995
FZMY50 PGUM 302339
CWFGUM

Coastal Waters Forecast for the Mariana Islands
National Weather Service Tiyan GU
939 AM ChST Thu Oct 1 2026

Marianas Waters out to 40 nautical miles

PMZ150-010845-
939 AM ChST Thu Oct 1 2026

.Synopsis for Marianas Waters...
Moderate to fresh westerlies will shift to the southwest and
strengthen to strong to gale tonight. Combined seas of 7 to 9 ft
tonight will rapidly increase to 10 to 12 ft tonight as Tropical
Storm (TS) Choi-wan (26W) approaches the northern CNMI and brings
an elevated southwesterly monsoon swell to the Marianas. For
Saipan and Tinian, a Tropical Storm Warning is now in effect. For
Guam and Rota, frequent gale-force gusts could lead to a Gale
Warning. A Gale Watch has been issued for Guam and Rota for the
potential for frequent gale gusts. Mariners should continue
monitoring the forecast for changes in the coming days.

$$

PMZ151-152-010845-
Guam Coastal Waters-Rota Coastal Waters-
939 AM ChST Thu Oct 1 2026

...SMALL CRAFT ADVISORY IN EFFECT FROM LATE THIS AFTERNOON
THROUGH EARLY FRIDAY MORNING...
...GALE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY
AFTERNOON...

.TODAY...West wind 15 to 20 kt. Seas 7 to 9 ft. Wave Detail:
Southwest 7 ft at 8 seconds, west 4 ft at 5 seconds and north 3 ft
at 10 seconds. Scattered showers with isolated thunderstorms.
.TONIGHT...West wind 20 to 25 kt with frequent gusts to 35 kt
possible. Seas 9 to 11 ft. Wave Detail: Southwest 7 ft at 8
seconds, west 6 ft at 7 seconds and north 4 ft at 11 seconds.
Numerous showers with isolated thunderstorms.
.FRIDAY THROUGH SATURDAY...Southwest wind 30 kt with frequent gusts
to 40 kt possible. Seas 12 to 15 ft. Numerous showers with
isolated thunderstorms.
.SUNDAY...Southwest wind 20 to 30 kt. Seas 10 to 13 ft. Wave
Detail: West 9 ft at 9 seconds, southwest 8 ft at 9 seconds and
northwest 4 ft at 13 seconds. A chance of showers with a slight
chance of thunderstorms.
.MONDAY...Southwest wind 20 to 25 kt. Seas 8 to 10 ft. Wave
Detail: Southwest 8 ft at 8 seconds, west 5 ft at 9 seconds and
northwest 3 ft at 13 seconds. A chance of showers with a slight
chance of thunderstorms.

$$

PMZ153-154-010845-
Tinian Coastal Waters-Saipan Coastal Waters-
939 AM ChST Thu Oct 1 2026

...TROPICAL STORM WARNING IN EFFECT...

.TODAY...Northwest wind 15 to 25 kt. Seas around 8 ft. Wave
Detail: Southwest 7 ft at 8 seconds, northwest 4 ft at 6 seconds
and north 3 ft at 10 seconds. Numerous showers with isolated
thunderstorms.
.TONIGHT...West tropical storm force wind to 35 kt expected with
gusts to 50 kt. Seas around 10 ft. Numerous showers with isolated
thunderstorms.
.FRIDAY...West tropical storm force wind to 35 kt with gusts to
50 kt expected. Seas 13 to 15 ft. Numerous showers with isolated
thunderstorms.
.FRIDAY NIGHT...Southwest tropical storm force wind to 35 kt with
gusts to 55 kt expected. Seas 14 to 16 ft. Widespread locally
heavy showers with isolated thunderstorms.
.SATURDAY...West wind 30 kt. Seas 12 to 15 ft. Numerous showers
with isolated thunderstorms.
.SUNDAY...Southwest wind 30 kt. Seas 10 to 13 ft. Wave Detail:
West 9 ft at 9 seconds, west 8 ft at 9 seconds and northwest 4 ft
at 13 seconds. Numerous showers with a slight chance of
thunderstorms.
.MONDAY...Southwest wind 20 to 30 kt. Seas 8 to 9 ft. Wave
Detail: Southwest 8 ft at 9 seconds, west 4 ft at 9 seconds and
northwest 3 ft at 13 seconds. A chance of showers with a slight
chance of thunderstorms.

$$