427
FXPQ50 PGUM 122011
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
611 AM ChST Thu Nov 13 2025

.Marianas Update...
Satellite shows partly cloudy skies with isolated showers over the
Marianas Waters. The inherited forecast looked good to go so no
changes were needed. The one thing to note is just past the extended,
which will likely enter the extended forecast in this afternoon`s
package, on Thursday and Friday next week we get a 60 percent chance
of exceeding WindSpeed criteria for Small Craft Advisory, and about a
70 percent chance of exceeding WaveHeight criteria, thanks to a
trade-wind surge, which is probably our first encounter with the
coming season, the one I nickname Winder.

&&

.Tropical Systems...
The convection associated with Invest Area 91W has never been all
that great, and now it looks even more ragged. With a dearth of model
support and little to hang your hat on in ASCAT, the Joint Typhoon
Warning Center has closed Invest Area 91W. If something wild happens,
it could always respawn as Invest Area 92W, but at this time that
seems highly unlikely.

&&

.Eastern Micronesia Update...
Some minor changes for Eastern Micronesia based on satellite trends.
While they`re both scattered, the chance of rain was raised from 30
percent to 50 percent for Pohnpei. It was lowered from 40 percent to
20 percent for Kosrae, which took it from scattered to isolated. At
Majuro, it was slightly lowered from 30 percent to 20 percent, which
also made it isolated instead of scattered.

&&

.Western Micronesia Update...
Converging flow into the north side of what was Invest Area 91W is
still causing scattered showers for Palau and Yap. Chuuk will likely
see scattered showers as well, although rain amounts will be a bit
lower, at least for the morning for sure. The inherited forecast
reflected this fairly well, so no changes were needed.

&&

.Prev discussion... /issued 444 PM ChST Wed Nov 12 2025/

Marianas Synopsis...
Satellite imagery show mostly sunny skies with fast-moving isolated
showers over the region. Altimetry shows combined seas of 5 to 6
feet, while buoy data shows seas heights of 4 to 5 feet.

Discussion...
Pleasant weather is expected for the Marianas with partly cloudy
skies and short-lived fast-moving isolated showers for the remainder
of the week. There is a trough to the east past the 150 meridian
that may bring the chance of showers up a notch over the weekend,
however timing and intensity are still in flux. Winds are expected to
be 10 to 15 mph through Thursday night. The winds are expected to
build to 15 to 20 mph for weekend and beginning of next week.

Marine...
Gentle to moderate trade winds are expected to prevail through
Thursday night, and will become fresh for the weekend and beginning
of next week. Combined seas of 5 to 6 feet will gradually subside
over the next couple of days, before building again near the end of
the week. Seas should increase to between 6 and 7 feet Friday into
the weekend. Winds may approach the wind criteria for small craft
advisory, however, at this time are expected to remain below the 22
knot limit. A moderate risk of rip currents is expected along west,
north, and east facing reefs of the Marianas through tonight. As
various swells (trade swell, northerly swell, westerly swell) begin
to diminish, surf will drop enough to allow the rip current risk to
become low, first along west facing reefs Thursday, then along north
facing reefs Thursday night. Surf along east facing reefs may
increase as the trade swell builds by a foot or two over the weekend.

Tropical Systems...
The Joint Typhoon Warning Center has designated Invest 91W, which is
currently located near 4N141E. Invest 91W is currently rated sub-low,
which means significant development into a tropical cyclone is not
expected. Invest 91W is currently bringing scattered to numerous
showers and isolated thunderstorms to Palau and Yap. Little to no
additional impacts are expected for Palau and Yap at this time.

For more information please see JTWC bulletin ABPW10.

Eastern Micronesia...
Things have diminished somewhat today convectively, with a trough
moving through Pohnpei producing scattered showers, with just
isolated showers elsewhere. This should be short-lived though, as a
new trough is crossing the Date Line, with additional troughs in the
trades east of there. Additionally, the models show the center axis
of the ITCZ (Inter-Tropical Convergence Zone) will settle south. This
all points to increasing rainfall potential for the latter half of
the week and into the weekend area-wide, as the troughs move from
east to west. Each one of these features will also allow light to
gentle winds to briefly increase, then diminish after trough passage.

Speaking of those winds, as just stated winds will be light to gentle
after trough passage, briefly becoming gentle to moderate as the
troughs approach/move overhead. In a similar manner, seas may
increase a foot via wind wave increases as the troughs pass,
decreasing a foot or so thereafter.

Western Micronesia...
Scattered to numerous showers are seen across Palau and Yap this
afternoon with isolated showers present across Chuuk. Altimetry data
shows combined seas between 4 and 6 feet across Palau and Yap, and
between 5 and 7 feet across Chuuk.

The main change with this package was the previous buffer
circulation being designated Invest 91W by the Joint Typhoon Warning
Center. Overall, there weren`t many changes with the forecast.
Numerous showers are ongoing across Palau and are expected to
continue tonight. There may be a brief lull of isolated to scattered
showers late this evening, but shower coverage is expected to become
numerous again before midnight. Scattered showers are also expected
for Yap tonight where trade-wind convergence is interacting with the
broad circulation that is Invest 91W. Over the next few days,
scattered showers are expected for both Palau and Yap as Invest 91W
slowly drifts west-northwest. Further development of Invest 91W into
a more organized tropical disturbance is not expected at this time. A
drying trend is expected for Palau and Yap in the wake of Invest 91W
late this weekend and into next week.

Isolated showers are currently present across Chuuk, but will become
scattered overnight. Trade-wind convergence and trade-wind troughs
look to keep scattered showers around for Chuuk through much of the
forecast period.

No changes were made to the marine forecast. Benign sea conditions
are present across western Micronesia with 4 to 6 ft combined seas
across Palau and Yap, and 5 to 7 ft seas across Chuuk. A trade-wind
swell could impact portions of Chuuk State early next week, which
could bring choppy seas to Weno and outlying islands.

&&

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

$$


Marianas/East and West Micronesia/Tropical Update: Stanko
Marianas: Bowsher
East Micronesia: Doll
West Micronesia/Tropical: Williams