FXPQ50 PGUM 221003 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 803 PM ChST Sat Aug 22 2026 .Marianas Synopsis... Typhoon Saudel is currently moving over Agrihan, and another tropical disturbance continues to strengthen northwest of Yap. This will maintain the persistent southwest monsoon flow over the next few days. && .Discussion... Typhoon Saudel is currently moving over Agrihan, and will pass through the Mariana chain over the next few hours. However, Invest 97W northwest of Yap is strengthening. This will prolong and intensify the persistent southwest monsoon, with locally heavy rainfall developing from Guam northward to Rota over the next 72 hours. This will allow the southwest monsoon flow to actually strengthen, especially Sunday through Monday night for Guam and the south central CNMI. MIMIC water vapor imagery shows the higher precipitable water values moving north across Guam and it's coastal waters, with the previously drier air from Rota to Saipan moistening. This may allow heavier rainfall to develop, even if showers are more scattered in coverage tonight and Sunday. With this in mind, the new forecast package attempts to convey this, along for increasing potential area-wide Sunday night into Tuesday. && .Marine... Fresh to locally strong southwest winds will continue across the coastal waters with combined seas around 7 to 10 feet expected through the rest of the weekend. A Small Craft Advisory is now in effect for all zones through Sunday afternoon. The High Risk of Rip Currents and High Surf Advisory was dropped from the east-facing reefs this afternoon, but north and west-facing reefs were added as swells from Typhoon Saudel and developing Invest 97W build throughout the waters. Hazardous surf along these reefs and dangerous rip currents can be expected through at least Sunday afternoon. Othwerise, scattered showers and isolated thunderstorms expected through midweek, with locally heavy showers possible. && .Tropical Systems... As of 700 PM ChST, 0900 UTC, the center of Typhoon Saudel (17W) was located near 19N145E just northwest of Agrihan. The System continues to move northwest, now slowing its forward speed to 10 mph. The maximum sustained winds have increased, now to 110 mph near the center. Saudel will continue on this trajectory to then slowly shift to the west-northwest, accelerating once again through Sunday and further intensify as it continues to move away from the Marianas. A tropical disturbance, known as JTWC's Invest 97W, is currently centered near 11N136E northwest of Yap and well north-northeast of Palau. The system is labeled as a Medium, which means that development into a significant tropical cyclone is likely, but not within the next 24 hours. Most of the convection associated with this feature is concentrated within the western flanks interacting and enhancing a monsoon surge, that will continue to produce inclement weather across Palau tonight. The system is expected to continue moving away to the north and then to the northeast, following a favorable environment while pivoting toward departing TY Saudel well to the northeast, with some resemblance of a distant Fujiwara Effect. This is expected to help further prime the environment around the Marianas for another tropical disturbance to potentially develop in the area, bringing in another period of heavy rainfall to the region next week (more details in the Hydrology Section). && .Hydrology... Model guidance suggests that another tropical disturbance is becoming more likely to develop in the area next week, in the wake of TY Saudel's exit from the region, followed by decreasing wind shear assisted by the extensive monsoon trough and aforementioned 97W's movement nearby. This disturbance is forecast to bring heavy rainfall to the Marianas with ensemble guidance suggesting rainfall totals of 4 to 7 inches possible. Periods of heavy rainfall will help to saturate soils and increase mudslide potential during mid to late week. Residents on the Marianas need to closely monitor this developing situation as flood watches, advisories, and flash flood warnings may be issued later. && .Eastern Micronesia... A broad tropical disturbance to the east of Majuro and a large northwesterly inflow into the system continue to bring unsettled weather to Majuro and are building into Kosrae and Pohnpei tonight and tomorrow night respectively. Numerous locally heavy showers and isolated thunderstorms may become widespread tonight for Majuro. Precipitation looks to remain elevated until the system drifts northwest out of the area sometime Monday. Winds will also be elevated and potentially peaking at 25 kts. This will lead to elevated sea heights that are expected to remain below hazardous levels at this time. By Monday, conditions will likely dry out temporarily. For Kosrae, the monsoonal inflow will increase shower coverage for Sunday and Monday with gusty winds possible in any thunderstorms. Pohnpei is also expected to see increased shower coverage but to a slightly lesser extent, with locally heavy rainfall still possible. These showers and isolated thunderstorms may lessen by Tuesday as the monsoonal flow slowly drifts back northward. Combined seas are currently 5 to 6 feet across all the islands and will remain fairly steady except for Majuro which may experience up to 6 to 8 foot seas sometime on Monday. && .Western Micronesia... As the aforementioned 97W continues moving away from the region to the north-northwest, it will drag the enhanced southwesterly monsoonal flow along with it, allowing conditions to improve significantly across Palau and Yap. As such, the monsoon surge from days prior is no longer expected to produce significant rainfall and sustained fresh to strong westerlies across Yap, but likely to continue bringing strong to near-gale westerlies to Palau in the first few hours tonight before tapering down thereafter. Preliminary estimates indicate more than 18 inches of rain has fallen at Yap during this rain event, with much less over Palau. As Typhoon Saudel (17W) and Invest 97W continue to drag the aforementioned monsoonal flow and associated moisture northward, this will introduce slightly diffusive flow to Palau that may bring periods of dry spells the next several days. Mid to long-term guidance indicates a reigniting monsoon surge across eastern Yap State and potentially the Marianas before the middle of next week, so residents of Yap should continue to monitor this development as we head into next week. While moist westerlies are expected to continue at Chuuk for most of the forecast period, a tropical ridge is expected to anchor itself just north of the Equator, allowing Chuuk to fall in between the convectively active pattern hugging 10N and the ridge to the south. This will allow patchy showers and some thunderstorms to form at Chuuk for much of the forecast period, followed by a dry spell in the second half of next week as a larger buffer circulation induces more diffusive flow. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...High Rip Current Risk through Sunday afternoon for GUZ001. High Surf Advisory until 4 PM ChST Sunday for GUZ001. MP...High Rip Current Risk through Sunday afternoon for MPZ001>003. High Surf Advisory until 4 PM ChST Sunday for MPZ002-003. Marianas Waters...Small Craft Advisory until 5 PM ChST Sunday for PMZ153-154. && $$ Marianas: Doll/Whisnant East Micronesia: Ogle West Micronesia/Tropical/Marianas: Montvila Hydrology: Whisnant