744
FXPQ50 PGUM 012015
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
615 AM ChST Tue Dec 2 2025

.Marianas Update...
The band of showers has shifted west, leaving the Marianas quite a
bit drier this morning. This was already handled well in the
forecast, so hardly any changes were made. Showers could increase
again Thursday or Thursday night, but will then diminish again for
the weekend. The transition to dry season is moving right along, with
the KBDI having been temporarily knocked back down 259. The buoys are
reading 7 feet from the northeast.

&&

.Marine...
Large north swell continues to roll through the Marianas as a result
of a winter storm that moved off Japan last week, along with large
east swell related to 93W and elevated trade winds. Ipan and Ritidian
buoys show seas of 7 feet at this time, and seas are forecast to be 7
to 9 feet through Wednesday. A High Surf Advisory and a High Risk of
Rip Currents are issued already. Currently a Small Craft Advisory is
not expected, but these conditions are only just below criteria.

&&

.Tropical Systems...
Invest Area 93W is currently centered north of Yap and west of Guam.
It is currently rated as having a low chance of becoming a tropical
cyclone within the next 24 hours, and will likely be outside of
Micronesia before it does. For more information on 93W, please see
the Significant Tropical Weather Advisory from the Joint Typhoon
Warning Center under WMO header ABPW10 PGTW.

&&

.Eastern Micronesia Update...
An Inter Tropical Convergence Zone is keeping Eastern Micronesia well
watered. Pohnpei and Majuro will be the more showered islands, while
Kosrae will have only widely scattered showers today, but will likely
have more later in the week. The ITCZ ends up feeding into the trough
that is feeding into Invest Area 93W.

&&

.Western Micronesia Update...
Koror, Palau and Yap have areas of showers floating by, so the
scattered showers in the forecast were working well. Chuuk should
have more substantial rainfall today, so their numerous forecast was
even better. No changes were needed for today`s forecast in Western
Micronesia. The showers are mainly related to Invest Area 93W and a
trough trailing off the east-southeast, which resembles a monsoon
trough, but it`s hard to pinpoint whether it really is or not. The
time of year is starting to suggest not, since this isn`t an El Nino
year.

&&

.Prev discussion... /issued 616 PM ChST Mon Dec 1 2025/

Marianas Synopsis...
Visible satellite and radar imagery show patchy showers across the
CNMI and an area of showers approaching southeast Guam waters. Buoys
around Guam reveal seas around 6 feet this afternoon.

Discussion...
A tropical disturbance, Invest 93W, continues to move westward away
from Guam, and will make way for fairer weather for much of this
upcoming week. This is evident in the CIMMS MIMIC TPW product,
showing a drier air mass approaching from the east. Model guidance
show convergent trades following the disturbance that may bring an
uptick in showers and/or cloud cover at times this week for Guam and
Rota, then the a trade-wind trough may pass through around Thursday,
bringing another period of scattered showers to the region.

Marine/Surf...
Trade swell and a pulse of long-period north-northeast swell are
producing hazardous surf along north facing reefs and a high risk of
rip currents along north and east facing reefs. This is now expected
through Tuesday afternoon for north facing reefs so have extended the
High Surf Advisory accordingly. The high rip risk is still expected
to continue for east facing reefs through at least Wednesday
afternoon. Refracted swell waves are expected to slightly add to surf
along south and west reefs, so a moderate risk of rip currents
is expected along south and west facing reefs through at least
Tuesday night. Moderate to fresh trades and combined seas of 6 to 9
feet are expected through Wednesday, then conditions gradually
subside to gentle to moderate winds and 5 to 7 foot seas late week.

Tropical Systems...
A tropical disturbance, Invest 93W, remains an open trough at the
surface, with a broad vorticity signature at 850mb north-northeast of
Yap Proper. A location is difficult to ascertain as there is no low-
level circulation yet, but is roughly located near 13N141E, well west
of the Marianas. Convection remains unorganized with flareups of
convection along the northern portion of the disturbance with some
bands of convection moving in from the southeast. 93W is still rated
sub-low for significant development, although it may start to develop
a broad, low-level circulation as it continues west-northwest and
passes north of Yap overnight and Tuesday morning.

Eastern Micronesia...
Satellite observations show scattered to numerous showers and
isolated thunderstorms across the region. Altimetry and buoy data
show combined seas between 7 and 9 feet across the region.

The main change with this forecast package was to increase PoPs
across Pohnpei and Kosrae through the next few days with numerous
showers expected across Pohnpei and scattered showers expected
across Kosrae. The forecast through Wednesday remains unchanged for
Majuro. Towards the latter half of the week, guidance shows a
dominant surface ridge expanding into eastern Micronesia. This looks
to suppress the ITCZ and associated convection southward, bringing
isolated showers to Majuro by Wednesday night and Pohnpei by Friday.
Kosrae looks to remain in scattered shower coverage through the
period due to being further south. A tightening pressure gradient
may also lead to  fresh to strong winds for Majuro late this week.
Winds could potentially approach small craft conditions for Majuro
late this week.

Combined seas range between 7 to 9 feet across the region.
Conditions hazardous to small craft were likely felt across Majuro`s
coastal waters last night and early this afternoon, however, a Small
Craft Advisory was not considered due to the forecasted combined
seas falling below 10 feet this afternoon and remaining below 10
feet through at least Wednesday. A High Surf Advisory was issued for
north facing reefs of Pohnpei, and north and east facing reefs of
Kosrae through Thursday afternoon. A significant weather system well
northeast of the region is producing a long period north-
northeasterly swell. Data from Pohnpei`s buoy shows a 7 to 8 foot
swell with an average period of 13 seconds, which is producing large
breaking waves of 8 to 10 feet. A Coastal Flood Statement was issued
for Majuro due to the same distant swell and the lunar cycle causing
minor coastal flooding. Isolated minor coastal flooding is expected
through at least Friday afternoon during times of high tide. While
uncertain at this time, there is some chance for moderate flooding to
develop, which would warrant an issuance of a Coastal Flood
Advisory. As such, conditions will be monitored regularly over the
coming days as King Tides continue to develop.

Western Micronesia...
An unsettled pattern produced by the Near-Equatorial Trough (NET),
will continue to bring periods of scattered showers and some
thunderstorms to Palau and Yap the next several days. As 93W
continues toward the Philippines, the NET will follow suit, with
winds switching directions abruptly to the southeast and south toward
the weekend. Most of the convection will be concentrated in the
leading edge of the ITCZ coming up on 93W, bringing a compact zone of
deepening convection that will produce intense showers and
thunderstorms over Chuuk through at least Wednesday. Occasionally
near-gale force gusts are likely to develop near the heaviest showers
Tuesday, while sustained winds may drastically change throughout the
day, remaining largely in the easterly direction. In addition, the
upcoming King Tides, along with already elevated seas caused
easterly and northerly swells (as well as localized wind waves), may
produce nuisance coastal flooding during times of high tide beginning
around Thursday. If conditions warrant, a Coastal Flood Statement may
be issued if coastal flooding potential increases, with confidence to
increase as we come closer to the next King Tide cycle.

Combined seas of 4 to 6 feet are expected near Palau and Yap for much
of the forecast period, as northerly swells, easterly swell, and
wind waves continue to trickle into the area. Even if seas do not
reach levels hazardous to small craft, seas will continue to be
choppy over the coming days. Combined seas of 5 to 8 feet near Chuuk
may drop a foot or two in the second half of the week as trade swell
weakens.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through Wednesday afternoon for GUZ001.

     High Surf Advisory until 5 PM ChST this afternoon for GUZ001.

MP...High Rip Current Risk through Wednesday afternoon for MPZ001>003.

     High Surf Advisory until 5 PM ChST this afternoon for MPZ001>003.

Marianas Waters...None.
&&

$$


Marianas/East and West Micronesia/Tropical Update: Stanko
Marianas/Tropical: Cruz
East Micronesia: Williams
West Micronesia: Montvila