Area Forecast Discussion
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FXPQ60 PGUM 241849

Area Forecast Discussion
National Weather Service Tiyan GU
450 AM ChST Sun Jun 25 2017

.Marianas Synopsis...
An upper-level low is seen on satellite data to the north of
Saipan. A developing tropical disturbance is also present to the
east of the Marianas. Isolated showers and thunderstorms are
present over the coastal waters, with scattered showers and
isolated thunderstorms to just east of the waters. Latest buoy
data shows seas have increased to between 4 and 6 feet.


A TUTT cell to the north of Saipan and an approaching tropical
disturbance remain the focus of the forecast through Monday. These
two systems will continue to interact with each other to maintain
an unsettled pattern over the Marianas through Monday night. Only
isolated showers and thunderstorms are seen over the Marianas this
morning, however, scattered to numerous showers and isolated
thunderstorms are evident just east of the coastal waters and are
expected to move into the area a little later this morning. Over
the past hour, showers and a thunderstorm have developed just
south of Guam and near Cocos Island. Expect cloud cover and
shower coverage to increase quickly this morning as the
disturbance moves closer to the islands. The TUTT cell has begun
to move a bit faster westward and will likely clear the area a
bit earlier than previously expected. The disturbance, however,
will continue to affect the region through Monday night. Showers
are expected to decrease to isolated by Monday morning, but the
risk of thunderstorms will continue until early Tuesday morning.

A drier trade-wind pattern will return for Tuesday and Wednesday,
with another weak trade-wind disturbance approaching the Marianas
Thursday, bringing an unsettled pattern back to the islands for
the end of the week.


Latest buoy observations show seas between 3 and 6 feet over the
waters. Latest ASCAT analysis shows winds of 20 to 25 knots to the
east, on the northern side of the disturbance. As the disturbance
slowly drifts westward over the next couple of days, these winds
could move over the coastal waters. If this occurs, a Small Craft
Advisory for winds will be a possibility. Through tonight, gusts
to 25 knots are also possible near showers and thunderstorms.


.Eastern Micronesia...
A pattern of converging winds and areas of widespread showers have
developed across much of this area. There are showers from eastern
Chuuk State over southern Pohnpei and Kosrae States, and across the
Marshall Islands to northeast of Majuro. These areas of showers are
edging slowly toward the west-northwest. A little drier weather may
follow by mid-week, especially at Majuro on Monday and Tuesday, but
model guidance indicates another area of trade-wind convergence and
patchy showers will move from across the Date Line into Eastern
Micronesia later in the week.


.Western Micronesia...
ASCAT Analysis indicates weak circulations southeast of Guam near
12N147E and just north of Koror near 9N135E. Patchy showers and
thunderstorms persist near Yap, while skies over Koror are partly
cloudy this morning. For the next couple days, most of the showers
moving west from across the Mariana Islands are expected to remain
north of Yap and Koror while a ridge of high pressure develops over
far Western Micronesia. But, weather conditions could yet become
unstable over the area, especially later this week.


Marianas Waters...None.


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