Area Forecast Discussion
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FXPQ60 PGUM 281936

Area Forecast Discussion
National Weather Service Tiyan GU
536 AM ChST Mon May 29 2017

.Marianas Synopsis...
Gentle to moderate trade winds and isolated showers will dominate
over the Marianas waters today as a dry season trade-wind regime
maintains an iron grip over the region.


The presence of the Mei-yu front, or plum rains, between the
Marianas and Japan is forcing the subtropical ridge southward so
that it lies just north of the Marianas. This will maintain the
current dry season trade-wind regime through the forecast period.
A weak trade-wind disturbance could cause a brief uptick in clouds
Tuesday night and Wednesday, otherwise the only change will be the
wind speeds dimnishing from gentle to moderate today to more like
light by Tuesday or Tuesday night. Accordingly seas will drop from
3 to 5 feet today to between 2 and 4 feet by Tuesday night, and
perhaps even 2 to 3 feet around Thursday. The GFS paints a
significant rainfall event around day 10, will just watch that for
now and see if it even makes it to day 7.


.Eastern Micronesia...
Only isolated trade wind showers are seen across the region from
Pohnpei to Majuro this morning. More showers and isolated
thunderstorms are present well south of Pohnpei and Kosrae near
the equator. A seasonably dry pattern will remain in place the
next few days as an upper-level trough slowly shifts southward.
Showers will increase late in the week across the region as this
trough provides a more favorable environment for showers and
isolated thunderstorms. For now, most of the much-needed moisture
looks to keep just south of 10N.


.Western Micronesia...
IR satellite imagery shows more moisture in western Micronesia
this morning with isolated thunderstorms south and southwest of
Chuuk to south of Yap, and scattered showers and isolated
thunderstorms near and west of Palau. A relatively dry pattern
will hold in place at Chuuk the next few days, but moisture could
increase for the last half of the week. At Yap, similarly dry
conditions should persist there with moisture keeping just to the
south. Isolated thunderstorms could build northward tonight and
Tuesday into the Yap waters. At Palau, a generally wetter pattern
will persist through Tuesday night. An upper-level trough will
help trade wind showers develop vertically into deeper convective
cells thus providing more showers to the region. For now, much of
this weather is displaced to the west of Koror.


Marianas Waters...None.


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