197
FXPQ50 PGUM 240842
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
642 PM ChST Mon Aug 24 2026

.Marianas Synopsis...
Satellite imagery shows isolated showers across the Marianas as a col
begins to drift over the region. Model guidance suggests combined
seas of 7 to 9 feet.

&&

.Discussion...
The Marianas are currently dry as a col produces divergent flow over
the area. However, scattered to numerous showers are visible on
either side of the coastal waters and are expected to move in
sometime late tonight or tomorrow with shower coverage highest over
Guam and Rota. Light to moderate winds tomorrow will trend down by
Wednesday and potentially allow for island effect showers and
thunderstorms to develop. Winds may stay light enough for continued
island effect for Tinian and Saipan Thursday before winds increase
late week and into the weekend as a new monsoonal surge potentially
moves into the Marianas. While a wetter period is expected late this
week with locally heavy showers possible, flooding and mudslide risk
has decreased at this time.

&&

.Marine...
Significant southwesterly swell driven by the monsoon pattern and
Tropical Depression Atsani (19W), well north-northwest of Yap and
west-northwest of the Marianas, along with convectively-driven gusts
will slightly increase seas back to 7 to 10 feet through tonight.
Combined seas are expected to gradually subside to around 5 feet
midweek, then gradually rise back up going into the weekend. Light to
gentle winds tonight are becoming light to moderate Tuesday. An
unsettled, but disorganized monsoon pattern continues to bring
scattered showers and isolated thunderstorms across the Marianas this
week with locally heavy showers possible beginning Friday.

Hazardous surf and dangerous rip currents continue along west-facing
reefs through tonight. So a High Surf Advisory and High Rip Current
Risk Statement have been extended through tonight. Surf will begin to
decrease by tomorrow with the rip current risk likely becoming
moderate for all reefs. There is a moderate risk of lightning for the
next several days starting late tonight.

&&

.Tropical Systems...


Typhoon Saudel (17W) was centered near 24N136E, moving west-northwest
at 18 mph. Maximum sustained winds are 125 mph near the center, with
this intensity persisting overnight. Saudel is expected to continue
on this trajectory toward Okinawa, exiting NWS Guam`s AOR later
tonight.

Newly-named Tropical Depression Atsani (19W) was centered near
16N137E, moving north-northeast at 16 mph. Maximum sustained winds
remain at 35 mph near the center, with this intensity persisting
overnight, remaining a Tropical Depression. Atsani is expected to
pivot to the north, following the favorable environment in the wake
of TY Saudel. This system will slowly but surely disintegrate as it
jets away and opens up into a wave by tomorrow, or potentially
earlier if it loses its surface traction tonight.

For more information on Typhoon Saudel (17W), please refer to the
Tropical Cyclone Warning from JTWC under WMO header WTPN31 PGTW, and
the TC Public Advisory from the National Weather Service under WMO
header WTPQ31 PGUM. For more information on Tropical Depression
Atsani (19W), please refer to the Tropical Cyclone Warning from JTWC
under WMO header WTPN33 PGTW, and the TC Public Advisory from the
National Weather Service under WMO header WTPQ33 PGUM.

&&

.Hydrology...
A reinvigorated monsoon trough with a potential embedded tropical
disturbance that was previously expected to develop and bring periods
of heavy rainfall to the Marianas beginning Wednesday, has continued
to fallen behind. The mid to long-term model guidance continues to
show a downward trend in any potential cyclogenesis, with the
enhanced monsoon pattern now likely to fall apart over the next few
days, pushing back any potential heavy rainfall into the weekend,
potentially even into early next week as the col overhead lingers and
forces diffusive flow. Due to this uncertainty, this will be the last
Hydrologic Outlook issued for this rain event, unless conditions
warrant a new issuance in the coming days.

&&

.Eastern Micronesia...
The forecast remains on track with minimal changes needed. In
general, the monsoon trough stretches from the CNMI in the Marianas
to a broad/weak circulation northeast of Pohnpei, then to near
Kwajalein, extending to north of Majuro and exiting the region at the
Date Line. Good surface convergence near and south of the trough will
maintain scattered shower and isolated thunderstorm potential area-
wide the next few days, possibly longer depending how the trough
reorientates later in the week. Winds will be gentle to moderate for
Pohnpei and Majuro for the next 72 hours, while being lighter at
Kosrae as you are further removed from the trough. Seas of 5 to 7 feet
will continue.

&&

.Western Micronesia...
A gentle to moderate southwesterly monsoon regime is expected to
continue across much of western Micronesia this week, bringing peak
shower and thunder coverage to Chuuk tonight through Tuesday, and to
Yap sometime late Wednesday into Thursday. Palau will remain under a
dry spell as a tropical ridge stays anchored just north of the
Equator and most of the convection sits more north and east of the
area. Conditions will steadily improve at Yap toward the weekend as
diffusive flow moves in, meanwhile Chuuk is expected to see a wetter
pattern continue for much of the week as a monsoonal convergence zone
lingers.

Combined seas of 5 to 7 feet near Palau and Yap, are expected to drop
a foot or two the next several days as southwesterly swells and wind
waves diminish. After, seas are expected to increase once again once
elevated northwesterly swells make it to the region by the weekend.
Combined seas of 4 to 6 feet near Chuuk will decrease by about a
foot in the second half of the week, to then persist for several more
days.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk until 4 PM ChST this afternoon for GUZ001.

     High Surf Advisory until 4 PM ChST this afternoon for GUZ001.

MP...High Rip Current Risk until 4 PM ChST this afternoon for MPZ001>003.

     High Surf Advisory until 4 PM ChST this afternoon for MPZ001>003.

Marianas Waters...Small Craft Advisory until 5 PM ChST this afternoon for PMZ151>154.

&&

$$

Marianas: Ogle
East Micronesia: Doll
West Micronesia/Tropical/Hydrology: Montvila