529
FXPQ50 PGUM 200633
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
433 PM ChST Sun Apr 20 2025

.Marianas Synopsis...
A dry trade-wind pattern will continue to be the main weather
pattern across the Marianas, with satellite imagery showing a weak
trade-wind trough slowly approaching from the east. Winds are fairly
gentle with only the occasional gust reported at the airports within
the Marianas. Altimetry and buoy data show seas are around 3 to 5
feet this afternoon.

&&

.Discussion...
Satellite imagery shows a weak trade-wind trough slowly moving
towards the Marianas, producing scattered showers that look to be
fairly modest in intensity as infrared satellite imagery shows cloud
top temps around 8C to 12C, suggesting showers are fairly shallow.
Tracking the showers via satellite suggests the trough will arrive to
the region Monday morning, which matches fairly well with hi-res
model guidance. This trough will start to exit the region Monday
night, decreasing showers to isolated at Saipan and Tinian, while
scattered showers are expected to linger slightly longer around Guam
and Rota. Otherwise, a seasonally dry trade-wind pattern will
continue for the rest of the week.

&&

.Marine...
According to the latest altimetry and buoy data, seas are around 3
to 5 feet this afternoon. Seas are expected to drop slightly to
between 3 and 4 feet by Wednesday as the trade swell and very weak
north to northeast secondary swell subside slightly. The risk of rip
currents is moderate along east facing reefs, and low along all other
reefs.

&&

.Fire weather...
As of 4 PM today, only a trace of rain fell at the Guam International
Airport. The KBDI is currently at 648 and is expected to increase as
rainfall totals for the day are expected to remain below 0.20 inches
by midnight, remaining in the high category for fire danger. There
is a weak trough that is expected to bring some scattered showers to
Guam Monday, but these showers look to be fairly modest in intensity,
so not expecting much of an impact on the KBDI. Winds the past
couple of days have been around 10 to 15 mph across Guam, and are
expected to change very little through the rest of the week, which
should keep the fire danger from becoming very high as winds remain
below 20 mph.

&&

.Eastern Micronesia...
An unsettled pattern is now in place across eastern Micronesia. The
band of trade-wind convergence that was present across the region
yesterday has fractured a bit and is no longer connected up to
western Micronesia. Convergence is evident from southwest of Kosrae
across Majuro. This convergence is generating increased convection
over the Marshalls, across Kosrae and into southeast Pohnpei State.
Meanwhile, a trade-wind trough is seen just east of Kosrae and is
interacting with the convergence to produce numerous showers and
isolated thunderstorms across Kosrae to south of Kwajalein. This
trough looks to slowly push west over the next couple of days. With
the convergence remaining over the area, the interaction between the
trough and convergence is expected to keep enhanced convection across
Kosrae through at least Sunday night. Therefore, increased showers to
numerous, with isolated thunderstorms across Kosrae through Monday
night. As the trough moves west, it looks to bring increased showers
to Pohnpei as well, though coverage will not be as high as it will be
in Kosrae. This is due to the band of convergence remaining farther
south, with the heavier showers moving through south of Pohnpei. An
overall wet pattern looks to remain over Kosrae and Pohnpei through
the coming weekend. For Majuro, convergence over the atoll is
generating scattered showers and isolated thunderstorms there this
afternoon. The band looks to remain over the atoll through most of
the week, though tonight and Monday look to be the time frame for the
greatest convection. The convergence will gradually weaken through
the week, allowing a drier pattern to move into Friday through the
weekend.

No big changes for the marine forecast. Combined seas of 4 to 6 feet
for Pohnpei and Kosrae, with 5 to 7 feet at Majuro, will continue to
slowly subside over the next few days. Seas are expected to reach 3
to 5 feet for Pohnpei and Kosrae and 4 to 6 feet for Majuro around
midweek and then remain at those levels. Gentle to moderate trade
winds will continue through the week.

&&

.Western Micronesia...
The Near-Equatorial Trough (NET) is the primary weather maker in
western Micronesia over the next several days. The proximity of the
convergence zone just upstream from the NET will keep higher-end
showers and some thunderstorms developing over Palau tonight, with
some heavier showers carrying strong gusts. The shower coverage will
taper down slightly but remain on-and-off in nature over Palau for
much of the forecast period. Yap, on the other hand, will encounter
an extended drier cycle, with only low-end scattered showers expected
tonight. A diffusive trade-wind pattern over Chuuk will remain as
such through Tuesday, followed by periods of patchy showers until the
next weekend.

Combined seas of 4 to 6 feet across the region, are expected to drop
another foot or two by the second half of the week, as trade swell
and wind waves diminish.

&&

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

$$

Marianas: Schank
East Micronesia: Kleeschulte
West Micronesia: Montvila