797
FXPQ50 PGUM 040713
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
513 PM ChST Sat May 4 2024

.Marianas Synopsis...
Partly cloudy skies with isolated showers are seen on satellite this
afternoon. Gentle to moderate trade winds prevail. Altimetry shows
seas between 3 and 5 feet.

&&

.Discussion...
Not much happening across the Marianas for the next several days. A
weak trough moving through the region brought a slight uptick in
showers today. This trough looks to be west of the islands this
evening, bringing drier conditions to the islands overnight. Another
trough will approach the Marianas Sunday, bringing increase in cloud
cover and another slight uptick in showers, though coverage looks to
remain isolated. Around Thursday night into Friday next week, another
more robust trough looks to move through the region, bringing a
slight chance of thunderstorms to the Marianas. More stable and
slightly drier conditions return for Friday into the weekend.

&&

.Marine...
Gentle to moderate trade winds will continue through the coming
week. Combined seas of 3 to 5 feet are expected to slowly build over
the next few days, reaching as high as 5 to 7 feet Tuesday. This is
due to a north to northeast swell moving through the region. Latest
model guidance is trending down with the heights of this swell, while
shifting the direction more toward the northeast. The building north
to northeast swell along with the trade swell is expected to produce
a moderate risk of rip currents along east facing reefs for the next
several days. The rip current risk is expected to become moderate
along north facing reefs Sunday, also continuing for the next several
days. With the north swell trending more toward the northeast, it is
unlikely that the rip current risk will become moderate along west
facing reefs.

&&

.Eastern Micronesia and Chuuk...
Trade convergence across the region remains fragmented, with showers
primarily developing along troughs moving across the region and the
weak convergence trailing behind the troughs. Chuuk Lagoon has been
cloudy but showers have been isolated as the trough that was nearby
yesterday continues to drift westward, and the trough currently
pushing through Pohnpei and generating numerous showers across
Pohnpei this evening, is not expected to reach Chuuk until about
Sunday evening. Pohnpei will see showers decrease from numerous to
scattered overnight, but convergence behind the trough should keep
scattered showers at Pohnpei into next week. Majuro remains on the
drier side, while Kosrae has been low-end scattered as weak
convergence and trade-wind troughs have been passing south of Majuro
and into Kosrae. Another trough has crossed the Date Line and is
moving towards Majuro, and it looks like it will start to lift
scattered showers into Majuro Sunday. Models also show trade-wind
convergence slowly building and moving across Kosrae and Pohnpei,
and then later into Chuuk, while also lifting northward into Majuro,
promoting scattered to, at times, numerous showers, especially
around Kosrae, Pohnpei, and Chuuk, next week. Thunderstorms are
expected to remain fairly isolated across the region over the next
few days due to the lack of strong divergent flow aloft. The
northern islands of the RMI, such as Wotje, and islands north of 7N
remain fairly dry and are expected to remain dry through the weekend
and the middle of next week. As the convergent trade flow starts to
lift north next week, some of these islands may start to see some
scattered showers, although models vary greatly on potential rainfall
amounts for the northern islands over the next 10 days, with some
like the Canadian Ensemble showing about 1.30 inches, with the ECMWF
being the most aggressive at about 4.3 inches, while the GFS sits
roughly in the middle.

Over the ocean, winds are expected to be from the northeast to east
and mostly gentle to moderate, occasionally becoming fresh at times,
especially around Majuro. Combined seas, as reported by altimetry,
are around 4 to 6 feet at Chuuk, Pohnpei, and Kosrae and up to 7 feet
around Majuro. Through the end of next week, not expecting any major
changes in wind or sea conditions.

&&

.Western Micronesia for Yap and Palau...
Scatterometer and satellite data show that the Near-Equatorial
Trough (NET) is still south of the main islands of Palau and Yap,
extending westward from a buffer circulation near EQ160E and exiting
the region near 3N130E, passing through a couple of very weak
circulations, one south of Chuuk and the other well south of Yap
state. Showers continue to develop along the north edge of the NET
and weak trade-wind troughs, which so far remain south of the main
islands of Palau and Yap Proper. Showers are expected to remain
south of Palau through at least Monday and potentially as long as
Thursday for Yap Proper and nearby islands as the NET and any
passing trade-wind troughs are expected to remain near and south of
5N. This pattern starts to change next week as models show the NET
lifting northward, as a broad circulation tries to develop within
the NET. This will increase the potential for showers at Palau Monday
night, but models have slowed the northward advance towards Yap
Proper to Thursday night. As usual, the GFS becomes the most
aggressive as it shows the circulation trying to develop as it pushes
north and then northwestward into the Philippine Sea, while the
ECMWF shows the circulation eventually dissipating and being
reabsorbed back into the NET. What both of these models support is
the potential for showers over Palau, and to a lesser extent at Yap,
late next week.

Winds over the ocean are expected to be fairly moderate and from the
northeast to east over the next several days. Combined seas are
expected to be around 4 to 5 feet through early next week, and this
matches well with current heights reported by the buoys near Palau
and Yap. Models are showing some north swell entering the region
around midweek, but this swell is currently expected to be 4 feet or
less, causing little change in overall sea heights, but may see some
elevated north surf around Wednesday.

&&

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

$$

Marianas: Kleeschulte
Micronesia: Schank