252
FXPQ50 PGUM 261922
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
522 AM ChST Thu Nov 27 2025

.Regional Overview...
The Near-Equatorial Trough (NET) that spans across much of western
Micronesia, will be the primary driver for weather across the region
through at least the weekend. A broad zone of convergence is
expected to continue forming along the northern flank of the NET axis
and anchor along 10N as multiple trade-wind troughs form within and
move west, bringing intense showers and thunderstorms to the
easternmost edges near Kosrae this morning, followed by Pohnpei and
Chuuk beginning later this afternoon, and then the Marianas by early
next week.

.Marianas Update...
This Thanksgiving, upper-level features are enhancing the formation
of quick-moving thunderstorms, which are currently producing a few
lightning strikes over the waters before dissipating shortly after.
As such, introduced thunder in today`s forecast, with higher
likelihood to occur in the early morning and late afternoon hours, so
use caution when setting up barbecues outside. Dropped rip current
risk to low along north facing reefs as northerly swell appears to
have weakened sufficiently enough at this time; however, another
pulse of northerly swell produced by distant synoptic systems is
expected to arrive by the weekend.

&&

.Eastern Micronesia Update...
Due to the development of much more intense showers near Kosrae,
introduced possibility for locally heavy showers in today`s forecast.
Otherwise, the forecast remains unchanged; cycles of on-and-off
showers and some thunderstorms over the next few days will be
followed by a resurgence in the ITCZ as features embedded within the
aforementioned NET move northward.

&&

.Western Micronesia Update...
The trade-wind troughs gliding across the northern sectors of the NET
have slowed in their forward speed, so delayed showers at Palau to
this afternoon, but upped the showers and introduced thunderstorms to
Yap`s forecast for today. As the convergence zone at the tail-end of
the NET continues to build, showers are likely to be more intense
over Chuuk today, so introduced locally heavy rainfall and higher
gusts in today`s forecast.

&&

.Prev discussion... /issued 1000 PM ChST Wed Nov 26 2025/

.Marianas Synopsis...
Satellite imagery shows partly cloudy skies, while radar imagery
shows isolated showers over the coastal waters. Altimetry shows
combined seas of 6 to 7 feet, while buoy data shows heights around 6
feet.

&&

.Discussion...
A surface to trough is moving through the region, this trough is
producing small, quick moving isolated showers. This showers are
expected to increase as the evening and night progresses, becoming
scattered showers.

For Thanksgiving day through Saturday, expect a fairly dry and
overall pleasant weather pattern. Winds are expected to be around 15
to 20 mph, and any isolated shower that develops is expected to be
short-lived.

Around Saturday night through Tuesday, both the GFS and the ECMWF
models show a broad trough moving into the Marianas. This through is
expected to bring shower into the region. An upper-level high, to
the west of the Marianas, is expect to provide some upper-level
ventilation, increasing the potential for isolated thunderstorms.
Time-heights also reflect this as they show an increase in lift and
moisture across the Marianas.

A pleasant weather is anticipated to return around the middle of next
week.

&&

.Marine...
Moderate trade winds will prevail across the region today,
becoming gentle to moderate thereafter. Combined seas of 6 to 8
feet will gradually decrease by 1 to 2 feet through the rest of
the week, as the elevated trade swell and winds continue to relax.
The east swell as decreased enough to allow the high risk of rip
currents along east facing reefs to end, so there is now a moderate
risk of rip currents along north and east facing reefs, and low risk
on south and west facing reefs. Surf along east facing reefs is
expected to continue to fall over the next several days. A moderate
risk of lightning is anticipated for Saturday through Tuesday as a
broad surface trough is anticipated to move through the islands.

&&

.Eastern Micronesia...
The main item of interests are a surface trough approaching Kosrae
tonight and Pohnpei tomorrow, and several surface troughs in the
trades seen upstream, east of the Date Line. These features will keep
at least scattered showers in the forecast, possibly becoming
numerous from time to time as they pass overhead.

Seas mainly in the 5 to 6 foot range (locally a foot higher for
Majuro`s northern and eastern atolls), look to hold through the end
of the week, possibly increasing a foot for the start of next week.
Pohnpei and Kosrae will see mostly gentle to moderate winds, before
decreasing into the light to gentle range towards the weekend.
Conversely, light to gentle winds at Majuro should become gentle to
moderate by the beginning of next week.

&&

.Western Micronesia...
Visible satellite imagery shows partly cloudy skies and isolated
showers across Palau and most of Yap State as the Near-Equatorial
Trough (NET) remains convectively inactive across the region. This is
likely due to drier air within the region as the Total Precipitable
Water (TPW) satellite product showing TPW values around 1.75 to 2.0
inches at Palau and Yap, while the climatology mean for this time of
year is around 2.08 inches. Across Chuuk State, skies are also
partly cloudy with isolated showers, however an approaching trade-
wind trough, associated with TPW values around 2.10 to 2.4 inches,
is expected to bring mostly cloudy skies and scattered showers to
Chuuk later tonight.

Model guidance suggest transient trade-wind troughs moving through
the region, along with convergent flow north of the NET, will bring
scattered showers to Palau and Yap Thursday. While models support
showers becoming isolated again at Palau Thursday night as the NET
lifts northward, the GFS and ECMWF are now supporting a longer
period of scattered showers at Yap into at least Friday and possibly
into the weekend, with the potential for isolated thunderstorms
increasing Friday as well. For Chuuk, models have remained fairly
consistent with a wet pattern, supported by robust trade-wind troughs
interacting with the NET as it lifts northward. The greatest
potential for scattered showers and isolated thunderstorms will be
Thursday through Friday night, though a period of numerous showers
cannot be ruled out if convection becomes more organized along
convergent flow north of the NET. The potential for showers will then
slightly decrease this weekend and into early next week.

Latest altimetry data indicates combined seas are 4 to 6 feet near
Palau and Yap and 5 to 7 feet near Chuuk. Winds are gentle to
moderate around Palau and Yap, pushing up to fresh at Chuuk, but
winds are expected to decrease Friday as the NET lifts northward
towards the islands. The northeast trade swell will also slowly
subside over the next couple of days, allowing seas heights to drop
a couple of feet, and allow surf to decrease along north and east
facing reefs. Late this weekend and through early next week, a long-
period north swell will move into the region and will build surf
along north-facing reefs by several feet, but wave models suggest
surf will remain below hazardous levels of 9 feet, with seas peaking
around 5 and 6 feet near Palau and Yap and around 7 feet at Chuuk.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&

$$

Regional Overview/Marianas/East and West Micronesia Update: Montvila
Marianas: Bowsher
East Micronesia: Doll
West Micronesia: Schank