Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 250613
Area Forecast Discussion
National Weather Service Tiyan GU
415 PM ChST Tue Oct 25 2016
Moderate east trade winds and isolated showers are seen across the
Marianas. Visible satellite shows the leading edge of a weak trade
wind surge to the west that brought passing showers to the islands
this morning. Ipan and Ritidian buoys show combined seas of 3.5 to
5 feet, with a north swell observed at the Ritidian buoy.
Only minor changes were made to the grids through the weekend as
the relatively drier weather pattern in place will persist the
next few days. Models showed a slight uptick in showers today
through Thursday. Brief, passing showers this morning were
associated with a trade wind surge pushing through the region.
Visible satellite imagery shows only spotty trade-wind showers
upstream of the Marianas, but deeper moisture well to the south
is associated with a disturbance between Koror and Chuuk. Moderate
trades will persist through the end of the week. In the long-
range, models show a little more moisture for the weekend, so
added more clouds and isolated thunderstorms to the grids for that
time frame. Could see lighter winds by early next week shifting to
Ritidian buoy shows the north swell component building in from the
north. Daytime surf obs show maximum surf of 5 to 6 feet along the
north-facing exposure of Agana Boat Basin. North swell will
continue through the end of the week, building by another foot by
Wednesday night. Combined seas of 4 to 5 feet could build another
foot by Thursday with that increased north swell. North swell and
combined seas will subside late in the weekend by 1 to 2 feet.
Ascat Analysis indicates a weak double-circulation pattern over the
northern RMI, while satellite shows the larger scale pattern of
surface troughing and showery weather is centered at about 9N170E.
Showers and possible thunderstorms will linger at Majuro overnight
at least and isolated thunderstorms will persist the next few days.
For the next several days, models keep the focus of convection over
northern parts of the RMI and Pohnpei and Kosrae States. GFS and
ECMWF indicate the circulations will drift across the Kwajalein
area and gradually weaken within the trough, but it will need to
be watched. Majuro/Kalo Buoy shows combined seas of 3 to 4 feet on
the east side of Majuro.
Chuuk State; light to gentle winds will persist the next few days.
Chuuk is between significant weather makers at this time, but the
atmosphere will be moist and unstable enough for spotty showers and
thunderstorms at times.
Yap and Koror; Ascat Analysis indicates a weak circulation southeast
of Koror near 3N138E. Showers and thunderstorms are in patchy areas
northeast and west of the circulation. Satellite trends indicate
spotty showers will move across Yap and Koror as the circulation
drifts westward in the coming days. In the longer term, models still
hint at a monsoon trough pattern developing along 5N, possibly with
a weak circulation forming west of Chuuk late in the week.