853
FXPQ50 PGUM 262019
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
619 AM ChST Sun Apr 27 2025

.Marianas Update...
There was little to change in this forecast package. A weak passing
trough brought a few showers through the area yesterday evening, but
overall conditions remain mostly dry and quiet. Current radar reveals
only small isolated showers crossing Marianas coastal waters early
this morning, and PWATs average about 2 inches across the area.
CIMSS MIMIC TPW imagery reveals a slightly drier environment east of
the islands, and only isolated showers are expected through the
forecast period at this time.

Gentle to moderate trades are expected across the region for much of
the week. Latest buoy and altimetry data indicate combined seas of
around 4 to 6 feet around the Marianas, which are expected to
continue through at least Monday night before tapering down a foot
or two through midweek. A moderate risk of rip currents is expected
to continue along north and east facing reefs through at least the
next few days.

&&

.Fire weather...
0.16 inches of rain fell at the Guam International Airport yesterday
evening as a weak trough moved through, and there has been no
wetting rainfall of 0.20 inches or greater within the last week. This
allowed the KBDI to continue increasing with today`s reading at 685,
which remains in the high category. Gentle to moderate trade winds
will continue with occasional fresh gusts in the afternoon, and are
expected to remain below critical Red Flag criteria. However, fire
danger remains elevated, especially at higher terrain where stronger
winds are expected. Afternoon relative humidity values will continue
to fall near or below 60 percent. A wetting rain is not expected in
the next few days and the KBDI will likely continue to climb.

&&

.Eastern Micronesia Update...
Not much change in Eastern Micronesia early this morning. Pohnpei and
Kosrae are setting up for a rather wet week, with scattered shower
coverage through next Saturday, with Majuro somewhat less so, with
scattered shower coverage only lasting through Tuesday night. Both
Pohnpei and Kosrae also have winds of 15 to 20 mph today which
subside to between 10 and 15 mph tonight. Subsiding trade winds are
often a feature of this time of year, we will have to see just how
far the trend goes. Meanwhile the 15 to 20 mph winds at Majuro remain
in place through at least Tuesday, maybe even into Thursday.

Majuro Waters can expect 10 to 15 knot trades through Thursday, then
they could drop a bit. Seas will be 5 to 7 feet through the week.
Kosrae Waters will receive 5 to 15 knot trades through Thursday, then
they could diminish a little more. Seas will be 5 to 7 feet through
Monday night then could diminish to between 4 and 6 feet. Pohnpei
Waters will get 10 to 15 knot winds through tonight, then 5 to 15
knot winds through Thursday. Seas will be 5 to 7 feet at first, then
diminish to between 4 and 6 feet on Monday.

&&

.Western Micronesia Update...
Also not much change in Western Micronesia early this morning.
Western Micronesia is generally looking at a wet week ahead. The only
possible exception is Yap, and they have only one short period of
isolated, most likely on Tuesday. All of Western Micronesia is
looking at winds of 5 to 15 mph will be all through the period, with
Chuuk having the strongest winds and Koror having the least, but they
all fit into that range.

Chuuk Waters will have winds of 5 to 10 knots, and seas of 3 to 5
feet. Yap Waters will get winds of 5 to 15 knots (5 to 10 after
today), and seas of 3 to 5 feet. Koror Waters will receive winds of
5 to 15 knots (5 to 10 after today), and seas of 2 to 4 feet. Pretty
benign, and pretty likely to stay that way.

&&

.Prev discussion... /issued 507 PM ChST Sat Apr 26 2025/

Marianas Synopsis...
Gentle to moderate trades prevail. Satellite imagery and Doppler
Radar indicate a minor trough moving in upstream. Buoys indicate seas
are about 5 feet.

Discussion...
A minor surface trough upstream is expected to bring low-end
scattered showers across the region tonight, followed by an extended
period of drier trades that may last much of the forecast period.

Marine...
Combined seas of 4 to 6 feet are expected through at least Monday
night, before tapering down a foot or two thereafter. A moderate risk
of rip currents is expected along north and east facing reefs for at
least the next several days. Existing surf is expected to persist
for much of the week as the secondary north swell weakens, but trade
swell strengthens slightly in the second half of the week.

Fire weather...
So far today, a trace of rain has fallen since midnight, with no
significant rainfall expected until midnight. As such, the KBDI is
expected to increase further, which is at 680 currently (high
category). A minor trough will bringer higher rainfall amounts
tonight, but not likely to be wetting rains, so the KBDI may continue
to creep upwards. Even so, winds are expected to remain gentle to
moderate, so conditions critical to fire weather are not expected at
least over the next few days.

Eastern Micronesia...
Model guidance still favors a strengthening trade-wind pattern
developing across the region with a series of weak trade-wind troughs
traversing the band of convergence. Latest satellite data does show
increasing showers and a couple of thunderstorms for Pohnpei, while
Kosrae and Majuro remain relatively clear. The area of convection
extends southwest from near Pohnpei to near 2N150E, along a band of
convergence that is evident on the latest ASCAT analysis. The
increasing convection over Pohnpei is associated with a weak trade-
wind trough interacting with the eastern end of this band of
convergence. Farther east, another weak band of convergence is
evident on satellite extending southwest from the Date Line near 6N
to around 2N171E. Here, a more robust trough, just east of the Date
Line, is interacting with the convergence to produce enhanced
convection well east of Majuro. This trough will continue to move
toward the Marshalls, dragging the convergence farther north.
Scattered showers and a few thunderstorms will move into Majuro early
Sunday morning. The 2 bands of convergence look to link up with the
assistance of the weak troughs moving through, increasing convection
over all three locations Sunday night. Kosrae and Pohnpei should see
the highest POPs (Probability of Precipitation) Tuesday and Tuesday
night, with convection beginning to wane by Thursday. For Majuro, a
drier pattern looks to move into the Marshalls a bit earlier, with a
dry pattern returning around midweek.

Little change is expected for the marine forecast, with mostly gentle
to moderate winds through the coming week. Pohnpei and Kosrae will
see occasional light winds over the next couple of days. Seas will be
at or below 6 feet for Pohnpei and Kosrae, 7 feet for Majuro. The
northeast swell remains low enough that hazardous surf conditions are
no longer possible at either Pohnpei or Kosrae.

Western Micronesia...
A Near-Equatorial Trough (NET) will become increasingly active over
the next several days. JTWC is monitoring an elongated circulation
within the NET, located near 5N130E and still rated sub-low. Multi-
model consensus continues to show a track towards the Philippines.
However, another disturbance is taking shape farther east along the
NET, roughly near 2N144E. This is creating some unsettled weather for
eastern Yap State with models showing a line of showers passing
across Yap Proper tonight. Although model guidance supports a more
active NET, overall organization of showers has shuffled around in
recent model runs. Continue to expect a trend towards a wetter
pattern for Yap and Palau as the active NET pattern shifts northward
in the coming days. Depending on the development of the disturbance
in southeastern Yap State, this may affect the timing and intensity
of showers for the Yap and Palau forecast points. Further details to
the forecast, as far as potentials for gusts or locally heavy
showers, may be added in later forecast cycles and possibly an
issuance of a Special Weather Statement depending on an improved
model consensus. For Chuuk, moderate convergence behind the
disturbance in southeastern Yap State is expected to maintain
scattered to numerous showers and isolated thunderstorms over the
next day or two, then a northward shift of the NET and possibly
further development of the nearby disturbance will also increase
convergence across central Micronesia through the middle of next
week, maintaining scattered to numerous showers across Chuuk.

Benign marine conditions continue over the next several days with
combined seas of 3 to 5 feet expected. Longer-period north swell
continues to move across the region through Monday, which could
generate moderate surf along north-facing reefs, primarily for Chuuk.
Neither seas nor surf are expected to reach hazardous levels at this
time. Winds are expected to be gentle to moderate, but fresh gusts
are possible with the unsettled weather pattern developing in far
western Micronesia late weekend and early next week.

&&

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

$$

Marianas Update: DeCou
East/West Micronesia Update: Stanko
Marianas: Montvila
East Micronesia: Kleeschulte
West Micronesia: Cruz