Area Forecast Discussion
Issued by NWS Tiyan, Guam

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FXPQ50 PGUM 180715
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
515 PM ChST Tue Jun 18 2019

.Marianas Synopsis...
Partly cloudy skies, isolated showers, and moderate trade winds
remain over the Marianas this afternoon. Combined seas at the buoys
are just under 4 feet.

&&

.Discussion...
Dry weather should persist for a while yet, as a subtropical ridge
north of the region keeps any significant systems south of the
Marianas. The only blip in this pattern is a minor disturbance that
will bring mostly cloudy skies Thursday night and Friday, but still
only isolated showers. The GFS brings southeast winds in for a day
or so Thu-Fri as the disturbance moves by over Yap, while the ECMWF
keeps the disturbance weaker and farther south. Prefer the steadier
ECMWF for now, which brings increased clouds through the islands
Thursday night and Friday while keeping winds from the east.

&&

.Marine...
Moderate east winds and 3-5 ft seas will persist until further
notice. Rip risk will remain moderate for the next few days along
east facing reefs.

&&

.Fire weather...
Isolated showers will provide little relief for critically dry
conditions on Guam. However, winds are expected to remain light
enough to preclude red flag conditions.

&&

.Eastern Micronesia...
Shower coverage continues to decrease across Eastern Micronesia. The
weak disturbance no longer shows evidence of a circulation as it
moves off to the west. Showers are now isolated across Kosrae and
Pohnpei States and are not expected to increase any further. The
main band of showers is well west of Kosrae, and Pohnpei is now
nearing the back side of the trough and is expected to continue to
dry out through Thursday. An active ITCZ is evident on the latest
ASCAT and satellite data. This is expected to spread in to the
Marshall Islands late Wednesday night or Thursday morning. Showers
are expected to increase to scattered across Majuro then spread
westward into Kosrae late thursday night or Friday and into Pohnpei
by Saturday morning.

&&

.Western Micronesia...
A surface trough moving westward from Pohnpei State will begin to
affect Chuuk Wednesday morning. This system is continuing to weaken,
so only isolated showers and thunderstorms are forecast for Chuuk.
The drier pattern currently moving in to Pohnpei will then reach
Chuuk by Friday morning, with drier conditions continuing through
the weekend.

The tropical disturbance south of Yap will continue to drift westward
over the next few days. This system remains fairly weak and shower
coverage has decreased over the region for the last couple of days.
Most of the activity is now south of Yap and only isolated showers
remain over Koror. Yap will be partly cloudy for the next couple of
days while enough moisture remains over Palau to keep Koror mostly
cloudy through the weekend. By Thursday night, a weak trough will
move into the region from Chuuk State to bring another round of
showers to Yap, while most of the activity will remain north of
Koror.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
Marianas Waters...None.

&&

$$

Middlebrooke/Kleeschulte


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