Area Forecast Discussion
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FXPQ60 PGUM 300734

Area Forecast Discussion
National Weather Service Tiyan GU
532 PM ChST Sun Apr 30 2017

.Marianas Synopsis... East trade-winds and a few small showers
prevail over the Marianas this afternoon.


Afternoon satellite imagery showed just a few clouds over the
Marianas. Only a few tweaks made to forecast. GFS20 and ECMWF hint at
a brief period of mostly cloudy skies after midnight through the
early morning hours. This appears to be from weak trade-wind
convergence as the ridge over the Marianas gives way to slightly
stronger winds. Satellite imagery does show some clouds east of the
islands and these will move west during the night.

Models keep deep layer moisture to a minimum through much of the
forecast with a few periods of patchy clouds and showers but showers
coverage will remain isolated at best.


Observations this afternoon from Ritidian, Tanapag, and Ipan buoys
indicate combined sea heights around 3 to 5 feet. Expect little
change in heights through Monday. Combined seas is predicted to
increase to 4 to 6 feet Monday night.

An east trade-wind swell of 3 to 5 feet is expected through Monday
increasing slightly Monday night. Surf will be 5 to 7 feet on east
facing reefs with a foot or two increase by Tuesday. The surf on all
other will be 3 feet or less.


.Eastern Micronesia...
A weak trade-wind disturbance near Kosrae will maintain scattered
showers there through the night. This system is slowly moving
westward toward Pohnpei and Chuuk. Expect showers to continue to
develop over Pohnpei through the evening as this system approaches
the state. Showers will then gradually shift westward toward
Chuuk, bringing unsettled weather to Weno Monday morning. For
Majuro, IR satellite shows cirrus ceiling over the atoll. Even
though most of the cloudiness is due to cirrus, decided to
increase cloud cover to mostly cloudy for tonight. The dry pattern
that is setting up over Majuro will continue there through the
end of the week. This drier pattern will also drift westward,
bringing fair weather to Kosrae Monday night and to Pohnpei
Tuesday. A near-equatorial trough currently over western
Micronesia will develop eastward toward Chuuk and Pohnpei around
mid week. Increasing convergence to the north of the trough will
bring periodic showers to Chuuk Wednesday and to Kosrae Thursday.
This band of convergence will likely drift far enough north to
bring scattered showers to Pohnpei by the end of the week.

Trade-wind swell and wind waves generated by a trade-wind surge over
the western Marshall islands will maintain hazardous surf on Kosrae
thru tonight.


.Western Micronesia...
Discussion for Chuuk`s forecast can be found under Eastern
Micronesia above.

Modest converging winds north of a weak near-equatorial trough will
allow a few showers near Koror through Monday evening. Aided by
afternoon heating, a thunderstorm or two is also possible near Koror
Monday. Much drier air will filter into the region over night and
Monday, bringing a drier pattern to both Yap and Koror through the

Marianas Waters...None.


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