160
FXPQ50 PGUM 062004
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
604 AM ChST Sun Dec 7 2025

.Marianas Update...
A dry trade-wind pattern is still over the Marianas and will continue
over the next few days with winds around 10 to 15 mph. Newer model
data still shows a slight increase in winds around Wednesday, but the
GFS has backed off slightly from breezy conditions with winds up to
25 mph to more around 20 mph, while the ECMWF will supports breezy
conditions. Both models also still show the potential for a shearline
fragment (a band of increased cloud cover associated with a distinct
gradient of stronger winds to the north and weaker winds to the
south) moving into the Marianas towards the end of next week,
prolonging breezy conditions.

A High Surf Advisory and High Rip Current Risk Statement is still in
effect for north facing reefs, but Ritidian Point buoy has shown a
steady decrease in wave heights over the pass few hours which
supports that the northerly swell that pushed into the region
yesterday is diminishing. This trend supports the expiration time of
4 PM, with surf will likely dropping below hazardous levels of 9
feet and allow the risk of rip currents to become moderate. Gentle to
moderate trades will prevail the next few days. Combined seas of 6
to 8 feet are expected to taper down a foot by tonight, as the
seasonal trade swell and secondary northeasterly swell weaken
slightly. Winds are expected to increase to moderate to fresh later
this upcoming week as shear line fragments shift southward into the
Marianas.

&&

.Eastern Micronesia Update...
Satellite imagery shows spotty to scattered showers moving through
Pohnpei this morning, while fairly dry weather extends over Kosrae
and Majuro. There is a band of increased cloud cover extends
westward from south of Majuro and ends east of Kosrae, but it is
difficult if this band of cloud cover is associated with showers or
if it is more of a mid-level cloud deck based only on infrared
satellite imagery over night. Model data suggest showers will develop
within this band of clouds, and shift over Kosrae tonight. Otherwise,
an overall dry pattern is expected across the region over the next
few days.

A significant trade-wind swell continues to impact eastern
Micronesia. Altimetry data overnight suggest combined seas are
between 8 to 11 feet across Majuro, continuing the Small Craft
Advisory even as winds are expected to drop below 22 kt today.
Seas overnight were still 6 to 8 feet across Pohnpei and Kosrae.
Buoy data near Pohnpei showed seas were around 6 feet but over the
past 2-3 hours it has climbed to 8 feet and seas are expected to
continue to rise, supporting that the trade swell is increasing and
that seas will build to hazardous levels of 10 feet, as previously
forecasted, with the Small Craft Advisory going into effect this
morning for seas of 10 feet and winds up to 25 kt. Seas are expected
to elevated at Kosrae but remain below 10 feet and winds below the
22 kt threshold. The elevated trade swell will support high surf
along north and east facing reefs of Pohnpei, Kosrae and Majuro
through Monday afternoon. The Coastal Flood Advisory (CFA) for Majuro
was previously set to expire this afternoon around 3PM ChST (5PM
LST) but this would have occurred before the highest tide for the
day around 4PM ChST (6 PM LST). Also, coastal inundation was reported
yesterday evening at Majuro and all available data suggest flooding
will likely occur again this evening, so extend the CFA through late
tonight. The overall magnitude of the high tide is decreasing each
day, and the trade swell is expected to slowly subside over the next
few days, so not expecting another extension of the CFA at this
time.


&&

.Western Micronesia Update...
Satellite imagery this morning still shows a fairly dry regime
across much of western Micronesia. Scattered showers that were north
of Chuuk, associated with shallow troughing at the surface and
supported by strong upper-level east-northeasterlies and associated
divergence aloft, have shifted into eastern Yap State. Model data at
this time does not support these showers holding together long
enough to reach Yap Proper or Palau tonight, but this will be
something to watch.

Little change to the overall weather outlook, a dry trade-wind
pattern looks to persist across the region into next week. The Near-
Equatorial Trough (NET) is expected to remain south of most of the
islands and remain convectively quiet over the next few days. Showers
could build slightly near Palau and Yap early Monday as a weak
trade-wind trough propagates west into the area along the northern
periphery of the NET.

Altimetry data indicates combined seas around 5 to 7 feet across the
region, with 8 foot seas to the north and east of Chuuk. The High
Surf Advisory and Coastal Flood Statement remains in effect for
north-facing reefs of Palau and Yap as the elevated north swell will
persist for these locations. Decided to issue a High Surf Advisory
for north facing reefs of Chuuk starting this afternoon and
continuing through Monday afternoon as the north- northwest swell
that moved through the Marianas yesterday was slightly stronger than
expected, and as it mixes with the already elevated northeast swell
at Chuuk, this will likely push surf along north facing reefs up to 9
feet. The north swell is expected to slowly subside at Palau this
afternoon and should allow the High Surf Advisory and Coastal Flood
Statement there to expire as surf drops below 9 feet. Yap is expected
to remain around 9 feet slightly longer so the High Surf Advisory
and Coastal Flood Statement will continue through early Monday
morning. Seas will diminish slightly across the region toward the end
of next week as the north and trade swells relax. Winds will remain
light to moderate throughout the forecast period, becoming mostly
moderate for Yap and Chuuk from Sunday onward.

&&

.Prev discussion... /issued 605 PM ChST Sat Dec 6 2025/

Marianas Synopsis...
Gentle to moderate easterlies prevail today. Satellite imagery and
Doppler radar indicate shallow trade-wind showers moving across Guam
and Rota waters. Buoys and recent altimetry passes show seas are
about 5 to 7 feet.

Discussion...
A diffusive trade-wind pattern will continue to bring mostly
uneventful weather the next few days, followed by the arrival of a
trade-wind surge that will bring breezy conditions beginning around
midweek. Showers will remain minimal for several more days after,
followed by minor shearline fragments that may bring a little more
gusty showers and cloudiness toward the end of next week.

Marine...
Significant northerly swells generated by distant synoptic systems
are producing hazardous surf and a high risk of rip currents along
north facing reefs of the Marianas. As such, a High Surf Advisory
and High Rip Current Risk Statement are valid through Sunday
afternoon. Surf is then likely to fall below hazardous levels
thereafter as this pulse in northerly swell diminishes, which will
also allow rip current risk to drop to moderate along said reefs.
Combined seas of 6 to 8 feet are expected to taper down a foot by
Sunday night, as the seasonal trade swell and secondary northeasterly
swell weaken slightly.

Eastern Micronesia...
Satellite observations show isolated showers across Pohnpei and
Majuro and scattered showers across Kosrae. Altimetry data shows
combined seas of 8 to 10 feet across Majuro, and 6 to 8 feet for
Pohnpei and Kosrae.

A buffer circulation developed south of Kosrae overnight, which
enhanced convergence over Kosrae leading to numerous heavy showers
early this morning. The buffer circulation has weakened through the
day and the better convergence has shifted south and west of Kosrae.
Scattered showers and isolated thunderstorms will linger through the
evening before decreasing to isolated showers overnight. Quiet
conditions look to continue for Pohnpei and Majuro. Low-end (30%)
scattered showers will be possible for Pohnpei tomorrow and showers
decrease to isolated for the next several days. Showers look to
remain isolated for Majuro through much of next week as well.

A significant trade-wind swell is impacting eastern Micronesia this
weekend. Combined seas are between 8 to 10 feet across Majuro and 6
to 8 feet across Pohnpei and Kosrae. Seas are expected to rise
another 2 feet or so tonight and into Sunday. Conditions are
expected to become hazardous to small craft for Pohnpei Sunday
morning and should persist until early Monday morning. An easterly
swell of 5 to 7 feet is forecasted for tonight at Pohnpei. As the
trade-wind swell moves in, the swell direction is expected to become
more northeast. With a 8 to 9 foot northeast swell expected by
Sunday, surf will become hazardous for north and east facing reefs.
A north swell is currently in place but remains below 3 feet. The
north swell is expected to increase tomorrow, helping to make surf
hazardous.

Western Micronesia...
Satellite this afternoon shows a fairly dry regime across much of
western Micronesia. Scattered showers are seen to the north of Chuuk,
associated with shallow troughing at the surface and supported by
strong upper-level east-northeasterlies and associated divergence
aloft. Skies are mostly cloudy over Palau, from prior deep
convection to the southeast and left over from island-effect showers
earlier this afternoon. For Yap and Chuuk, skies are partly cloudy
with few to isolated showers over coastal waters.

A dry trade-wind pattern looks to persist across the region through
the remainder of the weekend and next week with little variation in
showers and wind strength. The Near-Equatorial Trough (NET) extends
east-southeast across the region, passing just south of Koror, and
remains convectively quiet along and north of the axis. Models
indicate showers could build slightly near Palau and Yap early Monday
as a weak trade-wind trough propagates west into the area along the
northern periphery of the NET.

Altimetry data indicates combined seas around 5 to 7 feet across the
region. The Coastal Flood Advisory at Chuuk was allowed to expire at
5 PM ChST with high tides on the diminishing end of the latest King
Tide cycle, and with no reports of minor coastal inundation over the
last few days. However, slightly elevated north swell and building
trade swell will maintain elevated surf along north and east facing
reefs of Chuuk over the next few days, and occasional minor coastal
splash-over will be possible near high tide times. The High Surf
Advisory and Coastal Flood Statement remains in effect for north-
facing reefs of Palau and Yap as the elevated north swell will
persist longer for these locations. Seas will diminish slightly
across the region toward the end of next week as the north and trade
swells relax. Winds will remain light to moderate throughout the
forecast period, becoming mostly moderate for Yap and Chuuk from
Sunday onward.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk until 4 PM ChST this afternoon for GUZ001.

     High Surf Advisory until 4 PM ChST this afternoon for GUZ001.

MP...High Rip Current Risk until 4 PM ChST this afternoon for MPZ001>003.

     High Surf Advisory until 4 PM ChST this afternoon for MPZ001>003.

Marianas Waters...None.
&&

$$


Marianas/East and West Micronesia Update: Schank
Marianas: Montvila
Eastern Micronesia: Williams
Western Micronesia: DeCou