866
FXPQ50 PGUM 302055
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
655 AM ChST Wed May 1 2024

.Overnight Update...

.Marianas...
The main change was to add scattered showers through tonight as a
weak trade-wind trough passes through the region. The KBDI has
reached 312, now in the moderate category. Scattered showers today
provide a chance of a wetting rain and may delay the steady climb in
KBDI. However, by Thursday expect the drier trade wind pattern to
resume, with only passing isolated showers expected. For marine,
added background north swell entering the region this weekend,
boosting surf along north-facing reefs next week, but combined seas
mainly stay in the 4 to 6 foot range.

.Eastern Micronesia...
Little has changed in the eastern Micronesia forecast. Shower
coverage was increased for Kosrae through tonight as various incoming
trade troughs have become much more pronounced on satellite.
Meanwhile, on-and-off shower coverage has been nudged up slightly
but thunderstorms were removed for Majuro`s forecast due to
lackluster time height profiles. Otherwise, the rest of the weather
and marine forecasts remain unchanged.

.Western Micronesia...
The tropical disturbance meandering southeast of Palau has developed
slow-moving cells that now have potential to bring training showers
and thunderstorms to Palau today, with heavy downpours possible. If
the thunderstorm complexes remain in southern waters, Koror might be
spared the brunt of the showers. Even so, model guidance has
indicated higher confidence for an associated convergence zone to
bring more showers Thursday as well. The aforementioned disturbance
is expected to also produce much needed showers over Yap the next few
days, but they are expected to remain low-end scattered in nature.
Otherwise, the weather and marine forecasts remain unchanged.

&&

.Prev discussion... /issued 617 PM ChST Tue Apr 30 2024/

Marianas Synopsis...
Satellite indicates scattered cumulus clouds and very isolated light
showers over the Mariana Islands this afternoon. Upstream, to our
east, the leading edge of a modest trade-wind surge and weak surface
trough has moved to about 15N148E, and is still moving westward.
Local airports report surface winds are gentle to moderate with
occasional fresh gusts. Combined seas nearby are 4 to 6 feet.

Discussion...
The surface trough to our east is causing patchy clouds and isolated
moderate showers. The leading edge is at about 148E, between 13N and
15N, and will arrive later tonight and likely trigger a few moderate
to briefly heavy showers late tonight and early Wednesday for the
local forecast zones. Otherwise, a relatively dry, gentle to moderate
trade-wind flow will continue across the Mariana Islands.

Marine/Surf...
Gentle to moderate trade winds will continue this week. Combined
seas of 4 to 6 feet tonight will slowly subside to 3 to 5 feet by
Friday. There will be a moderate risk of rip currents along east
facing reefs for the next several days, with a low risk expected
along all other reefs. Surf along east facing reefs will subside a
foot or two by Friday.

Fire Weather...
The KBDI is at 292 today, still in the low category. A few showers
can be expected at times in the coming days, especially over the
southern mountains, but wetting rains are unlikely. The KBDI will
likely rise steadily and conditions will continue to dry out.

Eastern Micronesia...
Satellite analysis during the day showed trade-wind convergence south
and east of the Marshalls generating scattered showers and isolated
thunderstorms. Both deterministic and ensemble model members show
trade-wind convergence with weak embedded troughs shifting northward
and over Majuro, Kosrae, and Pohnpei generating scattered showers and
isolated thunderstorms through at least this weekend.

Combined seas of 4 to 6 feet are expected at Kosrae and Pohnpei
through the weekend. For Majuro, combined seas of 6 to 8 feet are
expected through at least Saturday before falling one to two feet.

Mainly moderate trades with some gusts to fresh are expected through
Thursday, then becoming gentle to moderate at Majuro, Kosrae, and
Pohnpei.

Western Micronesia...
A weak surface trough moving over Chuuk State has been generating
scattered showers during the day. The aforementioned weak surface
trough is expected to move westward and impinge into the Near
Equatorial Trough(NET) bringing chances for scattered showers and
isolated thunderstorms to Palau around Thursday. Model analysis
during the day shows that the NET will lift northward sometime over
the next couple of days before retreating again this weekend. The
northward movement of the trough and impinging weak surface troughs
within the trade-wind flow will likely bring scattered showers and
isolated thunderstorms to Palau and perhaps Yap Proper on Wednesday
into Thursday. Afterwards, Yap Proper will be too far north of the
deeper moisture and stronger convergence with only isolated showers
expected through at least the weekend.

Combined seas of 4 to 6 feet are expected through the weekend at
Chuuk, Yap, and Palau. Gentle to moderate winds are expected at Yap
and Palau through this weekend. For Chuuk, mainly moderate trades
with some gusts to fresh are expected through Thursday, then
weakening to gentle to moderate through the weekend.

&&

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

$$

Marianas: Simpson/Cruz
Micronesia: Kelly/Montvila