Area Forecast Discussion
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FXPQ60 PGUM 202033
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
635 AM ChST Mon Aug 21 2017

.Marianas Synopsis...
Scattered clouds with isolated showers and a few thunderstorms
prevailed across the Marianas early this morning. Combined seas
were mainly 2 to 3 feet at the buoys.

&&

.Discussion...
An upper low was located north of Saipan and was moving generally
westward. It was taking shower and thunderstorm activity with it.
However, lingering moisture and the approach of yet another
surface trough and upper low will allow for additional showers and
isolated thunderstorms through Tuesday. Beyond that, some ridging
and drier air is expected to move in for the latter portion of
the week. No significant changes were made to the forecast. Seas
remain relatively quiet, in the 2 to 3 foot range. Surf is 3 to 5
feet on the eastern shores and lower elsewhere.

&&

.Eastern Micronesia...
A near-equatorial trough runs east-northeastward from southwest of
Chuuk across Pohnpei to a weak circulation just north of Kosrae,
then meanders eastward thru the Marshall Islands to well beyond the
Date Line. With light to gentle winds from Chuuk eastward to Kosrae,
the strongest convergence has been concentrating near the
circulation. Therefore, expect sporadic convection to continue near
Kosrae thru Tuesday. As this circulation gradually drifts westward
over the next few days, similar conditions will shift to Pohnpei by
Tuesday afternoon, Chuuk by Wednesday. In the wake of this
circulation, modest converging southeasterly winds should keep a
few thunderstorms near Kosrae and Pohnpei thru midweek, Chuuk thru
Thursday. Latest ASCAT satellite imagery indicates stronger surface
winds from the Marshall Islands eastward to beyond the Date Line.
This allows more frequent showers and thunderstorms to form near the
eastern portion of the near-equatorial trough. This unstable
conditions will begin to impact Majuro later tonight and last thru
midweek. As this portion of the near-equatorial trough progresses
westward during the second half of this week, anticipate unstable
weather to also persist near Kosrae, Pohnpei and Chuuk.

&&

.Western Micronesia...
The southeastern end of a monsoon trough is going to persist across
the Philippine Sea thru Tuesday afternoon. Converging southerly
winds to the south will couple with modest divergent flow aloft to
trigger periodic showers and thunderstorms near Koror and Yap thru
Tuesday. By Tuesday night, surface ridging should take shape which
will promote pleasant weather for both locations thru Wednesday.
Toward the weekend, converging trade winds will return with more
showery weather.

&&

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

&&

$$

Nierenberg/Chan



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