877
FXPQ50 PGUM 170802
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
602 PM ChST Fri Oct 17 2025

.Marianas Synopsis...
Gentle to moderate easterlies prevail across the region. Satellite
imagery and Doppler radar indicate mostly dry and clear conditions
this afternoon. Buoys and altimetry show seas are 5 to 8 feet.

&&

.Discussion...
A moderate to fresh trade-wind regime is expected to ensue by
Saturday, bringing breezy conditions through late Saturday afternoon,
before tapering down slowly thereafter as the pressure gradient
decreases between the tropics and the mid-latitudes. Showers are
expected to remain minimal overnight, followed by periods of patchy
showers and a thunderstorm or two developing during the afternoon
hours, as winds pick up from the east. A few more minor troughs will
make their way across the region for much of next week, bringing
low-end scattered showers as winds continue to weaken.

&&

.Marine...
Combined seas of 6 to 8 feet will stay elevated and choppy through
at least the weekend, as northerly swells and trade swell continue to
mix in, before tapering down by the middle of next week as these
swells weaken. A moderate risk of rip currents is expected along
west, north, and east facing reefs of the Marianas through Saturday,
before becoming low along west facing reefs thereafter. Surf is
expected to remain elevated along north and east facing reefs until
the middle of next week, as the aforementioned swells diminish.

&&

.Eastern Micronesia...
As one trough departs Pohnpei off to the west, attention turns to a
new trough that has crossed the Date Line today. This feature will
continue west the next several days, bringing a brief period of
increased rainfall potential to areas from east to west. Otherwise,
the lack of an ITCZ (Inter-Tropical Convergence Zone) will allow for
just isolated shower coverage aside from when the trough approaches
or passes overhead.

As for winds, they`ll remain light to gentle through the weekend,
increasing into the gentle to moderate range for the first half of
next week. Seas mainly in the 5 to 6 foot range will persist through
the forecast period.

As for surf concerns, a northeasterly swell of 5 feet at 8 seconds
will persist through Saturday for Pohnpei and Kosrae, combining with
a long-period northerly swell of 3 feet at 12 seconds. This will
keep surf elevated in the 7 to 8 foot range for the north facing
reefs. The northeasterly swell will decrease on Sunday. Beyond that,
there are some indications that the northeasterly swell may build
again towards the middle of next week. This is something we`ll keep
an eye on.

&&

.Western Micronesia...
Satellite this afternoon shows scattered showers and isolated
thunderstorms across far western Micronesia, mainly over and
northwest of Palau waters, and west of Yap waters. The area of
convergent inflow into Invest 96W continues to shift westward as the
disturbance itself transits the Philippine Sea, with the center
having already exited just west of Guam`s Area of Responsibility
(AOR). An upper-level trough centered just north-northwest of Palau
and Yap has been providing support to thunderstorms along the tail
end of inflow into 96W, continuing over western Palau waters this
afternoon. Shower and thunderstorm chances diminish over Palau
heading into the weekend as 96W and associated showers move further
away from the area. Yap will continue to see periods of scattered
showers through the weekend as a series of weak trade-wind troughs
propagate west across the region. Early to mid next week, shower
chances for Palau and Yap will increase once more as a weak monsoon-
like pattern begins to set up across the region.

To the east, the broad southwest-northeast oriented trough over Chuuk
has begun to shift northwest of coastal waters. Swaths of mid to
upper level clouds remain extensive across Chuuk State, but showers
have diminished to isolated near Weno, with most of the convergence
and showers focused further north. Quiet conditions will continue
through Sunday, with showers beginning to increase Sunday night
through early next as a broad trough moves into the area.

Latest altimetry data indicates combined seas around 3 to 5 feet
near Palau and Yap and around 4 to 6 feet near Chuuk, comprised of a
primary northeast swell and light north swell. Similar sea
conditions will prevail for much of the forecast period, with light
to moderate trades expected through early next week. Trade winds will
become mostly moderate for Chuuk by midweek.

&&

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

$$

Marianas: Montvila
East Micronesia: Doll
West Micronesia: DeCou