906
FXPQ50 PGUM 021954
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
554 AM ChST Wed Dec 3 2025

.Marianas Update...
Besides for a couple of isolated thunderstorms moving across the very
southern portion of Guam`s coastal waters this morning, satellite
imagery shows a dry trade-wind pattern across the Marianas, with the
primary cloud cover being a few cumulus clouds and a thin layer of
cirrostratus. A fairly dry trade-wind pattern will continue through
Thursday with winds around 15 to 20 mph, decreasing to 10 to 15 mph
Thursday as the subtropical ridge weakens and shifts eastward,
weakening the pressure gradient over the region. A weak-trade wind
trough is still expected to pass near the Marianas Thursday night and
Friday, bring scattered showers to the Marianas, with the greatest
potential thunderstorms expected around Guam and Rota.

The primary east swell and a pulse of long-period northeast swell
are still supporting surf up to 9 feet and a high risk of rip
currents along north and east facing reefs. These conditions are
expected to improve this evening as the two swells decrease. Seas of
6 to 8 feet are expected to drop slightly to 5 to 7 feet as well.
There is a moderate risk of lightning for Guam this morning due to
thunderstorms moving through the southern waters of Guam, and then
again for Guam and Rota Thursday night as a trough passes near the
Marianas.

&&

Tropical Systems Update...
Invest 93W is still rated as a Low by the Joint Typhoon Warning
Center. This means that tropical cyclone development is unlikely
within 24 hours. Satellite imagery ASCAT data suggest 93W is centered
near 13N134E, about 360 miles north-northwest of Yap Proper, with
the main low-level circulation still fairly broad and weak. Showers
and thunderstorms have redeveloped along the eastern edge of the
circulation over night. 93W is expected to slowly continue on its
westward trek over the next several days. For more information on
Invest 93W, see bulletins issued by the Joint Typhoon Warning Center
under WMO header ABPW10 PGTW.

&&

.Eastern Micronesia Update...
Besides for a weak trade-wind trough just west of Pohnpei, and
another trough between Majuro and the Dateline, a fairly dry trade-
wind pattern extends across the region according to satellite
imagery. Based on satellite trends, reduced the chance of showers at
Pohnpei from 50 percent to 30 percent, reduced showers at Kosrae from
scattered to isolated, and delayed scattered showers at Majuro to
the afternoon to better match when the trough between the Date Line
and Majuro will start to near the Marshall Islands. Newest model data
is also starting to support a drier pattern developing across the
region late this week and this weekend, as a Near-Equatoral Trough
develops south of the islands and drier air mixes in from the north,
with showers mostly associated with passing trade-wind troughs. Main
hazards over the next couple of days remains the high surf along
north facing reefs of Pohnpei and north and east facing reefs of
Kosrae due to the elevated trade swell and long- period north swell,
along with the potential for minor coastal inundation due to the
aforementioned swells and the elevated high tides due to the current
King Tide cycle.

&&

.Western Micronesia Update...
Scattered showers and isolated thunderstorms continue over Palau
as the convection within the westerly flow south of the Near-
Equatorial Trough (NET) has shifted northward and closer to Palau, as
it continues to be influenced by Invest 93W, located north-northwest
of Yap. Since 93W has not moved westward as quickly as models were
suggesting, the period of drier weather at Palau was delayed to
Thursday. Convergent flow north of the NET is also starting to
develop scattered showers near Yap. the NET will maintain periods of
scattered showers and isolated thunderstorms across Yap into the
weekend and bring increased convection back to Palau Thursday night
into the weekend. The narrow band of convergence over Weno saw a
decrease in convection overnight, but showers are starting to
redevelop, so delayed numerous showers to this afternoon to better
match current trends noticed via satellite imagery. Scattered
showers and isolated thunderstorm are expected to continue across
Chuuk through Thursday, before a drier trade-wind pattern across
eastern Micronesia shifts westward into Chuuk.

Combined seas of 3 to 5 feet near Palau and Yap are expected to build
slightly later in the week, reaching 4 to 6 feet. Seas will increase
at Yap around Thursday and at Palau later in the week. Seas will not
reach levels hazardous to small craft, however, seas will continue
to be choppy over the next few days due to a combination of north
swell, northeast trade swell and small wind waves. 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. High tide will be increasing over
the next few days due to the King Tide cycle associated with the full
moon Thursday night. With the background La Nina pattern, there is
the potential that this King Tide cycle could lead to some minor
coastal inundation Thursday and potentially into the weekend.


&&

.Prev discussion... /issued 613 PM ChST Tue Dec 2 2025/

Marianas Synopsis...
Satellite imagery shows partly cloudy skies and radar imagery shows
isolated showers over the Marianas. Altimetry shows 8 to 9 feet
while buoy data shows 7 to 9 feet. There is a High Surf Advisory
(HSA) and a Rip Current Statement for a High Risk of Rip Currents
(HRRC) in effect.

Discussion...
Mostly pleasant weather for the forecast period. Winds are expected
to be 15 to 20 mph for the next 24 or so hours and will gradually
taper down to 10 to 15 mph by the end of the week. The winds are
expected to build up to 15 to 20 mph again for the weekend. There is
a chance that the showers south of Guam`s coastal waters may build
northwards, however, this is low confidence in this coming to
fruition. This is due to Invest 93W heading more west than north. The
next chance for scattered or more showers is anticipated to be a
passing trade-wind trough around the end of the work week.

Marine...
The combination of the strong trade-wind swell and a long-period
north swell are hanging on longer than anticipated. To reflect this
the HSA and the HRRC were extended/continued until Wednesday
afternoon. Seas of 9 feet and buoy data of 7 to 9 feet support this
choice. Seas are expected to gradually taper down as the distant
systems move more eastward and the trades gradually relax a bit near
the weekend. Seas and winds are expected to remain below the 10 foot
and 22 knot thresholds for a Small Craft Advisory (SCA), however,
seas will be choppy.

Tropical Systems...
Invest 93W is a rated as Low by the Joint Typhoon Warning Center.
This means that tropical cyclone development is unlikely within
24 hours. Satellite imagery shows this system is near 13N135E, about
350 miles north-northwest of Yap Proper. Showers have greatly
diminished since the Tropical Weather Discussion was issued earlier
this morning. This feature is expected to continue on its westward
trek over the next several days. For more information on Invest 93W,
see bulletins issued by the Joint Typhoon Warning Center under WMO
header ABPW10 PGTW.

Eastern Micronesia...
A long-period northerly swell of 4 feet continues to interact with a
northeasterly trade swell to maintain high surf conditions, which
look to continue through Thursday, possibly longer. If this
continues to look likely toward the longer range, then the High Surf
Advisory will likely get extended in the next forecast issuance or
two. Additionally, minor coastal inundation concerns at Majuro will
continue through Friday.

Otherwise, embedded troughs within a fragmented ITCZ will keep
scattered showers and isolated thunderstorms going for most of the
forecast package.

Western Micronesia...
Latest satellite data shows fairly dry conditions across Yap Proper,
with scattered showers over Palau and scattered showers with
isolated thunderstorms over Chuuk. Altimetry shows seas between 3
and 5 feet across Yap and Palau and between 5 and 7 feet for Chuuk.

Scattered showers continue over Palau this afternoon as a weak
trough moves east in the westerly flow south of the Near-Equatorial
Trough (NET). As the trough moves through, it will also be pulled
farther north as Invest 93W moves off to the west. This will allow a
drier pattern to move into Palau Wednesday morning. This dry pattern
is expected to continue through For Yap, a dry pattern currently
over the island looks to change by Wednesday morning as this trough
approaches and is pulled farther north. Meanwhile, the NET looks to
move back over Yap as Invest 93W moves farther west, pulling the NET
along with it. the NET will maintain periods of scattered showers and
isolated thunderstorms across Yap into the weekend and bring
increased convection back to Palau Thursday night into the weekend.

For Chuuk, a narrow band of convergence over Weno is maintaining
scattered showers and isolated thunderstorms across the lagoon this
afternoon. This convergence looks to strengthen a bit over the next
couple of days with a couple of weak trade-wind troughs moving
through to interact with it. Convection looks to increase through
Wednesday, with numerous showers and isolated thunderstorms expected
Wednesday and Wednesday night. Convection will begin to decrease
Thursday with POPs (Probability of Precipitation) dropping to 50%
Thursday and down to 20% Thursday night through the weekend.

Combined seas of 3 to 5 feet near Palau and Yap are expected to build
slightly later in the week, reaching 4 to 6 feet. Seas will increase
at Yap around Thursday and at Palau later in the week. Seas will not
reach levels hazardous to small craft, however, seas will continue
to be choppy over the next few days due to a combination of north
swell, northeast trade swell and small wind waves. 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 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/Tropical Update: Schank
Marianas: Bowsher
East Micronesia: Doll
West Micronesia: Kleeschulte