035
FXPQ50 PGUM 300907
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
707 PM ChST Sun Nov 30 2025

.Marianas Synopsis...
Visible satellite and radar imagery show mostly cloudy skies and
scattered showers across the region this afternoon, with a few
thunderstorms that developed around Guam and Rota coastal waters.
Buoy and altimetry data show seas have increased to 6 to 8 feet with
the arrival of northerly swell.

&&

.Discussion...
An unsettled weather pattern continues, mainly across Guam and Rota,
linked to a weak tropical disturbance to the south, JTWC Invest 93W.
As 93W passed to the southwest of Guam over the next 24 hours, model
guidance continues to show a similar distribution of convection,
with the bulk of showers and thunderstorms over Guam and Rota, and
relatively lower shower coverage over Tinian and Saipan. The
trailing convergence in the wake of 93W that was mentioned in
previous discussions now looks to have shifted slightly southward,
which would result in a return to partly cloudy skies and isolated
showers by midweek.

&&

.Marine/Surf...
Moderate to fresh trades will prevail across the region through
Tuesday night, as a tropical disturbance is expected to maintain
scattered showers and isolated thunderstorms over the next couple
days, mainly across Guam and Rota. Combined seas of 7 to 9 feet
are expected through Wednesday as northerly swell moves through
the region, generated by a distant low pressure system.
Afterwards, conditions gradually subside to gentle to moderate
winds and 5 to 7 foot seas late week. Trade swell and the 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 expected through at least Monday
afternoon for north facing reefs, with the high rip risk continuing
through at least Wednesday afternoon for east facing reefs.

&&

.Tropical Systems...
A weak tropical disturbance, centered roughly near 11.3N 142.5E, has
been opened as Invest 93W by the Joint Typhoon Warning Center (JTWC).
Invest 93W is currently designated as a sub-low, which means that,
although it is being monitored, development into a significant
tropical cyclone is not expected within the next 24 hours. Invest 93W
is highly disorganized and a low-level circulation center is not
discernible from visible satellite imagery. CIMSS 850-700 mb
satellite analysis does show a vorticity center around this area to
the south of the Marianas, but it is broad and disorganized.
Convection has been building within 93W through the afternoon just
north to northwest of the approximate center, mainly just west of
Guam coastal waters. Models show Invest 93W steadily developing over
the next few days as it shifts west across the Philippine Sea.
Notably, the ECMWF is running more aggressively than the GFS,
developing a circulation by Monday night, about 24 hours sooner than
the GFS. Even with the more aggressive model solutions and high
degree of uncertainty, Invest 93W is not expected to bring any direct
impacts to the region, exiting west of 130E around Thursday or
Friday. However, 93W does look to support a wetter pattern across
western Micronesia and the Marianas for much of the week.

&&

.Eastern Micronesia...
Much like the end of last week, the tabular wave data from the GFS
has been about a foot to a foot and a half high (ironically...as
it`s usually a foot to a foot and a half low). This looks to be a
result of the higher waves getting shunted further east between 10N
and 20N, delaying the arrival of a higher swell. As such, waves were
lowered for the next 24 hours. However, seas and swell will increase
later Monday, as the source region for these higher waves is to the
northeast, it`s just taking a little longer for the higher swells to
arrive.

The other item of interest is convection within the ITCZ, mainly
east of 170E (near Majuro eastward). Here, surface convergence is
weaker. Upstream satellite imagery east of the Date Line is also
unimpressive in terms of convective development and moisture depth
until you get east of 170E. This matches well with the latest GFS GDI
forecasts. Thus, Majuro has slightly lower rainfall
coverage/probabilities in the forecast for the first half of the
week compared to Pohnpei and Kosrae.

Some minor inundation is possible at Majuro, as King Tides interact
with the core of higher winds/waves centered north of Majuro. This
looks to begin Tuesday afternoon and continue for at least a few
days.

&&

.Western Micronesia...
Satellite early this evening shows scattered showers building over
and just east of Palau, north of the Near-Equatorial Trough (NET)
axis which extends east-southeast across much of the region, from
6N130E to around 1N153E. There is an area of broad, elongated
cyclonic turning within the NET, centered roughly just southwest of
Koror, and showers are increasing within the convergent flow just
northeast of this weak vorticity center. East to northeast of Yap,
showers are scattered to numerous, associated in part with JTWC`s
Invest 93W, which is centered roughly near 11.3N 142.5E, and with a
broader trough that extends northwest from over Ulithi and Fais near
10N140E, to around 15N138E. For Chuuk, scattered to numerous showers
are seen just west of coastal waters within an area of low-level
convergence and troughing, but the upstream environment looks fairly
clear for this evening. Showers are expected to build near Chuuk
overnight as convergence broadly increases along the backside of the
broad trough and Invest 93W, south-southwest of the Marianas.

Shower chances across the region will depend in part on the
development and strength of Invest 93W as it moves westward, passing
just north of Yap around Monday night, likely still as a robust open
surface trough. The trailing convergence behind 93W will maintain
scattered showers for Yap and Palau throughout much of the week, but
models generally favor most of the showers and thunderstorms further
north. Chuuk will see scattered showers throughout the week, building
to numerous at times as a series of disturbances push west to
northwest through the area, first around Monday night and again
around Wednesday. Certainty of timing remains low and shower chances
for Chuuk this week will likely see more significant changes in later
forecast packages.

Altimetry data indicates combined seas around 3 to 5 feet near Palau
and 4 to 6 feet near Yap and Chuuk. The primary northeast trade
swell is expected to remain fairly steady through the next few days,
but a long-period north swell is still expected to move in around
Monday, building surf along north-facing reefs. Surf is expected to
remain below hazardous levels of 9 feet for Palau and Yap with most
of the swell energy further east near Chuuk, but may come up near 9
feet for Chuuk around midweek. Additionally, minor inundation will be
a concern, as the next King Tide cycle will occur with the full moon
on December 4th, and high tides will be elevated a few days before
and after the full moon. Based on current tide predictions, the risk
for minor coastal inundation will peak Thursday, December 4th to
around Monday, December 8th.

&&

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

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

Marianas Waters...None.
&&

$$

Marianas: Cruz
East Micronesia: Doll
West Micronesia: DeCou