958
FXPQ50 PGUM 251959
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
559 AM ChST Sat Sep 26 2026

.Marianas Update...
Partly sunny skies with isolated showers lie over the Marianas at
this time. Heavier showers lie to the southeast, and seem to slowly
be moving in. Seas of around 3 feet will stay pretty consistent the
next few days, leading to benign marine conditions, which are
extending all the way across Micronesia.

&&

.Eastern Micronesia Update...
Eastern Micronesia does have scattered showers near Pohnpei and over
Majuro, so retained the inherited showers at these two locations. The
showers at Kosrae have faded away, so reduced the showers here to
just isolated in coverage. These updates were made based on satellite
trends.

&&

.Western Micronesia Update...
The leading edge of the showers keeps decaying as it heads into
Chuuk. So took the numerous 70 that was previously forecast today,
and formed it into a scattered 30. The band of monsoon showers is
still holding together this morning, but is less cohesive than
yesterday, and there`s a hole right over Yap right now. Therefore,
took the numerous 70 previously forecast for Yap, and made it into a
scattered 50. Koror Palau just has debris clouds over them at this
time. Looked in the Synoptic Ob Decoder, and they have had zero rain
for three days now. Therefore took the scattered 50 and gave it a
massive haircut down to isolated 20.

&&

.Prev discussion... /issued 549 PM ChST Fri Sep 25 2026/

Marianas Synopsis...
Radar and satellite indicate isolated to scattered showers are over
the Marianas this evening with high cirrus clouds covering much of
the sky. Winds are light and variable as a col remains over the
region. Models, buoys, and spotter reports indicate combined seas of
3 to 4 feet.

Discussion...
While a generally dry period remains through the weekend,
precipitable water remains between 1.75" and 2.25" across all
islands. This moisture is expected to remain along with light and
variable winds, so island effect showers and isolated thunderstorms
will be possible Saturday, Sunday, and Monday. The highest chances
will be for Guam. Light northwesterlies Saturday across Guam may
keep showers more to the southeast. While no thunderstorms were
observed over the islands today, upper-level support looks to
increase slightly the next three days which should help support
thunderstorm development. By Tuesday, westerlies winds ahead of a
slowly developing trough will prevent further island effect showers,
but then bring additional monsoon moisture into the region by
Wednesday. This will bring shower coverage back to scattered with
isolated thunderstorms possible. This trough will be closely
monitored for any potential impacts to the Marianas late next week.

Marine...
Light to variable winds will prevail through the weekend. Seas
around 3 feet will remain small until at least Tuesday before
possibly starting to increase. Swells currently consist of a very
small southwest swell and an east-northeast swell. The risk of rip
currents is currently low along all reefs of the Marianas and is
expected to stay that way through at least Tuesday. Isolated
thunderstorms could drift over the waters during afternoon island
effect convection for the next three days. This will cause a moderate
risk of lightning in the afternoon along the coastlines.

Tropical Systems...
Tropical Storm Surigae (25W) is centered east-northeast of Luzon,
Philippines near 20.2N 130.3E. Surigae is moving northwest at 13
mph. Surigae remains a tropical storm, with maximum sustained winds
of 45 mph. Tropical storm force winds are found only in the northern
half of Surigae. TS Surigae will make a gradual turn toward the
northwest, then north, over the next couple of days, eventually
turning northeast around Sunday night or Monday. It is expected to
move out of the Guam Area of Responsibility (AOR) within the next 6
to 12 hours. Surigae is expected to strengthen a bit over the next
few days as well, possibly becoming a typhoon Saturday night or
Sunday morning.

For more information on TS Surigae, please see bulletins issued by
the Joint Typhoon Warning Center under WMO header WTPN31 PGTW and
from the National Weather Service under WMO header WTPQ31 PGUM.

Eastern Micronesia...
A band of convergence south of the monsoon trough, within the
monsoon flow, will maintain scattered showers and isolated
thunderstorms across Pohnpei and Kosrae for the next couple of days.
This convergence will continue to slowly decrease, allowing a drier
pattern to move into Pohnpei and Kosrae late in the weekend,
continuing dry through the middle of next week. For Majuro, the dry
pattern currently in place will slowly erode through the evening,
with showers and thunderstorms seen to the east of the atoll moving
into the region later tonight, near midnight. Latest guidance keeps
an active pattern across the Marshalls through the weekend and into
next week as the eastern end of the monsoon trough remains over the
area and weak surface trough traverse the boundary.

For the marine forecast, no big changes were made to the inherited
forecast. Mostly light to gentle winds will prevail through the
middle of next week, though Pohnpei can expect occasional moderate
winds for the next couple of days. Benign seas will continue for the
next several days.

Western Micronesia...
Numerous showers and isolated thunderstorms are expected to persist
at Yap through the weekend as a moist, west to southwest monsoonal
flow lingers across the area, before it slowly lifts northward over
the next couple of days. Locally heavy showers are still possible
for Yap, but confidence remains low. Mostly isolated to low-end
scattered showers are expected to continue at Palau through Saturday
night before drier conditions settle in this weekend. Unsettled
weather is developing to the southwest of Chuuk and is expected to
fill over the evening and overnight hours. This will bring numerous
showers and isolated thunderstorms forecast to continue through
Saturday night. Gentle to moderate west to southwest winds will
continue at all sites for the next couple of days with winds easing
slightly this weekend for Palau and Yap. Generally benign marine
conditions are expected to prevail through at least the weekend with
combined seas of 3 to 5 feet expected at all forecast points. Though,
locally choppy seas will be possible near Yap and Chuuk with heavier
showers and thunderstorms.

&&

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

$$


Marianas/East and West Micronesia: Stanko
Marianas: Ogle
East Micronesia: Kleeschulte
West Micronesia: Bowsher