991
FZMY50 PGUM 121628
CWFGUM

Coastal Waters Forecast for the Mariana Islands
National Weather Service Tiyan GU
228 AM ChST Thu Mar 13 2025

UPDATED FOR SMALL CRAFT ADVISORY FOR TINIAN AND SAIPAN

Marianas Waters out to 40 nautical miles

PMZ150-122000-
228 AM ChST Thu Mar 13 2025

.Synopsis for Marianas Waters...
An elevated northerly swell, in combination with northeast trade
swell and shear line-driven wind waves, has brought near-hazardous
7 to 9 foot seas near Tinian and Saipan, and 6 to 8 foot seas
near Guam and Rota. These seas may increase another foot or two
Thursday night into Friday as a large, long-period north swell
enters the region. Much of the energy associated with this swell
will be focused east of the islands as the swell just grazes the
Marianas, but seas may become hazardous at times by the end of the
week as combined sea heights approach 10 feet. The effects of the
incoming long-period swell will mainly be felt over north and
east portions of Saipan, Tinian, and Rota coastal waters, most
likely from late Thursday night through Friday. Tinian and Saipan
will see scattered showers overnight as the shear line lingers
nearby over the northern CNMI.

$$

PMZ151-152-122000-
Guam Coastal Waters-Rota Coastal Waters-
228 AM ChST Thu Mar 13 2025

.TONIGHT...East wind 15 kt. Seas 6 to 8 ft. Wave Detail:
Northeast 6 ft at 9 seconds, north 4 ft at 11 seconds and east 3
ft at 5 seconds.
.THURSDAY...East wind 15 kt. Seas 7 to 9 ft. Wave Detail:
Northeast 7 ft at 10 seconds and east 3 ft at 5 seconds.
.THURSDAY NIGHT...East wind 15 kt. Seas 7 to 9 ft. Wave Detail:
Northeast 8 ft at 11 seconds and east 3 ft at 6 seconds.
.FRIDAY...East wind 15 to 20 kt. Seas 8 to 10 ft. Wave Detail:
Northeast 7 ft at 11 seconds, east 4 ft at 6 seconds and north
4 ft at 15 seconds.
.FRIDAY NIGHT...East wind 15 to 20 kt. Seas 7 to 9 ft. Wave
Detail: Northeast 7 ft at 11 seconds, east 4 ft at 6 seconds and
north 4 ft at 15 seconds.
.SATURDAY...East wind 15 kt. Seas 7 to 9 ft. Wave Detail:
Northeast 7 ft at 10 seconds, north 4 ft at 14 seconds and east
3 ft at 5 seconds.
.SUNDAY...East wind 15 kt. Seas 6 to 8 ft. Wave Detail: East 7 ft
at 9 seconds, east 3 ft at 5 seconds and northeast 3 ft at
13 seconds.
.MONDAY...East wind 10 to 15 kt. Seas 5 to 7 ft. Wave Detail:
East 6 ft at 9 seconds, east 3 ft at 4 seconds and northeast 2 ft
at 12 seconds.

$$

PMZ153-154-122000-
Tinian Coastal Waters-Saipan Coastal Waters-
228 AM ChST Thu Mar 13 2025

...SMALL CRAFT ADVISORY IN EFFECT THROUGH EARLY SATURDAY
MORNING...

.REST OF TONIGHT...East wind 15 to 20 kt. Seas 7 to 9 ft. Wave
Detail: Northeast 8 ft at 11 seconds, east 4 ft at 5 seconds and
north 4 ft at 11 seconds. Scattered showers.
.THURSDAY...East wind 15 to 20 kt. Seas 8 to 10 ft. Wave Detail:
Northeast 9 ft at 10 seconds and east 4 ft at 6 seconds.
.THURSDAY NIGHT...East wind 15 to 20 kt. Seas 8 to 10 ft. Wave
Detail: Northeast 9 ft at 12 seconds and east 3 ft at 6 seconds.
.FRIDAY...East wind 15 to 20 kt. Seas 8 to 10 ft. Wave Detail:
Northeast 9 ft at 11 seconds, east 4 ft at 6 seconds and north
4 ft at 15 seconds.
.FRIDAY NIGHT...East wind 15 to 20 kt. Seas 8 to 10 ft. Wave
Detail: Northeast 8 ft at 10 seconds, east 4 ft at 6 seconds and
north 4 ft at 15 seconds.
.SATURDAY...East wind 15 to 20 kt. Seas 7 to 9 ft. Wave Detail:
Northeast 7 ft at 10 seconds, north 4 ft at 14 seconds and east
3 ft at 5 seconds.
.SUNDAY...East wind 15 kt. Seas 6 to 8 ft. Wave Detail: East 7 ft
at 9 seconds, east 3 ft at 5 seconds and northeast 3 ft at
13 seconds.
.MONDAY...East wind 15 kt. Seas 5 to 7 ft. Wave Detail: East 6 ft
at 9 seconds, east 3 ft at 4 seconds and northeast 2 ft at
12 seconds.

$$