488
FXPQ50 PGUM 021842
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
442 AM ChST Fri Jan 3 2025

.Marianas Update...
Only the most minor of changes were needed to the forecast tonight.
The main concerns remain the incoming north to northeast swell for
the weekend. This swell may bring hazardous conditions in regards to
surf and increasing the risk of rip currents. Weatherwise, expect
fair conditions with isolated showers that may pop up near the
diurnal maxima.

&&
.Eastern Micronesia Update...
Only minor changes were needed, mainly to increase rainfall
potential slightly at Pohnpei as a trough is moving through (it`s
subtle/weak though), aided by a long-advertised but little ITCZ
(Inter-Tropical Convergence Zone) that`s trying to develop in a west-
northwest to east-southeast orientation between 5N and 7N from 142E
to south of Pohnpei, before dipping west and south of Kosrae, before
turning east near 3N to 4N as it stretched to the Date Line.

Tonight/this morning is the "most" active the ITCZ has been in a
while. The question is...is this just a nocturnal "flare-up"...or
actual ITCZ development? Time will tell, as the models have been way
overdone for days in their forecast solutions, as the previous shift
alluded to.

&&

.Western Micronesia Update...
Little change was done as the main thing to watch is a subtle
surface trough that bisects Koror from Ngulu. We kept showers
isolated for the next 24 hours across Koror and the rest of Palau,
but this trough will need to be watched given the recent pulsing
attempts of convection southeast of Koror.

The other notable change was to increase rainfall potential at Chuuk
during the next 24 hours, bringing in high-end scattered coverage
today and bumping up numerous wording to tonight, continuing into
tomorrow (which was in the previous forecast - numerous coverage for
Saturday). This was based on satellite and model streamline trends,
with some semblance of an ITCZ trying to develop just to the south
of Chuuk, at least for now. Otherwise, remaining changes were
minimal.

&&

.Prev discussion... /issued 356 PM ChST Thu Jan 2 2025/

Marianas Synopsis...
Moderate diffusive trades prevail across the region. Tanapag buoy
indicates seas are about 4 to 5 feet.

Discussion...
Various high pressure cells moving across the northern Pacific are
inducing drier, diffusive trades across the Marianas. Periods of
clear skies are expected throughout the forecast period. The pressure
gradient between the tropics and mid-latitudes is expected to induce
breezy conditions toward the end of the week.

Marine...
Combined seas of 5 to 7 feet are expected to increase slowly the
next several days, as trade swell strengthens and another long-period
north swell makes its way across the region. These increasing swells
may produce hazardous surf and high rip current risk along north
facing reefs by late Saturday or Sunday. Sea conditions may become
hazardous to small craft sometime early next week. A moderate risk of
rip currents is expected along west, north, and east facing reefs
for the next few days.

Eastern Micronesia...
The Inter-Tropical Convergence Zone (ITCZ) continues to fall apart,
resulting in less shower coverage than in previous forecasts. The
models over the past couple of weeks have been much more aggressive
with ITCZ development and strength than what actually occurred.
Therefore, based on past performance and available satellite data,
significantly decreased shower coverage and probabilities over the
next week. Model guidance continues to indicate numerous to
widespread showers with isolated thunderstorms across the region.
However, decided to limit POPs (Probability of Precipitation) to
around 40 percent, which is mid-range scattered/chance. There may be
short periods of numerous showers as weak trade-wind troughs move
through, though location and timing for this will be difficult. Late
in the weekend into early next week, a dry trade-wind pattern looks
to establish itself across the region, resulting in only a slight
chance of showers through most of next week.

Combined seas look to remain at or below 8 feet for the next several
days at Pohnpei and Kosrae, with Majuro getting up to 9 feet. The
trade swell is quickly being replaced as the primary swell by a north
swell produced by a strong, distant northern latitude storm. This
swell is currently forecast to reach up to 6 feet, though it isn`t
out of the question for it to build a bit higher. If it does reach 7
feet or more, a High Surf Advisory may be needed for north facing
reefs of all three islands. Winds look to be mostly gentle to
moderate for Pohnpei and Kosrae into the weekend. Then, winds are
expected to become occasionally fresh. For Majuro, moderate to fresh
winds are expected through at least Tuesday next week.

Western Micronesia...
A fairly quiet pattern prevails across western Micronesia, as the
Near-Equatorial Trough (NET) remains far south of Palau and Yap, and
most showers in the region are the result of shallow troughing or
localized surface convergence. Several weak troughs within the trade
flow north of the NET axis are producing scattered showers near Yap,
Chuuk, and Koror, but coverage is spotty across much of the region.
There is a weak circulation within the NET located south of Koror near
3N135E, and scattered to numerous showers can be seen spreading
across its vicinity near the equator and over the far outer
Indonesian islands. Showers increase over the next few days, mainly
for Palau and Chuuk as an ITCZ fragment strengthens over Chuuk State
and shifts westward, while the NET lifts north toward Koror. This
will lead to a wetter pattern this coming weekend into the first half
of next week.

Combined seas and surf have continued their downward trend with
diminished trade swells and northerly swells, and seas should remain
at around 4 to 6 feet through the end of the week. Combined seas and
surf look to increase this weekend into early next week as pulses of
a larger northerly well begin to push through the region, initially
for Chuuk around Saturday, and later for Yap and Palau Sunday night
into Monday. Winds will be moderate to occasionally fresh throughout
the forecast period.

&&

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

$$

Marianas: Bowsher
East/West Micronesia: Doll