Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
817 FXPQ50 PGUM 300614 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 414 PM ChST Mon Sep 30 2024 .Marianas Synopsis... Satellite observations show partly cloudy skies and isolated showers across the Marianas this afternoon. Ritidian and Tanapag buoys show combined seas between 3 and 5 feet. && .Discussion... Quiet conditions are currently present across the Marianas with isolated showers seen across the islands this afternoon. Isolated showers look to persist tonight and Tuesday before the pattern begins to change. Troughing over eastern Micronesia will begin to shift westward towards the Marianas Tuesday night bringing scattered showers and isolated thunderstorms to the region. At this time, an organized system appears unlikely, but occasional periods of locally heavy rainfall will be possible towards the latter half of this week. The GEFS and GFS suite appear to be the most aggressive with the rainfall, especially for the CNMI. The GEFS and GFS solutions would favor some numerous (60%) coverage days this week. The ECMWF has quite a bit less precipitation for the Marianas and would favor more low end scattered (30%) showers. For now the forecast blends these differences and lies in the middle with medium to high end (40 to 50%) scattered showers. && .Marine... Marine conditions are expected to remain benign through much of the period with combined seas of 3 to 5 feet through Tuesday and occasional periods of seas of 4 to 6 feet on Wednesday and Wednesday night and again on Saturday and Sunday. Winds will be gentle to moderate through at least Thursday. There will be a moderate risk for rip currents for north and east facing reefs beginning Tuesday, which should persist through Thursday as well. && .Eastern Micronesia... A weak circulation embedded within a surface trough is passing to the west of Pohnpei. A ridge in its wake is currently pushing through Kosrae and into Pohnpei with spotty showers. Another disturbance passing over Majuro is bringing numerous showers and isolated thunderstorms. This disturbance will drift west and bring an increase in showers and thunderstorms for Kosrae by late tonight and Pohnpei by later tomorrow, with showers becoming isolated for Majuro. For the rest of the period, a series of troughs will pass west through the convergence zone and will bring an uptick in showers and thunderstorms. Light to gentle winds expected to become gentle to moderate by tomorrow as the ridge weakens and the gradient increases. Winds look to become light to gentle again by late week. Seas 2 to 4 feet look to rise beginning Wednesday with the arrival of a longer period north to northeast swell, rising 1 to 2 feet. Surf will rise as well, especially along north facing reefs as a result. Seas and surf look to decrease by late week as the swell diminishes. && .Western Micronesia... Satellite shows spotty showers along trade convergence southeast of Palau and Yap Proper this afternoon. Farther east, a trough west of Pohnpei may bring some showers to Chuuk tomorrow, although models show isolated to scattered coverage, depicting the bulk of convection shifting to the north momentarily. Periods of scattered showers are expected for Chuuk in the latter half of the week with a series of trade-wind troughs moving through and strengthening trade- wind convergence at times. For Palau and Yap, a transition to more showery weather is expected overnight through Wednesday, then southerly winds may return, light and variable at times, in the latter half of the week as a SW-NE oriented trough attempts to take shape in the northwest corner of the region. Light to moderate trades and combined seas of 2 to 4 feet are expected over the next several days, increasing to 5 feet near Chuuk in the latter half of the week. North to northeast swell is around 3 ft and up to 4 feet for Chuuk starting Thursday. Minor northwest swell emanating from Typhoon Krathon reaches Palau and Yap late week. No marine or surf hazards are expected. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Williams Micronesia: Cruz/Slagle