629
FXPQ50 PGUM 090818
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
618 PM ChST Sat Nov 9 2024

.Marianas Synopsis...
Latest satellite and radar imagery and showing partly cloudy skies
and isolated showers. Increasing clouds and showers approaching from
the southeast as Invest 94W approaches. Nearby buoys are indicating
seas of 4 to 6 feet.

&&

.Discussion...
The trade trough that brought scattered showers earlier today has
shifted west of the Marianas. Isolated trade showers expected for
tonight through tomorrow morning. A tropical disturbance, known as
Invest 94W from the Joint Typhoon Warning Center (JTWC), continues to
slowly develop southwest of Chuuk, centered near 6.5N and 149.5E.
This system will trek northwestward and approach the Marianas on
Sunday. The latest forecast model guidance has trended the passage of
94W further south of Guam Sunday night into Monday, possibly as a
Tropical Depression. Gusty winds and locally heavy rainfall
potentially causing flash flooding are possible, mainly across Guam
and Rota. In addition, Tropical Depression 25W (TD 25W) has developed
northwest of the Marshall Islands and could pass through the
Marianas later Tuesday into Wednesday, with another round of gusty
winds and heavy rain possible.

&&

.Marine/Surf...
Combined seas of 4 to 6 feet and moderate winds expected through
tonight. Seas and winds begin to increase tomorrow as a tropical
disturbance (Invest 94W) approaches from Chuuk State. Winds and seas
could become hazardous to small craft, especially for Guam and Rota
waters as 94W looks to pass south of the coastal waters. Winds and
seas begin to decrease beginning Monday night, but TD 25W northwest
of the Marshall Islands approaches from the east and could impact the
coastal waters beginning Tuesday night.

A moderate risk of rip currents will continue along north and
especially east facing reefs as the elevated trade swell continues. A
low risk of rip currents is expected along south and west facing
reefs. Surf and rip risk could rise beginning Sunday night as Invest
94W approaches, bumping up swell and wind waves.

&&

.Tropical Systems...
Three tropical disturbances still remain within the Area of
Responsibility (AOR). Invest 93W has been upgraded to Tropical
Depression 25W (TD 25W) by the Joint Typhoon Warning Center (JTWC).
TD 25W is currently centered near 14.1N 159.0E and is moving
northwest, away from the RMI. For more information on TD 25W, see
bulletins issued by JTWC under WMO headers WTPN32 PGTW.

Invest 92W, currently centered near 14.5N 133.2E, continues to move
west toward the northern Philippines. 92W has strengthened and has
become much better organized today, and JTWC and has upgraded it to
a Tropical Cyclone Formation Alert (TCFA). This means 92W is expected
to become a significant tropical cyclone (Tropical Depression) in 12
to 24 hours from now. For more information on Invest 92W, see
bulletins issued by JTWC under WMO headers WTPN22 PGTW.

Invest 94W is currently centered southwest of Chuuk near 6.5N 149.5E
and is moving northwest across Chuuk State toward the Marianas. 94W
remains fairly disorganized at this time, with a "low" rating by
JTWC. This means development into a tropical cyclone is unlikely
within 24 hours. For more information on Invest 94W, see bulletins
issued by JTWC under WMO header ABPW10 PGTW.

&&

.Eastern Micronesia...
Invest 94W has developed into Tropical Depression 25W, however, 25W
is now far enough northwest of Enewetak Atoll so that the threat
from heavy showers, gusty winds, and choppy seas has diminished
across the northwestern RMI. West Pohnpei State is still seeing some
activity associated from Invest 94W, roughly centered south of Chuuk.
Although, only scattered showers are farther east over Pohnpei this
evening, soon to become isolated overnight as 94W continues moving
northwest. Meanwhile, a trough on the leading edge of an Inter-
Tropical Convergence Zone (ITCZ) is moving through Majuro, leading to
scattered to numerous showers and isolated thunderstorms over Majuro
through at least Sunday, with winds becoming fresh at times. Then,
the ITCZ builds into Kosrae Monday and Pohnpei Monday night or
Tuesday. Model guidance indicates a fragmented ITCZ pattern for the
remainder of the week, keeping scattered showers in forecast.

Kosrae and Pohnpei buoys now showing seas around 5 feet this
afternoon. Combined seas are closer to 6 to 7 feet near Majuro. An
increase in trade winds and swell are expected to boost seas an
additional one to two feet over the next couple days, especially
near Majuro where fresh to strong gusts accompany heavier showers
passing through, creating choppy seas at times. Combine seas then
subside to 4 to 6 feet for the remainder of the week in response to a
decrease in trade winds and swell.

&&

.Western Micronesia...
Satellite reveals quiet conditions across much of far western
Micronesia, with spotty shower coverage across the Republic of Palau
and scattered showers near Yap Proper, associated with trailing
surface convergence southeast of JTWC`s Invest 92W. To the east,
numerous showers and isolated thunderstorms are seen spread across
much of Chuuk State extending into parts of far eastern Yap State,
associated with Invest 94W. 94W will be the primary weather concern
over western Micronesia for the coming days, but it will remain
broad, disorganized and sluggish for the remainder of the weekend.
The system will begin to organize in more earnest late Sunday night
and Monday as it shifts northwest over eastern Yap State, to the
south of the Marianas. With latest model trends, 94W could
potentially reach tropical storm strength (maximum sustained winds >
33 knots) sometime late Monday night or Tuesday as it tracks to the
north of Yap Proper. ECMWF develops 94W more quickly, keeping the
track further north where unsettled weather will be felt more
strongly across the southern Marianas with much lighter winds and
shower coverage near Yap, but the latest GFS track places the center
of 94W closer to Yap Proper, which would bring more locally heavy
showers and stronger gusts across the area. Tuesday onward, 94W looks
to move away from western Micronesia, strengthening as it moves over
the Philippine Sea.

Marine conditions remain fairly benign. Babeldaob buoy shows
combined seas of 2 to 4 feet near Palau, and SOFAR buoy data over
southern Chuuk State shows 3 to 5 foot seas. Seas will be choppier
near Chuuk for tonight and Sunday as 94W moves northwest past Chuuk
Proper, owing to locally heavy showers and associated gusty winds.

&&

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

&&

$$

Marianas/Tropical: Slagle
Micronesia: Cruz/Decou