Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
191 FXPQ50 PGUM 281842 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 442 AM ChST Sat Jun 29 2024 .Marianas Synopsis... Satellite shows patchy showers over the region, especially near Rota, and some were locally heavy. Surface winds are gentle to moderate, and Ritidian Buoy shows combined seas mainly near 5 feet with occasional sets to 7 feet. && .Discussion... A trade-wind disturbance is crossing the Marianas this morning with scattered showers and isolated thunderstorms for today. Models are showing deeper moisture and convective support as a TUTT cell, or upper-level low, north of the Marianas drifts southwest. Also, a disturbance lifting northwest out of Eastern Micronesia looks to pass near or just south of the Marianas Sunday into Monday, with scattered showers expected again for Guam. Otherwise, generally isolated trade showers are expected for the CNMI beginning tonight and for Guam beginning Monday night. && .Marine/Surf... Gentle to moderate trade winds will continue into next week. Combined seas of 4 to 6 feet will drop to 3 to 5 feet by Monday, then back up to 4 to 6 feet by the middle of next week. A trade-wind disturbance will bring scattered showers and isolated thunderstorms today. Then, another disturbance passing to the south may bring scattered showers for Guam on Sunday through Monday. There is a moderate risk of rip currents along east facing reefs, with a low risk along all other reefs. There is a moderate risk for lightning for today, and for Guam Sunday through Monday. && .Eastern Micronesia and Chuuk... An Inter-Tropical Convergence Zone (ITCZ) pattern is gradually developing, characterized by pockets of moderate to deep convection across the region, especially in the proximity of passing trade-wind troughs. Most notable is a broad trough east of Majuro that is expected to produce numerous showers and isolated thunderstorms around Majuro today. Patchier ITCZ showers are around Pohnpei and Kosrae, with the least activity observed around Chuuk this morning. There remains a possibility for gusty winds near showers moving through Pohnpei Sunday and for Kosrae Sunday night. Otherwise, continue to expect a moderate ITCZ pattern maintaining periods of showery weather for the region through most of next week. Scatterometry shows light to gentle winds around Chuuk and light to moderate winds across eastern Micronesia. Combined seas are 3 to 5 feet for most of the region and up to 6 feet at Majuro, composed of northeast swell and small southeast swell. Fairly benign marine conditions will continue through most of next week. && .Western Micronesia for Palau and Yap... A tropical disturbance continues to drift northwest, currently near 4N130E this morning. This has induced strong convergence alongside a trough stretching northeast of the center, and produced heavy showers and thunderstorms around Palau and south of Yap overnight. As this disturbance moves towards the Philippines, the attendant trough will gradually shift to the northwest as well, however, convergent southerly winds behind the trough are still expected to maintain scattered to numerous showers and isolated thunderstorms through the weekend. Next week, a weak surface wind pattern may allow some weak disturbances to briefly appear, but we will continue to monitor subsequent model runs to see if anything significant takes shape. Scatterometry revealed gentle to moderate winds, however stronger convection persists near Palau, so included gusts reaching up to 25 kt near heavier showers today. Otherwise, winds are expected to weaken to light to gentle next week. Combined seas of 3 to 5 feet may drop a foot or two by early next week, as various swells and wind waves decrease. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Simpson Micronesia: Cruz