660
FXPQ50 PGUM 062015
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
615 AM ChST Mon Sep 7 2026

.Marianas Update...
Radar and satellite reveal partly sunny skies and isolated showers
within the Marianas Waters this morning. Copious rain last night has
left the atmosphere a bit tired early this morning. Winds are
somewhat favorable for island convection today. The limiting factor
will be, do we get enough sunlight to reinvigorate the atmosphere?

&&

.Marine...
Starting out with a west swell of around 4 to 5 feet, which by the
end of the period is just 4 feet. It is joined though by a more usual
4 foot east trade-wind swell. That could make the surf forecasts more
interesting, slightly higher surf values along more reefs.

&&

.Eastern Micronesia Update...
No changes were needed for Eastern Micronesia. The showers are about
to arrive for Majuro, and this was shown pretty nicely. Pohnpei and
Kosrae will be rather dry for at least the next 24 hours, and this
was also shown rather well. The forecast might be trying to moisten
Pohnpei and Kosrae a little too quickly, we can evaluate that more
today though. No action was needed overnight.

&&

.Western Micronesia Update...
No changes were needed for Palau or Yap, they`re expected to be dry
for the next 24 hours, and they will be. Had to dry Chuuk out,
satellite shows the showers there are more likely to be isolated than
scattered, so lowered the PoP`s from 40 to 20. How dry is West
Micronesia getting? From my Decoded Synoptic Obs Viewer, I`m
estimating, the last 12 days at Chuuk have seen 1.38 inches. At Yap,
the last 10 days I`m estimating 0.48 inches, and at Koror, Palau,
over the last 14 days, it looks like they had only 0.12 inches. That
would be quite dry.

&&

.Prev discussion... /issued 534 PM ChST Sun Sep 6 2026/

Marianas Synopsis...
Satellite and radar imagery depicts mostly cloudy skies, scattered
showers, and isolated thunderstorms quickly moving across the
region. Combined seas are around 3 to 5 ft.

Discussion...
A nearly-stationary col as well as upper-level divergence has
maintained the convectively active, wet pattern today. After
midnight, a lull in showers and light northerlies may allow for
enough clearing for scattered, island-effect rainfall Monday
afternoon. Due to the slow-moving nature of the convergence zone,
isolated thunderstorms are possible through Monday. Then, drier
conditions are possible for a few subsequent forecast periods as the
active weather pattern exits the region to the northwest. As for the
latter half of the week, northerlies may increase in speed to light
to gentle. Shower coverage may differ as model guidance hints at a
potential circulation developing to the east of the islands. Due to
the high uncertainty regarding this pattern, showers top out at 30
percent through Saturday with a slight chance of thunderstorms
returning. This will continue to be refined as confidence naturally
increases with time. Shortly thereafter, a dry spell is possible
entering early next week.

Marine...
The westerly swell continues to subside, allowing for combined seas
to drop to 3 to 5 ft tonight, followed by another decrease to 3 to 4
ft Monday. Light to gentle northwesterlies will shift to the north
Monday and eventually to the northeast later in the week. There is a
moderate risk of rip currents along north, south, and west facing
reefs, with the former two dropping to a low risk beginning Monday.
Island-effect showers may be a concern Monday afternoon for southern
coastal waters.

Eastern Micronesia...
Very little change to the previous forecast. Maintained isolated
showers at Pohnpei and Kosrae through Monday night. A re-invigorated
monsoon trough is expected to bring increased showers to Majuro
later this evening, ending the dry pattern there. This will initiate
an overall unsettled pattern spreading across eastern Micronesia
that will continue across the Marshalls through the end of the week.
The convection will spread west over the next day, bringing this
pattern to Kosrae and Pohnpei Tuesday. This pattern will then
continue through the end of the week.

No major changes were made to the marine forecast. Seas could climb
to as high as 7 feet after midweek. Light to gentle winds will become
gentle to moderate at Kosrae Monday, then become moderate to fresh
around midweek and remain there through at least Friday. Pohnpei will
see gentle to moderate winds Tuesday that will continue through the
end of the week. For Majuro, winds will become light to moderate
Monday, returning to light to gentle by midweek.

Western Micronesia...
A ridge extending from a buffer circulation near West Papua is still
inducing some diffluent flow over Yap and Palau, leading to quiet
conditions over the next few days. During this period of drier
weather, haze sourced from distant wildfires in Indonesia are
expected to continue across Palau and Yap. Scattered showers and
isolated thunderstorms are found across the far southern islands of
Palau, closer to the buffer circulation, however this area of showers
is not expected to build farther north. A broader area of showers
and a few thunderstorms are spread out across across Chuuk State and
eastern Yap State due to moderate northwesterly convergence alongside
the monsoon trough and a monsoon disturbance between Chuuk and
Pohnpei. The monsoon disturbance is expected to move in a general
west-northwest direction in the coming days and remain fairly
disorganized, however, the strengthening convergence along the
western and southern peripheries will be the focus of unsettled
weather for the region this week. As the disturbance shifts west-
northwestward, scattered showers and isolated thunderstorms are
expected to continue through Monday at Chuuk. Showers then taper down
to isolated to scattered Monday night and Tuesday. As the monsoon
trough reorients itself this week, southwesterly convergence begins
to set up across Chuuk around Wednesday, bringing another increase in
scattered showers and isolated thunderstorms towards the latter half
of week. Overall, Yap and Palau remain on the outskirts of this
developing pattern, but depending on the proximity of the monsoon
trough, low-end scattered showers may return to Yap Wednesday and
Thursday, and to Palau sometime late week.

Latest altimetry data shows combined seas have remain steady at 2 to
4 feet near Palau and Yap, and 3 to 5 feet at Chuuk. Benign marine
conditions are expected to continue over the next several days, with
seas increasing to 4 to 6 feet around Thursday for Chuuk coastal
waters due to an increase in south to southeast swell. Light to
gentle winds persist over the next several days with an increase in
gentle to moderate southwesterly winds at Chuuk starting Wednesday.

&&

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

$$


Marianas/East and West Micronesia Update: Stanko
Marianas: Mesa
East Micronesia: Kleeschulte
West Micronesia: Cruz