Area Forecast Discussion
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FXPQ60 PGUM 182102

Area Forecast Discussion
National Weather Service Tiyan GU
600 AM ChST Mon Mar 19 2018

.Marianas Synopsis...
Scattered clouds prevailed across the Marianas early this morning
with northeasterly trades. Combined seas were 6 to 8 feet at the
buoys. Latest radar showed an area of showers mainly southeast of


The dry weather pattern looks to continue for at least a few more
days with the trade wind regime in place until midweek. The
guidance has trended drier this cycle around the middle of the
week as a tropical disturbance to our south is weaker and slower.
Therefore, I have made Thursday just isolated showers for now. The
tropical disturbance is still forecast to move westward and some
guidance has it strengthening a bit as it moves by south of Guam/
However, the latest guidance is slower with the motion and there
is still some uncertainty with the track, as the ECMWF is further
north than the GFS. Nevertheless, with the slower motion it does
appear that the best chances of scattered showers would come
Friday and possibly into Saturday. For now, have left the
scattered showers on Friday. Did not add them for Saturday until
there is more clarity on both track timing.


Persistent northeasterly flow will remain in the 10 to 20 kt range
and seas generally 5 to 8 foot range for the balance of the week.
Depending on the track and strength of the tropical disturbance,
these values may need to be raised or lowered a bit. High rip
current risk continues into Wednesday and may need to be extended


.Fire weather...
Dry conditions continue and relative humidity values have bottomed
out in the lower 50s the last few days. Today looks similar or
even a tad drier. Wind speeds should be slightly higher than
Sunday, so it does appear that today could warrant the issuance
of red flag warnings.


.Eastern Micronesia...
Deep convection remains NNW of Pohnpei, sheared northward from the
low-level circulation which has dropped a bit southward to near
7N156E. Overnight scatterometry shows a much weaker and elongated
circulation than before. Showers and thunderstorms are mainly found
along the NE to SE periphery of the circulation, which is just east
and southeast of Pohnpei waters. After a fairly dry night, scattered
showers and a few thunderstorms will return to Pohnpei today. Models
show weak southeast winds building in which will usher convection out
of the area so much of the rest of the week will be somewhat drier.

Kosrae is in the quiet spot between the circulation near Pohnpei and
another disturbance to the east. Isolated showers and a few
thunderstorms are expected the next couple of days, but quieter
weather is expected later in the week as southeast to east winds
build in.

A slightly active ITCZ will keep Majuro wet through tonight, but
convection will gradually lift to the WNW the next couple of days
with drier weather expected by midweek.


.Western Micronesia...
Dry weather persists at all three locations this morning. Chuuk will
see some gradual change as the weak circulation to the east nears the
area the next couple of days, but models fail to show significant
rains affecting Chuuk at this time. Model consensus passes the
circulation near Chuuk on Tuesday then show the system dipping
southwest before beginning an even slower westward drift. Convergence
of low-level southeast winds and trade winds is expected to bring
increasing showers and thunderstorms to Chuuk, but not until late in
the week or weekend.

Yap and Palau will stay mostly dry for the week except for a slight
chance of thunderstorms today at Koror. Northeast winds will persist
into next weekend as clouds and showers build in late in the week in
advance of the slow moving circulation.


GU...High Rip Current Risk through Wednesday afternoon for GUZ001>004.

     Fire Weather Watch through this afternoon for GUZ001.

Marianas Waters...None.


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