792
FXPQ50 PGUM 050738
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
538 PM ChST Sun May 5 2024

.Marianas Synopsis...
Partly cloudy skies with spotty showers and gentle to moderate trade
winds prevail across the Marianas this afternoon. Altimetry shows
seas between 3 and 5 feet.

&&

.Discussion...
Nothing exciting happening across the Marianas over the next few
days. The latest CIMMS MIMIC Precipitable Water product does show a
band of increased moisture moving into the Marianas. This is expected
to bring only a slight uptick in showers with skies becoming mostly
cloudy Monday into Monday night. Otherwise, a dry pattern looks to
continue through most of the week. Increasing instability along with
another increase in moisture near the end of the week will bring a
slight chance of thunderstorms to the region. Latest model guidance
shows the thunderstorm risk over Guam and Rota, however, chose to
include Tinian and Saipan for now since this is around 5 days out.

&&

.Marine...
Gentle to moderate trades winds will continue through the week.
Combined seas of 3 to 5 feet are expected to build a bit over the
next couple of days, reaching around 5 to 7 feet Tuesday into
Wednesday. This is due to a building north to northeast swell moving
into the region. Latest guidance shows this swell being fairly
short-lived for the Marianas, beginning to subside Wednesday or
Wednesday evening. The swells will result in surf high enough to
produce a moderate risk of rip currents along north facing reefs for
the next couple of days, and for east facing reefs through at least
the end of the week.

&&

.Eastern Micronesia...
A bulking convergence zone induced by various disturbances in the
Southern Hemisphere, will back-build across Pohnpei, Kosrae, and to
some extent as far east as Majuro through at least the middle of the
week. Showers and thunderstorms will increase in coverage and
intensity by Monday night at Pohnpei, before widespread heavy showers
and scattered thunderstorms with strong gusts push through by
Tuesday night. Meanwhile, peak shower intensity is expected at Kosrae
Tuesday and Tuesday night, but thunderstorm potentials remain lower
than at Pohnpei. Majuro will be the driest, with only low-end to
moderately scattered showers induced by a nearby trade-wind
convergence zone expected through midweek. Afterwards, on-and-off
showers are expected in the second half of the week at all three
locations.

Combined seas of 5 to 6 feet are expected at Pohnpei and Kosrae
until the next weekend, with a slight uptick in seas likely Wednesday
through Thursday night as a northerly swell trickles in. 6 to 7 foot
seas near Majuro are expected to increase by a foot or two by midweek
as well due to the aforementioned northerly swell, but seas are to
remain below hazardous levels to small craft.

&&

.Western Micronesia...
Satellite imagery shows a broad trade-wind trough along with
scattered showers moving into Chuuk this evening, while further west
the Near-Equatorial Trough, and most of the showers and thunderstorm
activity in the region, still remains south of Palau and Yap Proper
and just south of Eauripik and surrounding islands of Yap State. It
should also be noted that westerly winds are increasing along and
south of the equator from about 128E to 137E as winds flow into the
broad disturbance in the Arafura Sea, just south of Papua in the
southern hemisphere. It is this westerly flow near the equator which
helps to give rise to the circulation that the GFS, and to a lesser
extend the ECMWF and National Blend, show developing within the NET
by the middle of next week. As mentioned over the last few days,
models still vary greatly with the potential strength of the
circulation as the GFS is the most aggressive as it shows the
circulation trying to develop as it pushes north and then
northwestward into the Philippine Sea late this week, while the ECMWF
shows the circulation eventually dissipating and being reabsorbed
back into the NET.

How this pattern will truly evolve is still highly uncertain, but
some overall themes still remain. Through Wednesday, as the
circulation begins to develop, likely near or south of 5N between
138E to 146E, models keep most of the showers and thunderstorms in
eastern Yap State, southeast of Palau and Yap Proper, while at Chuuk,
increasing convergence northeast of the developing circulation will
continue to supported scattered showers and isolated thunderstorms
across the state, with showers becoming numerous around Tuesday and
Wednesday. The NET/circulation will then drift westward, slowly
decreasing the potential for showers at Chuuk through the weekend,
while increasing showers at Palau and Yap late this week and into the
weekend, hopefully bring some much needed rain to Yap Proper,
Ulithi, and Fais. Any discussion on the potential for strong or gusty
winds is still way to early due to the aforementioned variability
between the models on how the circulation may develop.

Winds over the ocean are expected to be gentle to moderate and from
the northeast to east over the next several days. Combined seas are
expected to be around 4 to 5 feet through Tuesday, and this matches
well with current heights reported by the buoys near Palau and Yap
and satellite altimetry data around Chuuk. Models are showing some
north to northeast swell entering the region Wednesday, but this
swell is currently expected to be 4 feet or less. This will
increase sea heights by about 1 to 2 feet and increase surf along
north facing reefs, though surf is not expected to become hazardous,
remaining below 9 feet.

&&

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

$$

Marianas: Kleeschulte
Eastern Micronesia: Montvila
Western Micronesia: Schank