FXPQ60 PGUM 202034

Area Forecast Discussion
National Weather Service Tiyan GU
635 AM ChST Thu Sep 21 2017

.Marianas Synopsis...
A mostly cloudy sky prevailed across the Marianas early this
morning. Doppler radar showed isolated showers and thunderstorms,
with a more concentrated area south of Guam. Combined seas were
generally 4 to 5 feet at the buoys.


There is an upper low to the west of the Marianas and the remnants
of a disturbance as well. These features have triggered some
showers and thunderstorms early this morning. The upper low is
expected to remain nearby for the next few days, but as surface
ridging moves in for later today into Friday, drier air is
expected and just some isolated showers are anticipated. Then
another trough is expected, but the bulk of the rain looks to
remain to the south at this time at least for Saturday. If later
guidance maintains this trend, then precip chances can be lowered
with later forecasts. Seas will likely remain in the 3 to 5 foot


.Eastern Micronesia and Chuuk...
A pronounced surface trough is steadily progressing westward from
near Kosrae this morning. Wet weather associated with it will
persist near Kosrae thru Friday afternoon, then reach Pohnpei late
this evening and Chuuk on Friday. A few residual showers and
thunderstorms will linger near Majuro this morning but much drier
trade winds should usher in pleasant weather by this afternoon.
This same dry air mass will also arrive at Kosrae by Friday
evening, Pohnpei and Chuuk this weekend. Afterward, another
surface trough from upstream just east of the Date Line will bring
back showery weather from east to west early next week.


.Western Micronesia for Yap and Koror...
A tropical disturbance is gradually lifting west-northwestward from
just north of Koror near 9N135E this morning. Moderate rain with
scattered heavier showers and a few thunderstorms will continue to
affect Koror until this afternoon. Nearly 2 inches of rainfall was
recorded near the Koror International Airport since yesterday
evening. By later this afternoon, surface ridging already over Yap
should build westward into Koror. This feature will provide fair
conditions for both places thru Saturday morning. Then wetness might
return later this weekend as a surface trough approaches the area
from near Chuuk.


Marianas Waters...None.


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