679
FXPQ50 PGUM 200656
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
456 PM ChST Wed Aug 20 2025

.Marianas Synopsis...
Satellite imagery shows mostly cloudy skies across Guam and Rota,
and partly cloudy skies over Tinian and Saipan. Scattered showers
with decent vertical development are moving across Guam, and mainly
over southern Rota waters. Winds are light to gentle with occasional
gusts near showers. Buoys show seas around 3 to 4 feet.

&&

.Discussion...
Convergence in front of a trade-wind trough is expected to bring
scattered showers starting for Guam tonight, then spread farther
north into the CNMI Thursday night and Friday. After this feature
passes to the west, shower coverage may decrease slightly to
isolated over the weekend, then models are showing a bit more
organized convection early next week.

&&

.Marine/Surf...
Combined seas of 3 to 4 feet and light to gentle winds are expected
through the weekend. Easterly trades look to increase to gentle to
moderate early next week. With a fairly weak trade-wind swell of 3
to 4 feet expected to subside a bit more over the weekend, a moderate
risk of rip currents along east-facing reefs may drop to low as
early as Friday or Friday night.

&&

.Tropical Systems...
Invest 90W is near 12N132E, over 300 miles northwest of Palau. 90W
remains a broad and poorly organized tropical disturbance with
flaring convection weakening and becoming more spread out during the
course of the day. There is mid-level cyclonic turning, but based on
today`s scatterometry pass, there is no clear low-level circulation.
There remains a low potential for development into a significant
tropical cyclone within the next 24 hours. Models indicate a
northwestward track, likely exiting our AOR by Thursday.

&&

.Eastern Micronesia...
A subtle trough is crossing Pohnpei along the leading edge of surface
convergence. This area also denotes the leading edge of a wavy ITCZ
building across the region, as it (the ITCZ) stretches from here
east-southeast of Kosrae, then turns northeast from just beyond
(east) of Kosrae to on Majuro`s doorstep, and crosses the Date Line
near 9N. A more pronounced trough extends along the east of Kosrae to
near (just east) of Majuro to Date Line axis.

For Pohnpei, scattered showers tonight will become isolated for
Thursday, before moving in by the weekend. Meanwhile, Kosrae and
Majuro will see scattered showers through the period. Isolated
thunderstorms will also develop area-wide. Seas of 4 to 6 feet will
continue through early next week, with mainly light to gentle winds
prevailing.

&&

.Western Micronesia...
Satellite imagery depicts isolated showers across Yap and Chuuk with
scattered showers across Palau. Altimetry data shows combined seas
between 3 to 5 feet across the region.

A lull in activity is present across western Micronesia with showers
decreasing across Palau tonight and isolated showers present across
Yap and Chuuk. The lull looks to remain short lived as Yap will see
scattered showers from a subtle trough tomorrow, which is forecasted
to merge with a more substantial trough that is moving across
southern Chuuk State. This will bring numerous showers to Palau and
Yap Thursday night into Friday. Guidance continues to show a weak
circulation moving between Yap and Palau later this week. This looks
to enhance shower coverage, but at this time, development into a
more organized system does not appear likely. For Chuuk, low end
(30%) showers are expected towards the end of the week. An increase
in shower activity is expected this weekend as fragments of the ITCZ
move across the region.

No changes were made to the marine forecast. Benign seas of 3 to 5
feet look to continue through the week. Some choppier seas could be
possible under heavier showers at Palau and Yap Thursday night
through Friday night.

&&

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

$$

Marianas: Cruz
East Micronesia: Doll
West Micronesia: Williams