Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
916 FXPQ50 PGUM 200755 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 555 PM ChST Thu Jun 20 2024 .Marianas Synopsis... Gentle to moderate trade-wind pattern is bringing isolated showers and trade swell producing seas of 3 to 4 feet. && .Discussion... Seasonal trades remain in store for the region through at least the middle of next week. A minor disturbance is expected to pass just south of Guam waters Friday, but is not expected to bring higher shower coverage to the islands. && .Marine... Combined seas of 3 to 5 feet are expected through the weekend. There will be a moderate risk of rip currents along east facing reefs of the Marianas through at least Monday, while remaining low along all other reefs. && .Eastern Micronesia... Scattered showers and thunderstorms were seen south of Majuro and Pohnpei on visible satellite imagery earlier today. The Inter- Tropical Convergence Zone (ITCZ) currently located at approximately 5N175W is expected to continue to expand westward, as indicated by the deterministic GFS and ECMWF. Models show the ITCZ setting up south of Majuro, through Kosrae, and then south of Pohnpei through at least Saturday. The ITCZ is then expected to fragment toward the latter part of the weekend into independent trade-wind troughs, before dissipating early next week. A trade-wind pattern with embedded weak troughs is expected to produce isolated showers at times over Majuro, Kosrae, and Pohnpei through the middle of next week. Gentle to moderate trades and combined seas of 3 to 5 feet are expected at Kosrae and Pohnpei, with combined seas of 3 to 5 feet rising a foot this weekend at Majuro and persisting through early next week. Altimetry passes this afternoon show combined seas of 3 to 5 feet over the region, with combined seas of 4 to 6 feet seen near the International Date Line. && .Western Micronesia... A broad weak surface trough west of Chuuk State has been generating scattered showers and isolated thunderstorms along and ahead of the trough axis earlier today. The monsoon trough that stretches from the Philippines southeastward between Palau and Yap has also been generating scattered showers and isolated thunderstorms along and north of the trough axis. Daytime model guidance indicates that the monsoonal trough will lift west-northwest and weaken, as a sub- tropical ridge located northeast of Minami-Torishima continues expanding southwestward into the region through at least Saturday. After a lull in showers during the weekend, another trade-wind trough will move over Chuuk around Sunday, then continue west toward Yap and Palau, increasing shower and thunderstorm potential by early next week. Gentle trades and benign sea conditions are expected to persist through early next week at Chuuk, Yap, and Palau. Altimetry passes this afternoon show combined seas are around 3 feet across the region. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Montvila Micronesia: Kelly