Area Forecast Discussion
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FXPQ60 PGUM 112029

Area Forecast Discussion
National Weather Service Tiyan GU
625 AM ChST Tue Dec 12 2017

.Marianas Synopsis...East trade-winds and isolated showers prevail
across the Marianas this morning.


Little change made to the forecast. Did update winds with new model
data. Latest model data continue to show decreasing deep layer
moisture through the day. Latest Water Vapor imagery hints at
decreasing deep layer moisture inching in from the east validating
the model projections. With drier air filtering expect only partly
cloudy skies with isolated showers today. Models show that the dry
air will persist over the area keeping the showers at a minimum
through Wednesday night.

An area of trade-wind convergence and recovering deep layer moisture
will generate isolated showers and thunderstorms Thursday through


Ipan, Tanapag and Ritidian buoys show sea heights around 5 to 7 feet.
Satellite altimetry data shows 6 foot seas over the local area. All
three buoys show an east to northeast swell. Ritidian and Tanapag
buoys show a northwest swell. Model data does show both swells over
the area through the forecast. The east swell will be high enough to
generate a high rip current risk on east facing reefs through at
least Wednesday afternoon while the north swell will produce a
moderate rip current risk on north facing reefs through tonight.


.Eastern Micronesia and Chuuk...
IR satellite shows two distinct areas of showers and thunderstorms
this morning. The first is across Chuuk and Pohnpei to near
Kosrae, and the second is east and southeast of Majuro. Showers
near Chuuk and Pohnpei are associated with a surge of fresh to
strong trades converging along the northeast edge of a near-
equatorial trough and weak circulation southwest of Pohnpei. This
will remain nearly- stationary the next few days before eventually
heading WNW. The convergence zone near Majuro will spread
westward, prolonging showery weather across the region a couple
more days. Expect a drier pattern to develop across the region by
the weekend.

Large trade-wind swell and wind waves will maintain hazardous surf
on Kosrae for several more days. Trade-wind swell and wind waves
have subsided enough at Majuro to allow surf to fall below hazardous
levels, therefore the High Surf Advisory is no longer in effect
there. Winds have subsided near Majuro and are no longer hazardous
to small craft, but seas will remain elevated. GFS shows fresh to
strong trades returning to Majuro by midweek.


.Western Micronesia...
The circulation just west of Koror near 8N130E (96W) and the monsoon
trough extending east-southeastward from it remain near Koror and
just south of Yap. IR satellite animation shows only a few
showers near Yap and Koror with most convection just west of Koror
and northwest of Yap. Showers are expected to gradually increase
over the area the next couple of days as models indicate the
circulation will be very slow-moving as it becomes better
organized. This will prolong the duration of southwest to west
monsoon flow in the region. Should this circulation develop faster
before it pulls away from the area, combined sea forecasts will
likely need to be increased.

GU...High Rip Current Risk through Wednesday afternoon for GUZ001>004.

Marianas Waters...None.


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