FXPQ50 PGUM 150824 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 624 PM ChST Wed Apr 15 2026 .Marianas Synopsis... Latest visible satellite shows Typhoon Sinlaku to the northwest of Tinian and Saipan, moving slowly north-northwest into the northern CNMI. Cloudy skies with numerous to widespread heavy showers are found over Rota, Tinian and Saipan, while Guam is seeing only isolated showers under cloudy skies. Altimetry shows seas ranging from 16 to 20 feet for Guam, increasing to 35 feet for Tinian and Saipan. && .Discussion... TY Sinlaku continues to slowly move north-northwest, away from Tinian and Saipan. Winds are subsiding over Guam and may fall below tropical storm force this evening, Thursday morning for Rota and Thursday evening for Tinian and Saipan. It is important to remember that even though the winds are subsiding, stronger gusts are possible over the next few days, especially with any showers that do occur. Although skies remain cloudy across Guam, showers have decreased to isolated and the remainder of the week into next week looks to remain dry. For Rota, a few bands of heavy showers are still likely, though showers also look to become isolated at Rota Thursday. Tinian and Saipan will continue to see widespread heavy showers and isolated thunderstorms through tonight, decreasing to isolated Friday. For the weekend into next week, a dry pattern will remain over the islands. && .Marine... Dangerous seas and winds continue across the region this evening. Northern Guam waters can expect tropical storm conditions for the next several hours as TY Sinlaku moves farther north. TS conditions could continue for Rota waters through Thursday afternoon and for Tinian and Saipan through late Thursday night or early Friday morning. Seas will be slow to subside, with hazardous seas likely through at least Thursday night for Guam and Rota; and through Friday for Tinian and Saipan. Strongest winds and highest seas will be over the northern portions of the waters. The swell produced by TY Sinlaku will maintain dangerous surf and significant coastal flooding over the next couple of days, with Coastal Flood Warnings likely to be replaced by Coastal Flood Advisories into the weekend, along with High Surf Warnings being replaced with High Surf Advisories. Seas could remain above 10 feet into the weekend as well. && .Hydrology... The rainfall potential continues to decrease, though heavy rains are still possible for Tinian and Saipan through tonight and for Rota through this evening. By Thursday evening, heavy rainfall is no longer expected as TY Sinlaku continues to move away from the Marianas. && .Tropical Systems... At 500 PM ChST, 0700 UTC, the center of Typhoon Sinlaku was located near 16.0N 144.8E, roughly 90 miles northwest of Tinian and Saipan, and 175 miles north of Guam. TY Sinlaku remains a powerful, well- organized Category 3 storm, spanning roughly 500 miles across, with the outer rain bands extending up to 700 miles outward from the center, passing southeast of Iwo To and extending over Minamitorishima. However, Sinlaku is showing signs of weakening, with satellite imagery depicting a broader, more weakly-defined eye and diminished convection within the eyewall. Sinlaku has been moving very slowly away to the north-northwest this afternoon, at around 3 to 4 mph, becoming nearly stationary at times as typhoon-force winds continue across Tinian and Saipan. An Extreme Wind Warning, issued for devastating sustained winds of 115 mph or greater, was extended for Tinian and Saipan through the morning hours as the east to southeastern edge of the eyewall lingered overhead, finally exiting northwest of the islands around mid-day. Maximum sustained winds remain at 125 mph, and Sinlaku is forecast to continue weakening through the next few days as it moves through the northern CNMI. A Typhoon Warning continues for Tinian, Saipan, Rota, Alamagan, Pagan, and Agrihan, while a Tropical Storm Warning and Typhoon Watch remain in effect for Guam. && .Eastern Micronesia... An unsettled pattern has set up from RMI to central eastern Micronesia. This is due to the remains of a fragment of the Inter-Tropical Convergence Zone (ITCZ) interacting with a trade-wind trough traversing the ITCZ. As Sinlaku moves further away. This will allow for the ITCZ fragment to move westward over the coming days and bring showers to Kosrae and lingering in RMI. These showers may move into Pohnpei around Friday night and Monday. Altimetry shows combined seas of 6 to 8 feet near Pohnpei and 4 to 6 near Majuro. Winds are expected to gentle to moderate falling to light to gentle by the beginning of next week. && .Western Micronesia... Scatterometry data shows gentle to fresh westerlies across the region. Satellite imagery shows overall patchy showers within this pattern, across Palau, Yap, and Chuuk. Altimetry shows seas slightly higher than wave model guidance near Chuuk, with seas increasing to 12 to 15 feet in far northwestern Chuuk State. Northwest swell emanating from Typhoon Sinlaku and swell produced by persistent westerlies is expected to produce hazardous surf along west and north facing reefs of Chuuk through Thursday afternoon. For Yap and Palau, large northeast swell emanating from distant Typhoon Sinlaku continues to produce hazardous seas within Yap coastal waters and could peak around 11 to 13 feet before slowly tapering off on Thursday. A Small Craft Advisory remains in effect for Yap through Thursday afternoon. Continue to expect elevated seas within Palau coastal waters, but seas reaching hazardous criteria of 10 feet is only expected through tonight, so the Small Craft Advisory was shortened, to expire early Thursday morning. This long-period swell is also expected to produce hazardous surf along north and east facing reefs of Yap. Hazardous surf, combined with the higher high tides with the new moon cycle, minor coastal inundation will be possible along northern and eastern shorelines at times of high tide over the next few days. Hazardous surf is also expected along north facing reefs of Palau , but coastal inundation is mainly a concern for Yap, when hazardous surf nears dangerous levels of 15 feet. High Surf Advisories remain in effect for Yap and Palau and a Coastal Flood Statement remains in effect for Yap through Friday afternoon. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...Coastal Flood Warning until 5 AM ChST Thursday for GUZ001. Flood Watch through late tonight for GUZ001. High Surf Warning until 5 PM ChST Friday for GUZ001. Tropical Storm Warning for GUZ001. Typhoon Watch for GUZ001. MP...Flood Watch through late tonight for MPZ001>003. High Surf Warning until 5 PM ChST Friday for MPZ001>003. Coastal Flood Warning until 5 PM ChST Thursday for MPZ001. Typhoon Warning for MPZ001>003. Coastal Flood Warning until noon ChST Friday for MPZ002-003. Marianas Waters...Tropical Storm Warning for PMZ151. Typhoon Watch for PMZ151. Typhoon Warning for PMZ152>154. && $$ Marianas: Kleeschulte East Micronesia: Bowsher West Micronesia: Cruz Tropical: DeCou