509
FXPQ50 PGUM 192047
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
647 AM ChST Mon May 20 2024

.Marianas Synopsis...
Satellite imagery is showing partly cloudy skies with isolated
showers for the Marianas. Latest altimetry data is indicating seas
of 6 to 8 feet in the coastal waters.

&&

.Discussion...
Mainly isolated trade showers expected through tonight. Scattered
showers associated with a trade surge look to skirt north of Saipan
this morning. A tropical disturbance (Invest 93W) well south of the
Marianas continues to drift west over the coming days. Multiple
trade troughs and surges will pass through the Marianas as well.
Moisture and convergent flow will creep north beginning on Tuesday,
with scattered showers and isolated thunderstorms expected for Guam
and Rota through Wednesday night. Scattered showers and isolated
thunderstorms are possible for Tinian and Saipan on Tuesday night,
but the bulk of activity looks to stay south. With the surges passing
through, daytime winds could be gusty.

&&

.Marine/Surf...
A trade-wind surge and an elevated trade swell will move through the
Marianas through Wednesday, peaking on Tuesday. Winds will be
moderate to fresh, with combined seas of 6 to 9 feet expected. Winds
and seas may approach Small Craft criteria on Tuesday, but for now
look to remain below thresholds.

The trade swell and surf along east facing reefs have increased, and
a high risk of rip currents is expected through Wednesday. A
moderate risk looks to continue along north facing reefs.

&&

.Fire Weather...
A wetting rainfall of 0.24 inches fell yesterday at the Guam
airport, but the KBDI still rose to 561; in the high category. Today
will be hot with gusty winds during the afternoon, but the minimum
relative humidly is expected to stay above 60%. There will be an
increased chance for a wetting rain beginning Tuesday.

&&

.Tropical Systems...
The Special Weather Statement for western Micronesia remains in
effect. JTWC Invest 93W, centered near 5N141E, remains sub-low and
disorganized. Showers and thunderstorms have persisted across the
eastern half of the broad circulation, across much of Chuuk State and
eastern Yap State. Scattered diurnal showers were more prevalent
across the western half of the circulation impacting Palau and Yap
Proper. Model guidance continues to show drifting 93W west-
northwestward towards Yap and Palau and slowly becoming better
organized, but the threat for development into a significant tropical
cyclone before passing through Yap and Palau has lowered. Those in
Chuuk and Yap States, and the Republic of Palau should continue to
monitor forecasts for future updates.

&&

.Eastern Micronesia...
Not a lot has changed since last discussion. The weak Inter-
Tropical Convergence Zone (ITCZ) stretches through Majuro, Wotje,
Kwajalein, Ailinglaplap regions of RMI and southwestward to Kosrae.
Then the ITCZ crosses into western Micronesia. Showers are expected
along this axis line, however in a state of decay and will continue
to cycle throughout the day. This axis is anticipated to move
westward and will arrive in Pohnpei in the next day or so.

Altimetry shows seas between 5 and 7 feet across eastern Micronesia,
with slightly higher seas to the north. Expect seas to slowly subside
over the next few days, reaching 4 to 6 feet at the end of the week.
Winds will be generally moderate with fresh gusts.

&&

.Western Micronesia...
The forecast for Western Micronesia has aged rather well. The main
concern still remain the near-equatorial trough with a embedded
Invest 93W. Yap and Palau are in the drier section of the intake
region of 93W. A weaker convergence zone has set up just south of
Palau, however, this is not likely to have much effect for Palau. The
difficult part on this system is will 93W westward or will it fizzle
out. Current models suggest it will move westward and bring showers
to Yap, and later Palau, where it is sorely needed. Showers looks to
be building in around tomorrow for Yap and about a day later for
Palau.

Chuuk is in a very interesting conundrum, currently they are situated
on the eastern flank of 93W. The ITCZ and 93W are converging
together across Chuuk state. Probabilities were increased to
numerous for today and tonight to reflect what is shown on satellite
imagery. Showers are expected to remain for Weno so long as 93W and
the ITCZ continue to merge in their region.

Altimetry shows seas of 4 to 7 feet across Yap and Chuuk, with 2 to
4 feet near Palau. Seas look to remain at these levels through the
week. Winds generally moderate with fresh gusts at Chuuk, with
gentle to moderate winds for Yap, and generally gentle winds at
Palau. Winds and seas could be higher for Yap and Palau if 93W
strengthens sufficiently before passage, although that is not
likely.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through Wednesday afternoon for GUZ001.

MP...High Rip Current Risk through Wednesday afternoon for MPZ001>003.

Marianas Waters...None.

&&

$$

Marianas: Slagle
Tropical: Slagle
Micronesia: Bowsher