Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
606 FXPQ50 PGUM 241953 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 553 AM ChST Sat Jul 25 2026 .Marianas Update... Satellite and radar show partly cloudy skies and isolated showers this morning. Winds are expected to be pretty light today, so we may kick up some island effect showers, especially on Guam. Combined seas will be 3 to 4 feet. The rip current risk and the fire danger will be low, and little or no thunderstorm activity is expected, so it should be a good weekend to get out and enjoy the outdoors a little, just bring some sunscreen. && .Fire weather... Looks like in a day or two we`re going to have the lamest fire weather season ever, with at least half the year done already, and mostly the off season ahead of us. If you`re going to have a boring year at least you can set some records doing it. Let`s see just how boring fire season can get around here. && .Eastern Micronesia Update... Wind speeds looked like they might be just a bit high, so knocked them down by 5 knots. Otherwise, everything was in fine shape, with a fairly wet day on tap for Eastern Micronesia. A near-equatorial or almost a monsoon trough will maintain scattered showers out here for most of the forecast period. && .Western Micronesia Update... West Micronesia, conversely, has dried out a little. So I lowered the PoP`s at Chuuk from 50 to 30 for today, as only mid-level clouds are over them, and not all that many of those. The winds at both Yap and Chuuk might have been just a bit too strong, so just shaved 5 knots off the wind speeds at each. Koror Palau has a dry slot that built in for the mid-level cloudiness that has been over them, so their rather dry forecast looked good for today. && .Prev discussion... /issued 548 PM ChST Fri Jul 24 2026/ Marianas Synopsis... Light to gentle easterlies prevail across the Marianas. Satellite imagery and Doppler radar indicate slow-moving showers and thunderstorms across Rota, Tinian and Saipan waters. Buoys show seas are just below 4 feet. Discussion... The proximity to the monsoon trough will continue to produce regional instability, allowing scattered showers and isolated thunderstorms to continue into the evening. Showers and thunder will taper down coming into Saturday morning, with island showers returning near noon as winds remain light and variable. Invest 93W, now a sub-low and located over the northern Marshalls, is expected to continue on its journey toward the Marianas and eventually break down into an open trough, with some chance to bring just low-end scattered showers to the area in the first half of next week. Marine... Combined seas of 3 to 4 feet are expected for much of the forecast period, as various swells from the west and east remain weak. Due to these weak swells, a low risk of rip currents is expected along all reefs of the Marianas for at least the next several days. Eastern Micronesia... The main weather theme will be a continued unsettled pattern continuing as we head through the weekend and into next week. In general, a monsoon trough bisects the area, stretching from Pohnpei to south of Majuro, connecting to a broad/weak circulation near 7N177E, before crossing the Date Line near 8N180. The circulation east of Majuro, and another one further east near 9N170W, looks to continue west over the next several days. While this occurs, a persistent west-southwest monsoon flow will continue. This allows the trough to act as a good convergence boundary, allowing scattered showers and isolated thunderstorms to develop. The previous forecasts had this well in hand and we continued that theme this afternoon, nudging rainfall probabilities up, just slightly. Winds will generally be light to gentle at Kosrae and Majuro, with general to moderate winds at Pohnpei decreasing back into the light to gentle range over the weekend. Seas of 3 to 5 feet will also persist through the forecast period. Western Micronesia... Wet weather will continue at Chuuk and Yap as surface convergence in the vicinity of the monsoon trough brings periods of scattered to low-end numerous showers and isolated thunderstorms to both locations through the weekend. Drier weather is expected at Palau through Saturday with shower chances increasing starting Sunday. Light to moderate west to northwest winds will continue through the weekend at Palau and Yap with the strongest winds being at Yap through Saturday. West to southwest gentle to moderate winds will continue at Chuuk through Sunday. Generally benign marine conditions will persist through the weekend at all forecast points with combined seas hovering around 3 to 4 feet. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas/East and West Micronesia Update: Stanko Marianas: Montvila East Micronesia: Doll West Micronesia: Whisnant