Area Forecast Discussion
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Area Forecast Discussion
National Weather Service Tiyan GU
600 PM ChST Fri Sep 30 2016


A low-level outflow boundary emanating from the eastern flank of
TS Chaba is bringing showers and a few thunderstorms to Guam this
afternoon, but the rest of the Marianas are partly cloudy with
isolated showers and moderate south winds. Seas are around 5 feet
at the Guam buoys.


Wind and wave grids were refreshed out several days, but that only
resulted in minor changes to the forecast. The next disturbance
expected to approach from the east is still due by Sunday morning,
but it should not be quite as significant as the previous one,
which is now TS Chaba. Winds will rise back to moderate on Sunday,
but only slight rises in seas are expected by Monday before they
fall back again Tue-Wed. The band of showers currently moving over
Guam is expected to die out before reaching the CNMI, though it
will need watching. Saturday and Saturday night should be fairly
pleasant before the weather deteriorates again by Sunday.


.Eastern Micronesia...
A low-level circulation and its associated trough are seen between
Chuuk and Pohnpei this evening. Wet weather related to this system
will continue to affect Chuuk thru Saturday evening and Pohnpei
thru Saturday. Residual showers will also linger near Kosrae until
late tonight. Drier weather is going to arrive at Kosrae on
Saturday, Pohnpei and Chuuk near Sunday. For Majuro, isolated
trade-wind showers are expected thru Saturday.

A trade-wind convergent zone can be seen from east of the Marshall
Islands at 5N180...stretching east-northeastward to beyond 160W at
10N. This feature is slowly sliding westward toward the
Marshalls. Therefore, shower coverage should gradually increase
near Majuro starting Saturday night with thunderstorms flaring up
by Sunday. As this zone progresses farther westward, it will also
bring similar conditions to Kosrae and Pohnpei near Sunday, then
possibly Chuuk early next week.


.Western Micronesia...
Reasoning for the Chuuk forecast is included under the Eastern
Micronesia section above.

Tropical Storm Chaba near 14N138E is turning northwestward over
the Philippine Sea this evening. Converging southwest to south
winds feeding toward Chaba will maintain sporadic convection near
Yap thru Saturday and Koror until Sunday afternoon. Once Chaba has
tracked north of 20N on Sunday evening, a surface ridge in its
wake should calm things down for both places. Afterward, a low-
level circulation and its associated trough from Eastern
Micronesia might bring more wetness to the region early next week.

With a northwest track across the Philippine Sea, components of a
northwest swell generated by Chaba might reach the Republic of
Palau and Western Yap State over the next couple of days. This
will keep seas and surf slightly higher but should remain below
hazardous levels.


Marianas Waters...None.



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