though it is not expected to become a typhoon until Monday night or Tuesday. For more information on Podul, please refer to bulletins from the Joint Typhoon Warning Center under WMO header WTPN32 PGTW and from the National Weather Service under WMO header WTPQ32 PGUM. && .Eastern Micronesia... An active, but fragmented Intertropical Convergence Zone (ITCZ) stretches across the region. The bulk of convection is focused around a broad trade-wind trough within the overall ITCZ pattern, extending through much of Kosrae State to the northern Marshalls. Numerous showers and isolated thunderstorms are expected for Kosrae through tonight, meanwhile Majuro is slightly east of the trough axis, although scattered showers and isolated thunderstorms are still expected, with both locations seeing occasional gusts to 20 kt near heavier showers through tonight. Patchier showers are seen ahead of this feature, near Pohnpei this afternoon and similar conditions are expected in the coming days as the ITCZ is expected to shift north and become more fragmented. Due to this, all forecast locations may expect a lull in the overall weather pattern after Monday, then ITCZ showers may start to rebuild starting near Majuro late week. Marine conditions look to remain benign through the weekend. Combined seas of 3 to 5 feet near Pohnpei and Kosrae and up to 6 feet near Majuro are expected over the next several days. Choppy seas and occasional gusts to 20 kt are possible across Kosrae and Majuro waters through tonight. && .Western Micronesia... Satellite observations show scattered showers across Palau and Chuuk and isolated showers across Yap. Altimetry and buoy data show combined seas between 2 to 4 feet. Overall, little change in thought from the last couple of forecasts. Guidance has backed off slightly from higher PoPs this week, but scattered showers are still expected through much of the period for Palau and Yap and less so after Monday for Chuuk. Both the GFS and ECMWF show the greatest surface convergence over Palau and Yap during the Monday night and Tuesday periods. This is when a potential increase in PoPs to high-end scattered (50%) to numerous (60-70%) may been needed with upcoming forecast cycles. For Chuuk, a lull looks to develop later this week with isolated showers outside of a trade-wind trough that looks to move in Wednesday or Wednesday night. As we head into next weekend, the pattern across western Micronesia looks to shake up as a strengthening ITCZ moves into the region. Little to no change was made with the marine forecast. Benign combined seas of 2 to 4 feet look to prevail through the forecast period. Winds are expected to remain light to gentle while variable at times. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Kleeschulte East Micronesia: Cruz West Micronesia: Williams