Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
524 FXPQ50 PGUM 300817 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 617 PM ChST Tue Apr 30 2024 .Marianas Synopsis... Satellite indicates scattered cumulus clouds and very isolated light showers over the Mariana Islands this afternoon. Upstream, to our east, the leading edge of a modest trade-wind surge and weak surface trough has moved to about 15N148E, and is still moving westward. Local airports report surface winds are gentle to moderate with occasional fresh gusts. Combined seas nearby are 4 to 6 feet. && .Discussion... The surface trough to our east is causing patchy clouds and isolated moderate showers. The leading edge is at about 148E, between 13N and 15N, and will arrive later tonight and likely trigger a few moderate to briefly heavy showers late tonight and early Wednesday for the local forecast zones. Otherwise, a relatively dry, gentle to moderate trade-wind flow will continue across the Mariana Islands. && .Marine/Surf... Gentle to moderate trade winds will continue this week. Combined seas of 4 to 6 feet tonight will slowly subside to 3 to 5 feet by Friday. There will be a moderate risk of rip currents along east facing reefs for the next several days, with a low risk expected along all other reefs. Surf along east facing reefs will subside a foot or two by Friday. && .Fire Weather... The KBDI is at 292 today, still in the low category. A few showers can be expected at times in the coming days, especially over the southern mountains, but wetting rains are unlikely. The KBDI will likely rise steadily and conditions will continue to dry out. && .Eastern Micronesia... Satellite analysis during the day showed trade-wind convergence south and east of the Marshalls generating scattered showers and isolated thunderstorms. Both deterministic and ensemble model members show trade-wind convergence with weak embedded troughs shifting northward and over Majuro, Kosrae, and Pohnpei generating scattered showers and isolated thunderstorms through at least this weekend. Combined seas of 4 to 6 feet are expected at Kosrae and Pohnpei through the weekend. For Majuro, combined seas of 6 to 8 feet are expected through at least Saturday before falling one to two feet. Mainly moderate trades with some gusts to fresh are expected through Thursday, then becoming gentle to moderate at Majuro, Kosrae, and Pohnpei. && .Western Micronesia... A weak surface trough moving over Chuuk State has been generating scattered showers during the day. The aforementioned weak surface trough is expected to move westward and impinge into the Near Equatorial Trough(NET) bringing chances for scattered showers and isolated thunderstorms to Palau around Thursday. Model analysis during the day shows that the NET will lift northward sometime over the next couple of days before retreating again this weekend. The northward movement of the trough and impinging weak surface troughs within the trade-wind flow will likely bring scattered showers and isolated thunderstorms to Palau and perhaps Yap Proper on Wednesday into Thursday. Afterwards, Yap Proper will be too far north of the deeper moisture and stronger convergence with only isolated showers expected through at least the weekend. Combined seas of 4 to 6 feet are expected through the weekend at Chuuk, Yap, and Palau. Gentle to moderate winds are expected at Yap and Palau through this weekend. For Chuuk, mainly moderate trades with some gusts to fresh are expected through Thursday, then weakening to gentle to moderate through the weekend. .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Simpson Micronesia: Kelly