543
FXPQ50 PGUM 251953
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
553 AM ChST Wed Nov 26 2025

.Marianas Update...
A minor surface trade-wind trough is approaching the Marianas from
the east, with widely isolated thunderstorms observed on Satellite
imagery. As such, introduced thunderstorms in this afternoon`s
forecast. Convection may increase slightly along the leeside of said
trough through tonight, with low-end scattered showers expected
Thanksgiving Day.

&&

.Eastern Micronesia Update...
A much-more active leading edge of the Intertropical Convergence
Zone (ITCZ) is bringing on-and-off showers and some thunderstorms
across much of eastern Micronesia, but the slow movement and spread
keeps the bulk of the showers currently away from the main forecast
points, with the exception being Majuro. Overnight, various
observation stations indicated higher winds and gusts near the deeper
convection, so introduced possibility for locally heavy rainfall and
higher winds for Majuro`s forecast for today. As these showers are
slow-moving, delayed them to this afternoon for Pohnpei, meanwhile
increased PoPs for Kosrae due to developing outflow boundaries
nearby.

&&

.Western Micronesia Update...
The Near-Equatorial Trough (NET) remained largely inactive for most
of the night, with the exception of a thunderstorm complex that
developed just northeast of Yap, so introduced thunder in Yap`s
forecast for this morning. Decreased shower coverage for Chuuk today,
as showers have been drying out just 200 miles to the east, so
expecting the convection to make it potentially by tonight. Palau`s
forecast remains unchanged, as diffusive northeasterlies continue;
the atmosphere remains stable and dry enough to keep island
convection to a minimum today.

&&

.Prev discussion... /issued 605 PM ChST Tue Nov 25 2025/

.Marianas Synopsis...
Satellite imagery shows mostly sunny skies with isolated showers over
the Marianas. Altimetry shows 7 to 8 feet to the east of the Marianas
near the 150E meridian and 6 to 7 feet to the west of the Marianas.
Buoy data shows around 7 foot sea heights.

&&

.Discussion...
The forecast remains intact. Throughout the forecast period the
chance of showers is expected to be 20 to 30 percent. The showers are
expected to peak Wednesday through Thursday and Saturday through
Monday. Model guidance shows that both peaks will be produced by
broad trade-wind troughs passing through the region. Winds are
expected to range between 10 and 20 mph with higher winds near
showers and higher elevations.

&&

.Marine...
Moderate to fresh trade winds will prevail across the region
through Wednesday, becoming gentle to moderate by the weekend.
Combined seas of 6 to 8 feet will gradually decrease by 1 to 2
feet toward the end of the week, as the elevated trade swell and
wind waves continue to become more relaxed. Although sea
conditions remain below levels hazardous to small craft, seas will
remain choppy for the next few days, especially over eastern
coastal waters. There is a high risk of rip currents along east
facing reefs, and a moderate risk along north facing reefs. The
elevated east swell will continue to produce high risk of rip
currents along east facing reefs through at least Wednesday night.
Once the trade swell starts relaxing, surf and risk of rip currents
will diminish.

&&

.Eastern Micronesia...
The main forecast challenge will be monitoring convective coverage
given a few subtle troughs moving through the region and associated
rainfall coverage/paraboloids. One such feature has departed Pohnpei
off to the west, with another such feature situated between Kosrae
and Pohnpei. Then, further east is another trough stretching from
south of Majuro near 6N169E to 8N180. This last feature also shows
increased surface convergence, which is poised to move into Majuro
later this evening and overnight. As such, went with high-end
scattered coverage (50 percent probabilities) there, and 30 to 40
percent probabilities elsewhere. This active pattern will continue
through the weekend with some models indicating showers could
increase to numerous coverage (55-74 percent potential) with later
troughs that develop, as they show increased surface convergence once
again, with a moisture pooling signature. We held off on this for
now as it`s in the day 5-7 forecast range, but we`ll keep an eye on
it.

Otherwise, light to gentle winds will periodically increase to
gentle to moderate, primarily as troughs are moving through due to a
slight increase in the pressure gradient and surface convergence.
Seas of 5 to 7 feet (locally a foot higher along Majuro`s northern
and eastern reefs) will gradually decrease by a foot or two towards
the weekend.

&&

.Western Micronesia...
Satellite early this evening reveals mostly fair conditions
throughout the region, with just isolated showers and partly cloudy
skies over the Republic of Palau and Yap State including Yap Proper.
The Near-Equatorial Trough (NET) remains over the region, extending
east into the region from over the southern Philippines, continuing
southeastward just south of Koror before passing through southern
Yap and Chuuk States. However, the NET is convectively inactive
throughout the region, with just a slight increase in showers to the
southwest of Yap within a weak band of convergence north of the NET
axis. A few more showers are seen near Chuuk associated with weak
troughs to the west and southeast of coastal waters, but satellite
and model trends point to drier conditions moving in for tonight.

Palau and Yap will see an increase in showers around Wednesday night
through Thursday as a trade-wind trough propagates west through the
area and the NET axis lifts slightly north. This interaction will
increase convergence and showers along the northern periphery of the
NET, but model trends keep most of the showers further east and the
pattern looks to remain fairly weak, so shower chances were only
increased from 20 to 30 percent in the forecast.

Chuuk will see a wetter pattern for the latter half of the workweek
as a broad, robust trade-wind trough approaches from the east and
interacts with the NET as it lifts north, greatly increasing surface
convergence across the area. Showers could increase to numerous for a
period or two by the end of the week, but certainty in the timing is
low, and for now shower chances were kept at high-end scattered (50
percent) for Thursday through Friday, with a slight decrease this
weekend.

There was little change to the marine forecast. Latest altimetry
data indicates combined seas of 5 to 7 feet near Palau and Yap and 6
to 8 feet near Chuuk. Light to moderate winds are expected across the
region throughout the forecast period, becoming mostly moderate for
Yap and Chuuk Wednesday through Thursday. Lighter winds are expected
for Palau with the NET axis lingering close by. Somewhat elevated
surf along north-facing reefs of Chuuk will continue to ease as the
trade swell relaxes over the next few days. Late in the weekend
through early next week, a long-period north swell looks to move
into the region, which may increase surf along north-facing reefs by
several feet, but no marine or surf hazards are expected at this
time.

&&

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

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

Marianas Waters...None.
&&

$$

Marianas/East and West Micronesia Update: Montvila
Marianas: Bowsher
East Micronesia: Doll
West Micronesia: DeCou