Area Forecast Discussion
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FXPQ60 PGUM 192105

Area Forecast Discussion
National Weather Service Tiyan GU
703 AM ChST Tue Feb 20 2018

.Marianas Synopsis...East trade-winds, a few clouds and showers
prevail across the Marianas this morning.


.Discussion...A few changes made to the forecast, one was to update
winds with new model data and the second was to trim some clouds
from today`s forecast. Satellite imagery from this morning did
show clouds with a shear line near Saipan. The imagery also showed
that the clouds have thinned out. Models still show clouds
increasing through the morning so expect mostly cloudy skies this
afternoon and persisting through the night. Drier air filtering
into the area will bring back partly cloudy skies Wednesday.
Trade-wind convergence will produce a return to mostly cloudy
skies Thursday, which will continue through Thursday night. Deep
layer moisture will be lacking so showers will remain isolated
through the week.


Tanapag, Ritidian and Ipan buoys show sea heights of between 6 to
7 feet. Ritidian and Ipan buoys show an east swell. The east swell
will persist through the forecast. Ritidian and Tanapag show a
north which should remain through Saturday. Expect seas of 6 to
8 feet through Wednesday.

Expect winds of 10 to 20 knots through the week. A slightly higher
pressure gradient may cause slightly winds Wednesday through
Friday. A few models suggest that winds may become gusty on those
days. These gusts may be persistent enough to require that a
Small Craft Advisory be issued at that time.

Models show sea heights decreasing down to 5 to 7 feet by Friday. At
this time the swells should not cause a high rip current risk.


.Eastern Micronesia and Chuuk...
A weak trade-wind disturbance continues to generate spotty
convection near Chuuk, Pohnpei and Kosrae. More showers and
thunderstorms are found south of these locations. This disturbance
will continue west with unsettled conditions continuing at these
locations a couple more days. A trade wind surge over the Marshall
Islands is causing showers and thunderstorms near and just south
of Majuro. Drier air is moving in from the northeast pushing the
showers and thunderstorms southwest toward Kosrae. Generally drier
weather and fresh to strong trades are expected through the end
of the week across the region.

Trade-wind swell and wind waves will build across the region tonight
and Wednesday. A long-period northwest swell generated by strong
winds east of Japan will also build across the region Wednesday.
Seas and surf will rise and could become hazardous late in the week
at Chuuk, Pohnpei, Kosrae and Majuro.


.Western Micronesia for Yap and Koror...
A dry weather pattern will persist at Yap and Koror thru
Wednesday. A broad trade-wind disturbance currently near Pohnpei
and Chuuk will bring stronger winds and a better chance of showers
and thunderstorms to Yap and Koror late Wednesday night and

Trade-wind swell and wind waves will build by Thursday in response
to stronger winds over the area. This could generate hazardous
surf and conditions hazardous for small craft near Koror and Yap


Marianas Waters...None.


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