Area Forecast Discussion
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FXPQ60 PGUM 180807

Area Forecast Discussion
National Weather Service Tiyan GU
606 PM ChST Fri Aug 18 2017

.Marianas Synopsis...Southeast winds and isolated showers and
thunderstorms prevail over the Marianas this morning.


Afternoon scatterometer data showed a circulation near 8N145E. A
surface trough extends from the circulation northward to just east of
the Marianas. This trough will progress westward and across the local
area through Saturday before washing out. Satellite and lightning
data indicated scattered showers and isolated thunderstorms around
the area during the afternoon with decreasing activity by late
afternoon. Models show the return of the showers with scattered
showers and isolated thunderstorms prevailing before midnight.
Deep-layer moisture and low-level wind flow convergence will allow
the scattered showers and isolated thunderstorms to persist through
Saturday.   Lingering moisture and a approaching upper-level low
will keep skies mostly cloudy and produce isolated showers and
thunderstorms Saturday night and Sunday.


Observations this afternoon from Ritidian, Tanapag, and Ipan buoys
indicate combined sea heights of 2 to 3 feet. Expect seas of 2 to 3
feet the next few days.

An east swell will be present through the forecast. Surf will be 3 to
5 feet on east facing reefs and 2 to 4 feet on north facing reefs.
Surf on west and south will be 3 feet at best. Little will change
through the weekend and the rip current risk will remain low.


.Eastern Micronesia...
Conditions remain fairly quiet across the area except for isolated
showers and thunderstorms across Pohnpei State. Elsewhere, a few
showers and thunderstorms are seen along a near-equatorial trough
that sits just south of Pohnpei, Kosrae and Majuro. Showers will
fill in along the trough at Kosrae tonight and at Majuro on Saturday.
This trough will slowly lift north of all 3 locations over the
weekend causing winds to weaken and shift to the south or become
briefly variable.


.Western Micronesia...
Showers and thunderstorms prevail across much of the region with
moist monsoon flow over Yap and Koror and a convergent trade wind
pattern at Chuuk. Models show a broad circulation developing well
NW of Yap and Palau the next several days. This will maintain
a SW to south wind across the area through the weekend before a
weak ridge pushes into the area ahead of a surface trough near
Chuuk. Weather will be unsettled with isolated thunderstorms for
much of the next several days with showers becoming scattered at
times. At Chuuk, scattered showers and isolated thunderstorms will
linger through tonight before the trough moves farther west.


Marianas Waters...None.


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