000
FXPQ50 PGUM 292044
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
644 AM ChST Sat Sep 30 2023

.Marianas Synopsis...Satellite and radar showing mostly cloudy skies
with mainly isolated showers this morning. Latest altimetry and Ipan
buoy indicating seas of 3 to 5 feet.

&&

.Discussion...
Expecting scattered showers today, especially for Tinian and Saipan
with enhanced convergence as the monsoon trough lifts north and west
as newly formed Tropical Depression (TD) 14W Koinu pulls away. Light
south to southeast winds could result in showers and thunderstorms
developing over the higher terrain of the islands and drifting north
and west. Decrease in shower coverage tonight as subtle ridging
drifts in. Another round of scattered showers and isolated
thunderstorms for tomorrow as surface trough approaches from the east
as trade wind pattern returns. For the beginning of next week,
isolated to low-end scattered trade showers expected. Deterministic
and some ensemble guidance continues to indicate a potential tropical
system developing near eastern Micronesia and lifting northwest
towards the Marianas, although model spread and uncertainty on
intensity and location is still large this far out.

&&

.Marine...
Combined seas of 4 to 6 feet composed of mixed southwest and east
swells. Seas may rise a foot or two mid to late next week as the east
swell increases. Winds generally light to gentle, but could become
moderate on Sunday with an increase in the trades. A moderate risk of
rip currents will continue for east, south and west facing reefs.

&&

.Tropical Systems...
Invest Area 93W is now TD 14W Koinu near 16N132E, well north and
west of the Marianas, Yap and Palau, moving to the west at 10 kt. 14W
is expected to develop into a Tropical Storm by Sunday evening and
then a typhoon early next week as it encounters favorable candidness
to strengthen as it drifts north and west through the Philippine Sea
away from our area of responsibility. For additional information,
please see the bulletin issued by the Joint Typhoon Warning Center
under WMO header WTPN31 PGTW and by National Weather Service Guam
under WMO header WTPQ31 PGUM.

Former Invest 94W has dissipated for the time being but an area of
deep convection within a broad circulation centered between Kosrae
and Majuro. Deterministic and some ensemble members are still
indicating a tropical disturbance developing near Pohnpei early next
week and drifting northwest towards the Marianas, although model
spread and uncertainty on intensity and location is still large this
far out.

&&

.Eastern Micronesia and Chuuk...
Active weather is seen over Kosrae and Majuro and is currently
moving into Pohnpei. A trade-wind trough extends from Chuuk to
Majuro, models show some subsidence aloft over Chuuk so expecting
isolated showers for this morning for Chuuk. The trade-wind trough
is expected to weaken as it makes its way to Pohnpei but will still
bring an uptick in showers. Maintained the low-end scattered showers
for Pohnpei today and kept the same numerous and occasional showers
for Majuro and Kosrae. Models have been hinting at a circulation
developing near Chuuk and crossing the Marianas mid-week next week.

Latest Altimetry indicates 5 to 7 feet near Majuro and 4 to 6 feet
near Pohnpei and Kosrae. Wave models indicate a small decrease in
wave heights the next few days.

&&

.Western Micronesia for Yap and Palau...
Similar weather pattern continues for Palau and Yap. Tropical
Depression 14W, and the gusty winds affecting Yap and Palau, are
slowly peeling away. There are still pockets of stronger winds, but
is less than 25 kt, latest ASCAT shows.

Altimetry`s latest pass shows seas of around 5 to 6 feet near Palau.
Seas are expected to decrease a bit the next day or two as gusty
westerly winds weaken. Expect long period swell from the northwest
sometime next week as 14W moves further away.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...

GU...None.
MP...None.
Marianas Waters...None.

&&

$$

Marianas: Slagle
Tropical: Slagle
Micronesia: Hong