866
FXPQ50 PGUM 311915
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
515 AM ChST Mon Sep 1 2025

.Marianas Update...
The Marianas are now under partly cloudy skies with isolated
showers, based on radar and satellite. Weather will stay like this
for at least today. Left the forecast alone for now so that it brings
showers back in. At this time though, it looks like the current
forecast could be doing that too fast. That will be the main forecast
problem for the day shift today.

&&

.Eastern Micronesia Update...
Convection has collapsed across much of Eastern Micronesia. The only
feature is a mostly east-west oriented trough left over from a
previous ITCZ. The showers with it are primarily to the north.
However, there are plenty of clouds. So today is a lot of mostly
cloudy with isolated or partly sunny with isolated. Again, it looks
like it will take a couple (or a few) days for the showers to come
fully back to life here.

&&

.Western Micronesia Update...
The shower activity is only doing a little better in Western
Micronesia. There`s been a collapse from Koror eastward and
southward. Yap and Chuuk could possibly be isolated through Tuesday.
Palau is supposed to be scattered through Tuesday, but for now that
looks like an uphill battle. They are active enough though, that
Palau is the only place I have scattered showers today.

&&

.Tropical Systems Update...
Invest Area 95W has moved out of the WFO Guam Area of Responsibility.
Please check the PAGASA bulletins if you would like to keep informed
on what it is doing.

&&

.Prev discussion... /issued 547 PM ChST Sun Aug 31 2025/

Marianas Synopsis...
Satellite imagery shows overcast skies, while the radar shows
shallow isolated showers. Ritidian buoy shows sea heights of near 5
feet. Winds are gentle to moderate with a few fresh gusts.

Discussion...
A shallow surface ridge has set up over the Marianas. This lull will
bring pleasant weather for much of the region tonight and Labor Day.
The next trough will be coming through around Monday night. This
trough may bring scattered to numerous showers and isolated
thunderstorms to the region. Model guidance suggests, this trough
will linger through the middle of the week. Once this trough exits
the region, pleasant weather looks to return.

Marine...
Light to gentle winds are expected over the next few days. Then,
near the middle of the week, winds are anticipated to become light
to moderate and falling back to light to gentle for the weekend.
Combined seas of 3 to 5 feet are expected to gradually fall over the
week to near 3 feet by the weekend. A moderate risk of rip currents
along east facing reefs will persist through Monday. This risk is
expected to drop to low Monday night as the trade winds and swells
continue to weaken. Model guidance suggests surf will be below 5 feet
through the rest of the week. There may be a moderate risk of
lightning for the middle of the week.

Tropical Systems...
A tropical disturbance known as JTWC`s Invest 95W, has no
discernible center of rotation within NWS Guam`s AOR, but the axis
of rotation does enter the region near 12N130E well northwest of
Palau. Moderate to occasionally deep convection is associated with
this feature, producing scattered to numerous showers and scattered
thunderstorms within an extensive secondary trough extending from
said disturbance to the northeast from 12N130E to 18N140E, then
curving due east and ending west-northwest of Agrihan. This feature
is expected to continue to move away from the area, remaining largely
a semi-open trough as it skirts the eastern shores of the
Philippines over the coming days. This system is not likely to
develop into a significant tropical cyclone over the next 24 hours,
and it is not likely to produce any direct impacts on Palau, Yap, or
the Marianas.

Eastern Micronesia...
A lead surface trough that stretches from southeast of Kosrae,
through Kosrae and Kwajalein, then off to the east-northeast is the
main item of interest. This feature has mostly cloudy skies along it,
with widely-scattered showers and an occasional thunderstorm
developing along it. This feature will continue to move west across
the region within the trade flow. Despite an ITCZ being present with
near seasonal levels of moisture, convection has really struggled to
become more widespread during the last 24 hours, with the models
continuing to show this trend continuing through the middle of the
week. Thereafter, the ITCZ looks to become more active with
increasing shower and thunderstorm potential.

Seas will hold in the 3 to 5 foot range for the first half of the
week, possibly increasing a foot by the weekend. Light to gentle
winds will prevail.

Western Micronesia...
Weather conditions have been improving steadily near Palau and Yap as
the aforementioned tropical disturbance Invest 95W continues to move
away from the region to the northwest. This has decreased the pulses
of a southwesterly monsoon surge across Palau and Yap, with gust
potential and shower coverage decreasing overnight at both locations.
Showers will continue to diminish through Tuesday, when the
subtropical ridge and diffusive trades following the lee side of 95W
will bring a brief dry cycle, followed by a return of patchy showers
and some thunderstorms for the rest of the week. At Chuuk, high-end
scattered showers and isolated thunderstorms will diminish
considerably by Monday as the mid-levels dry out, producing a drier
period for much of the week as most of the convection remains well
southeast of Weno, Chuuk.

Combined seas of 4 to 6 feet near Palau and Yap are expected to
decrease 2 to 3 feet over the coming days, as southwesterly winds
and swell decrease and trade swell remains fairly weak. Combined seas
of 3 to 5 feet near Chuuk are expected to remain as such for much of
the forecast period, comprised mainly of an easterly swell.

&&

.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: Montvila