FZMY50 PGUM 170027 CWFGUM Coastal Waters Forecast for the Mariana Islands National Weather Service Tiyan GU 1027 AM ChST Sat Oct 17 2026 Marianas Waters out to 40 nautical miles PMZ150-170700- 1027 AM ChST Sat Oct 17 2026 .Synopsis for Marianas Waters... A Typhoon Warning remains in effect for Guam and Rota waters, and a Tropical Storm Warning for Tinian and Saipan waters. A Typhoon Watch remains in effect for Tinian and Saipan waters. Gentle to fresh north to northeasterlies will prevail across the Marianas this evening, followed by quickly deteriorating conditions as Typhoon Champi (29W) makes its way across the Marianas tonight through Sunday evening. As such, seas are expected to quickly rise, with significant sea heights reaching as high as 35 feet during closest passage of Champi, producing dangerous seas possibly into Monday. $$ PMZ151-170700- Guam Coastal Waters- 1027 AM ChST Sat Oct 17 2026 ...TYPHOON WARNING REMAINS IN EFFECT... .TODAY...North wind 10 to 20 kt with gusts to 30 kt. Seas 5 to 7 ft. Wave Detail: East 7 ft at 9 seconds and north 4 ft at 5 seconds. Scattered locally heavy showers with isolated thunderstorms near noon. .TONIGHT...Tropical storm conditions expected. North to northeast wind 25 to 30 kt with gusts to 40 kt, becoming northwest to north tropical storm force wind to 60 kt with gusts to 80 kt. Seas 13 to 18 ft. Scattered thunderstorms. .SUNDAY...Varying typhoon force wind to 110 kt with gusts to 140 kt, deceasing to 60 kt with gusts to 80 kt during the afternoon. Seas 20 to 35 ft. Numerous locally heavy showers and scattered thunderstorms. .SUNDAY NIGHT...Southeast to south tropical storm force wind to 40 kt with gusts to 60 kt, decreasing to 30 kt with gusts to 45 kt. Seas 16 to 21 ft. Scattered showers with isolated thunderstorms. .MONDAY...Southeast wind 15 to 25 kt. Seas 10 to 13 ft. A chance of showers with a slight chance of thunderstorms. .TUESDAY...East wind 5 to 15 kt. Seas 7 to 9 ft. Wave Detail: Southwest 9 ft at 8 seconds and east 3 ft at 4 seconds. .WEDNESDAY...Northeast wind 10 kt. Seas 5 to 7 ft. Wave Detail: Northwest 7 ft at 8 seconds and northeast 2 ft at 4 seconds. $$ PMZ152-170700- Rota Coastal Waters- 1027 AM ChST Sat Oct 17 2026 ...TYPHOON WARNING REMAINS IN EFFECT... .TODAY...North wind 15 to 25 kt with gusts to 40 kt. Seas 7 to 9 ft. Wave Detail: East 7 ft at 9 seconds and north 4 ft at 6 seconds. Scattered locally heavy showers with isolated thunderstorms near noon. .TONIGHT...Southeast wind 25 kt with gusts to 40 kt, increasing to tropical storm force wind 30 to 40 kt with gusts to 60 kt. Seas 13 to 16 ft. Scattered thunderstorms. .SUNDAY...Typhoon conditions possible. East to southeast tropical storm force wind to 50 kt with gusts to 70 kt, decreasing to 30 to 35 kt with gusts to 50 kt. Seas 21 to 25 ft. Numerous locally heavy showers and scattered thunderstorms. .SUNDAY NIGHT...Southeast to south tropical storm force wind to 35 kt with gusts to 50 kt. decreasing to 20 to 25 kt with gusts to 40 kt. Seas 16 to 19 ft. Scattered thunderstorms. .MONDAY...Southeast wind 15 to 25 kt. Seas 10 to 13 ft. A chance of showers with a slight chance of thunderstorms. .TUESDAY...East wind 10 kt. Seas 7 to 9 ft. Wave Detail: Southwest 9 ft at 9 seconds and east 2 ft at 4 seconds. A chance of showers. .WEDNESDAY...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail: North 7 ft at 9 seconds and east 3 ft at 4 seconds. $$ PMZ153-154-170700- Tinian Coastal Waters-Saipan Coastal Waters- 1027 AM ChST Sat Oct 17 2026 ...TROPICAL STORM WARNING REMAINS IN EFFECT... ...TYPHOON WATCH REMAINS IN EFFECT... .TODAY...Northeast wind 15 to 25 kt with gusts to 35 kt. Seas 7 to 9 ft. Wave Detail: East 7 ft at 9 seconds and northeast 6 ft at 7 seconds. Scattered locally heavyshowers with isolated thunderstorms near noon. .TONIGHT...East to southeast wind 20 to 25 kt with gusts to 35 kt, increasing to tropical storm force wind to 35 kt with gusts to 50 kt. Seas 12 to 15 ft. Scattered locally heavy showers with isolated thunderstorms. .SUNDAY...East tropical storm force wind to 40 kt with gusts to 60 kt, decreasing to 20 to 30 kt with gusts to 40 kt. Seas 17 to 22 ft. Scattered locally heavy showers and thunderstorms. .SUNDAY NIGHT...Southeast wind 30 kt with gusts to 40 kt, decreasing to 20 to 25 kt with gusts to 35 kt. Seas 14 to 17 ft. Scattered locally heavy showers and thunderstorms. .MONDAY...Southeast wind 15 to 25 kt. Seas 10 to 13 ft. A chance of showers with a slight chance of thunderstorms. .TUESDAY...East wind 10 to 15 kt. Seas 7 to 9 ft. Wave Detail: Southwest 9 ft at 9 seconds and east 3 ft at 4 seconds. A chance of showers. .WEDNESDAY...East wind 15 kt. Seas 5 to 7 ft. Wave Detail: Northwest 7 ft at 9 seconds and east 3 ft at 5 seconds. $$