676
FXPQ50 PGUM 260749
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
549 PM ChST Wed Jun 26 2024

.Marianas Synopsis...
Partly cloudy skies and isolated showers are seen across the Marianas
this evening with some short-lived thunderstorms passing to the north
of Saipan and south of Guam. A band of more widespread showers and
thunderstorms is present south of Guam stretching east to west
between 8N and 12N. Northeast of Saipan, an upper-level low is slowly
heading northwest and is centered near 19N151E. Ritidian buoy shows
seas of 6 to 7 feet.

&&

.Discussion...
The latest forecast maintains a drier, trade-wind dominant outlook
for the next several days, but with the inclusion of a slight chance
of thunderstorms for tonight and Thursday. Upper-level westerlies are
seen in today`s upper-air sounding around 40 kft, and are providing
some strong shear, courtesy the upper low soon to pass by to the
north. While most showers in the region have been relatively shallow,
failing to reach above 30 kft, some have been just strong enough to
reach up to around 45 kft to produce some lightning before being
sheared apart. For this reason, felt it prudent to add the slight
possibility for a thunderstorm to briefly pop up closer to the
islands.

Noting the convection farther to the south, satellite trends the past
several hours have shown a slight northward spread, so will need to
watch that overnight. Latest model guidance shows an overall westward
trend to the convection with little significant northward spread.

Winds will decrease over the weekend becoming gentle by early next
week reflecting a trend that will also be seen over much of
Micronesia.

&&

.Marine...
Combined seas will hover between 5 and 7 feet the next couple of days
before beginning to subside Friday. Over the weekend, seas are
expected to settle between 4 and 5 feet. This will still maintain a
moderate risk of rip currents along east facing reefs, but the risk
should drop to low along north facing reefs around Friday.

&&

.Eastern Micronesia...
Not much happening across eastern Micronesia this afternoon. Latest
satellite data only shows isolated showers from Kosrae to the
Marshall Islands. Farther east, over Pohnpei, a trade-wind trough is
seen approaching Pohnpei, with a band of trade-wind convergence
stretching from Chuuk into Pohnpei. These features will maintain low-
end scattered showers through tonight. The trough looks to move west
into Chuuk State by Thursday, however, the band of convergence will
linger over Pohnpei, keeping scattered showers through Thursday
night. By the end of the week, model guidance consensus shows an ITCZ
moving back into eastern Micronesia, bringing increased convection
to the region for the remainder of the forecast. POPs (Probability of
Precipitation) look to increase to 30 to 40 percent by Saturday, and
to around 50 percent, increasing further to around 50 percent over
the weekend.

Marine conditions don`t look to change much over the coming days.
General to moderate trade winds look to become gentle over the
weekend. Combined seas of 4 to 6 feet are seen across the region.
Seas are expected to remain at these levels at Majuro through the
weekend. However, seas look to subside a bit at Pohnpei and Kosrae,
dropping to 4 to 5 feet at Pohnpei over the weekend and 3 to 5 feet
at Kosrae.

&&

.Western Micronesia...
A broad disturbance is seen near Mindanao with a Near-Equatorial
Trough (NET) extending eastward toward Palau. To the east of the
northern end of the trough, a band of trade-wind convergence extends
eastward from Yap Proper across Chuuk State into eastern Micronesia.
These features have been responsible for very strong deep convection
over the past couple of days, especially at Palau. The disturbance
and band of convergence will continue to drift westward, with the
NET moving out of the region by Thursday afternoon. The interaction
between these two features will continue to produce high-end
scattered showers and isolated thunderstorms across Yap and Palau
tonight, with coverage decreasing Thursday as the NET disturbance and
NET drift farther west, away from Palau. The band of convergence,
however, looks to remain over the area a bit longer. This is
expected to keep POPs around 30 percent at Palau, and around 40
percent at Yap through Thursday night. By Friday, models indicate
that another weak disturbance will develop to the southeast of Palau,
with a NET developing across the area. Models are in fairly good
agreement that this will occur, however, they do differ on location.
This system is expected to increase moisture, and in turn,
convection, across the region. Maintained POPs around 50 percent for
now, as the actual location remains a mystery. This could change as
the location becomes more evident.

Farther east, Chuuk can expect increasing convection through the
evening as a weak trade-wind trough moves out of Pohnpei into Chuuk.
This will bring scattered showers to Weno later this evening. There
will also be a risk of thunderstorms due to weak upper-level
divergence being over the state. By the end of the week, the
developing NET that is expected to be over Palau and Yap looks to
extend eastward into Chuuk State as well. This will maintain an
overall unsettled pattern for Weno through the middle of next week,
with POPs remaining around 40 percent through next Wednesday.

Yap and Palau buoys show seas near 5 feet this afternoon, while seas
remain around 4 to 6 feet at Chuuk. Combined seas are expected to
slowly subside over the next several days, reaching 2 to 4 feet at
Palau by the end of the week at Palau and over the weekend at Yap.
Seas are expected to drop to between 2 and 4 feet at Weno by the
beginning of next week. Mostly light to gentle winds are expected at
Palau and Chuuk through the end of the week, then become mostly
gentle. Moderate to fresh winds at Yap are expected to subside over
the next couple of days, becoming light to gentle over the weekend.

&&

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

$$

Marianas: Aydlett
Micronesia: Kleeschulte