Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
345 FXPQ50 PGUM 090837 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 637 PM ChST Sun Nov 9 2025 .Marianas Synopsis... Diffusive trades prevail across the region. Satellite imagery and Doppler radar indicate clearing skies over the horizon. Altimetry passes and buoys show seas are 5 to 7 feet. && .Discussion... After a leading edge of an extensive surface trough brings low-end scattered showers to the Marianas overnight, much more pleasant weather brought by a drier trade-wind regime is still expected for much of the week, as most of the regional convection will be limited to Micronesia south of 10N. Gentle, diffusive winds are developing, allowing moisture to drop slightly over the coming days. For most folks, this might be noticed as AC units working a little more efficiently than usual, or the late afternoon walks becoming a little more comfortable. && .Marine... Gentle to moderate trades will prevail across the Marianas for much of this week. Combined seas of 5 to 7 feet, comprised of a easterly swell, northerly swell, and westerly swell from distant Typhoon Fung-wong (32W), are expected to persist for several days while varying in strength throughout the week. A moderate risk of rip currents is expected along west, north, and east facing reefs of the Marianas for at least the next few days. Surf is expected to be elevated but remain below hazardous levels along all reeflines for much of this week. As various swells (trade swell, northerly swell, westerly swell) begin to diminish, surf may drop enough to allow the rip current risk to drop to low along east and west facing reefs before Friday. && .Eastern Micronesia... The main feature of interest is a surface trough that denotes the leading edge of increased surface convergence within the ITCZ (Inter-Tropical Convergence Zone. Currently, this feature stretches from south of Kosrae to east of Majuro. This trough will continue westward through the week, with increasing moisture values expected to develop due to moisture pooling within the ITCZ. Then, upstream troughs currently east of the Date Line move in and act as a focus for the latter half of the week. Thus, scattered showers and isolated will continue this week for Kosrae and Majuro, while developing at Pohnpei Monday, also continuing through much of this week. Seas and surf will continue to decrease slightly, as the surf has already started the downward trend. As such, seas of 4 to 6 feet can be expected this week. Moderate to gentle winds will also decrease into the light to gentle range towards mid-week, before potentially increasing slightly by the weekend. && .Western Micronesia... Satellite imagery shows isolated showers across Palau and Yap this evening with a mid-level cloud deck starting move over Yap but still east of Palau. Further east, a weak trough is passing through western Chuuk State, while Chuuk Lagoon is experiencing partly cloudy skies and isolated showers. However, just to the east of Chuuk, scattered showers and isolated thunderstorms is developing along the northern edge of a weak trough moving along the equator. This area of convection is expected Chuuk Lagoon by midnight and likely continuing into Monday as the trough passes south of Chuuk. ASCAT and 925-850 mb streamline analysis suggest a minor ridge- like pattern in western Micronesia in the wake of TY Fung wong. This pattern will help to keep showers isolated and weaken winds at Palau and Yap, with winds becoming variable at times before shifting towards the northeast as the trade- wind flow returns. Light winds may trigger some island-effect convection at Palau during the peak heating hours of Monday, but given the ridge-like pattern kept, showers isolated but left the potential for isolated thunderstorms at Palau. Over the next few days, model guidance suggest a broad and weak circulation will develop in the region and progress westward, likely developing within the trough currently passing just north of the equator just south-southeast of Chuuk this evening. Models currently favor the circulation passing south of the main islands, with convergent flow north of the circulation will help to support at least scattered shower and isolated thunderstorms across Palau, Yap, Chuuk by the middle of the week. If the circulation shifts northward slightly then numerous showers will be possible at times at Palau and Chuuk. As the circulation shifts westward, an overall wet patter will continue at Palau and Yap through the week, while Chuuk may see periods of drier weather around Thursday before a passing trade-wind trough increases the potential for showers once again around Friday. Altimetry data suggest seas are around 6 to 8 feet around Palau and Yap and 6 to 7 feet around Chuuk. Palau and Yap are still experience an elevated west swell, but slowly weakening westerly swell from distant TY Fung-wong so the High Surf Advisory for surf around 7 to 10 feet along north and west facing reefs and minor coastal inundation is still valid through Monday afternoon. The west swell is expected to become more northwest and decrease enough to allow high surf and the risk of coastal inundation to end by Monday night. For Chuuk, the tide prediction shows the high tide peaked Friday and Saturday and has started to decrease and will continue to decrease, marking the end of this King Tide cycle. The risk of coastal flooding during high tide is subsiding for vulnerable shorelines, so the Coastal Flood Statement was allowed to expire. A elevated north to northeast swell will move through the region by the middle of the week, but surf is not expected to rise above hazardous levels of 9 feet along north facing reefs at this time. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Montvila East Micronesia: Doll West Micronesia: Schank