Area Forecast Discussion
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FXPQ60 PGUM 272116

Area Forecast Discussion
National Weather Service Tiyan GU
551 AM ChST Wed Jun 28 2017

.Marianas Synopsis...
An upper low was located to the northeast of the Marianas and is
slowly approaching. This feature will bring scattered showers and
isolated thunderstorms through the weekend. The buoys are
reporting 3 to 5 feet of combined seas.


The upper low will be the predominant weather feature for the
remainder of the week into the weekend. It appears as if there are
two main pieces of energy with it and timing of those is
difficult. However, it does appear the first will move through
later tonight into Thursday so have increased shower chances to
scattered during this time. The second wave looks to be
sometime Friday into Saturday, but until we get closer have
maintained the current forecast for now with isolated for now.
Timing could always change faster or slower, but the remainder of
the week into the weekend looks unsettled.

Latest guidance also keeps seas elevated a bit longer as the upper
low moves through.


.Eastern Micronesia...
A moderate trade-wind surge is migrating westward from the Marshall
Islands this morning. A trade-wind convergent zone can be seen along
the southern extent of the surge, south of Pohnpei, Kosrae and near
Majuro. Showery conditions will continue near Majuro thru Thursday
night. As the convergent zone gradually shifts west-northwestward,
wetness will also reach Kosrae late this afternoon and Pohnpei late
this evening. Weakening trade winds toward this weekend should allow
shower activity associated with the convergent zone to decrease
across the region.


.Western Micronesia...
A weak circulation and related surface trough have pulled farther
west farther away from Chuuk this morning. This should promote a
brief period of drier weather near Chuuk today and early this
evening. Afterward, a trade-wind convergent zone shifting west-
northwestward from Eastern Micronesia will arrive with more unstable
conditions thru Friday. Things will improve this weekend as trades
weaken across the region.

The weak monsoon trough over the Philippine Sea north of far Western
Micronesia yesterday has dropped southward over Koror and Yap as a
near-equatorial trough and connected to a weak circulation southwest
of Chuuk this morning. Modest converging winds near these features
will couple with an upper-level trough moving westward across the
area to trigger isolated thunderstorms near Koror and Yap thru
Thursday night. Periods of scattered showers are also possible and
future shifts will need to upgrade shower coverage when necessary.
As the circulation slowly pulls northwestward over the next couple
of days, it will lift the near-equatorial trough northward away from
both locations. Then a surface ridge should from over the region by
this weekend and promote fair weather into next week.


Marianas Waters...None.


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