FXPQ60 PGUM 210821

Area Forecast Discussion
National Weather Service Tiyan GU
620 PM ChST Wed Feb 21 2018

.Marianas Synopsis...
Scattered clouds with easterly trade winds prevailed across the
Marianas early this evening. Combined seas were mainly 7 to 9


Did not make many changes to the forecast. OVerall expect dry
weather to continue but with an increase in clouds by Thursday due
to the presence of a shear line to the north. Also, the ECMWF
brings some showers very close to Guam on THursday as a
disturbance passes to the south and the GFS brings some over the
Marianas. After these features move by, expect just the
possibility of light showers into the weekend and early next week.


Based on the current buoy observation at Ritidian, have extended
the High surf advisory and high rip current risk through the
night. Ritidian had been around 9 feet and is now closer to 9.5
and periods have been increasing. Current period is around 14
seconds. Guidance shows that north sell should decrease so only
left the advisory up through the morning. Depending on quickly
things come down, we will see if it needs an extension. The north
swell should continue to decrease through Thursday night and the
east swell will rise a bit into the weekend. Wind should remain 10
to 20 kt from the east or north east. Seas may rise a bit into the
weekend before decreasing early next week.


.Eastern Micronesia...
A surface trough extends southeastward from west of Chuuk down to
near EQ155E. Convergence to the east of the trough is generating some
showers and thunderstorms near Chuuk, Pohnpei, and Kosrae. Showers
will increase at Chuuk overnight before drier trades farther east
move into the area. Models show a dry trade wind pattern dominating
the area the next several days before a few more clouds and showers
develop around Sunday.


.Western Micronesia...
Dry weather is currently seen at Yap and Palau, but a trade-wind
disturbance east of Yap will bring increasing showers and
thunderstorms to Yap Thursday and Koror Thursday night. Wet, unstable
weather will persist through Friday night before tapering off. Drier
trades return over the weekend.

Models show winds increasing at Yap the next couple of days as the
disturbance nears, passing just south. This will cause both winds and
seas to become hazardous to small craft on Thursday. Conditions will
subside by Friday night. Surf will also rise and could become
hazardous, so model and observation data will need to be closely
monitored the next day or two.


GU...High Rip Current Risk until 6 PM CHST this evening for

High Surf Advisory until 6 PM CHST this evening for GUZ001>005.

Marianas Waters...None.



Nierenberg/W. Aydlett
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