658
FXPQ50 PGUM 121853
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
453 AM ChST Tue Aug 13 2024

.Marianas Update...
Only minor edits to the previous forecast made. Partly cloudy skies
and spotty showers expected today. Did speed up the arrival of a
surface trough and the potential for scattered showers and isolated
thunderstorms for late tonight, based off the latest satellite and
model trends, and continuing through Wednesday night. For late week
into the weekend, expect a chance of showers and slight chance for
thunderstorms as a series of surface troughs pass through the
Marianas.

Combined seas of 3 to 4 feet from mainly northwest swell, and light
to gentle winds prevail through Wednesday morning. Winds and seas
look to rise slightly for mid to late week as the easterly flow
returns and easterly swell becomes dominant. A moderate risk of rip
currents continues along west and north facing reefs through tonight,
becoming low on Wednesday. Surf and rip risk looks to build along
east facing reefs late week as the easterly swell increases

&&

.Tropical Systems Update...
Invest 91W has steadily intensified over the past day and has
developed into a tropical depression (TD 08W), centered near
24N137E. Convection continues to flare up and become better
organized around the low-level disorganized center (LLCC) and
maximum winds estimated to be around 25 kts. TD 08W is expected to
intensify further as it turns northward towards Japan, possibly
becoming a tropical storm by later today and a typhoon by Wednesday
night.

&&

.Eastern Micronesia Update...
Only minor tweaks to the forecast were needed. For Pohnpei, showers
are expected to be isolated in the AM hours, becoming scattered by
the afternoon and overnight. Kosrae is expected to have fair weather
due to being in a weak ridge. Majuro can anticipate a weak trough
passing through later tonight to bring showers up the borderline
between isolated and scattered.

Seas remain fairly benign for the region, with combined seas of 3 to
5 feet. Winds are expected to be light to gentle.

&&

.Western Micronesia Update...
Only minor weeks to the forecast were needed. For Palau, island
effect showers at anticipated for the afternoons due to low winds and
the winds that are there are expected to be blowing long wise across
the island. This gives convection the maximum time to get started.
For Yap, cloud cover was about the only thing needed to be changed,
and the POPS for tonight were also dropped due to the ridge being a
little more prevalent in the models. For Chuuk, the POPs were
increased for tonight and tomorrow, models indicated that the trough
that is bringing Weno showers will linger a bit longer.

Seas remain fairly benign for the region, with combined seas of 2 to
4 feet. Winds are expected to remain light to gentle.

&&

.Prev discussion... /issued 601 PM ChST Mon Aug 12 2024/

Marianas Synopsis...
Light to gentle southeast winds and combined seas of 3 to 4 feet
continue across the region. Satellite indicated isolated showers
across the Marianas coastal waters with only a shallow buildup of
island convective showers.

Discussion...
Very little change to the forecast. The region continues to be fairly
dry and today`s showers were minimal over the island. Winds are
expected to turn a bit more easterly with easterly swell becoming the
predominant swell around Thursday. Light to gentle winds are
expected to continue through the forecast period, but stronger winds
are possible with the development of tropical systems along the
monsoon trough.

Marine/Surf...
No significant changes to the marine forecast. 3 to 4 foot northwest
swell is expected to decrease by 2 feet starting mid week through
the weekend. Starting Wednesday and continuing trough the weekend,
east swell is expected to increase from 2 feet to 3 to 4 feet.
Predominant swell direction is expected to be easterly by Thursday.

Tropical systems...
A Tropical Cyclone Formation Alert (TCFA), Invest 91W, located near
23N136E west of Iwo To, is showing good rotation and increasing
convection near its low-level center. Surface winds are estimated to
be around 18 to 23 knots. Invest 96W, located east of Iwo To, has an
exposed low- level circulation center and convection is not well
organized. Both these systems are expected to track to the north over
the next few days as 95W, which is further north of 96W along the
monsoon trough, heads towards northern Japan.

Eastern Micronesia...
Pohnpei had island-effect showers during the afternoon, as winds
remained weak due to the ridge of high pressure that is extending
through central and western Micronesia. A pair of troughs, one south
of Kosrae and the other moving across the Marshall Islands also
brought scattered showers to Kosrae and Majuro earlier today, but
these troughs are starting to push westward and allowing showers to
become isolated at both locations this evening.

As the ridge slowly weakens and drifts westward, easterly winds are
expected to slowly become gentle to moderate across the region,
however it looks like winds will be weak enough Tuesday for more
island-effect showers over Pohnpei during the afternoon. The trough
south of Kosrae is expected pass south of Pohnpei Tuesday as well
which will help to spread scattered showers into the coastal waters
of Pohnpei, while the trough in the Marshall Islands will move out of
west of the Marshall Islands tonight should pass well north of
Kosrae, keeping showers isolated at Kosrae Majuro through Tuesday.
Another series of troughs is expected to move across the Date line
starting Wednesday which will increase the potential for showers and
thunderstorms across the region for the latter half of the week.

Benign marine conditions are expected this week, with combined seas
mainly around 3 to 5 feet, potentially reaching up to 6 feet at
Kosrae this weekend. The primary swell remains out of the east to
southeast, while light to gentle winds will become gentle to
moderate easterly winds across the region around Wednesday or
Thursday.

Western Micronesia...
A ridge of high pressure stretches across the Marianas into the
region. Weak convergence in the south-southwesterlies will increase
clouds and showers at times, but are still expected to be isolated
to scattered for Yap and Palau. Similar to the past several days, the
light and variable winds will allow for island-effect showers to
develop in the afternoon. After seeing the development of the
afternoon convection over Palau and attributing it to the relatively
larger land mass, added a slight chance of thunderstorms during those
times as well. The ridge is expected to weaken and shift
northwestward, allowing for trade showers to develop at times for Yap
and Palau starting late this week. A weak trade- wind trough is east
of Chuuk and will continue to propagate westward, bringing scattered
showers to Chuuk Tuesday. Chuuk will continue to see periods of
scattered showers through the week and over the weekend with passing
trade-wind troughs.

Benign marine conditions are expected over the next several days,
comprised of light to gentle winds and combined seas 2 to 4 feet.
Seas near Chuuk are expected to build to 5 feet later this week with
increasing trade swell.

&&

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

&&

$$

Marianas: Slagle/Hong
Micronesia: Bowsher/Schank/Cruz