637
FXPQ50 PGUM 071752
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
352 AM ChST Tue Apr 8 2025

.Marianas Update...
There was little change to the forecast as a mild, dry trade-wind
pattern continues. Radar imagery reveals isolated light showers in
the area, mainly to the southeast of Guam coastal waters and west of
Guam and Rota waters, moving away. CIMMS MIMIC Total Precipitable
Water (TPW) values range 1.3 to 1.5 inches across the Marianas, still
quite dry for the tropics. Shower chances were limited to Guam and
Rota for today, as hi-res model and satellite trends indicate
marginally better moisture and shower potential to the south with a
subtle trade disturbance crossing the area. Mostly sunny skies could
see a brief interruption in the form of a light shower, late in the
morning to the early afternoon. Skies are then expected to remain
mostly clear overnight, with only isolated showers in the forecast
thereafter.

Nearby fixed buoys and SOFAR drifting buoys indicate combined seas
of 4 to 6 feet in the area, which are expected to trend downward by a
foot or two through the middle of the week. Trade winds will remain
mostly gentle through midweek, increasing to moderate speeds around
Thursday.

&&

.Fire weather...
No rain fell at the Guam International Airport yesterday. The KBDI
continues to rise with today`s reading at 666, which is in the high
category. Winds continue to follow a slight decreasing trend, but
fire danger remains elevated. This is especially true for higher
terrain, where stronger winds can be expected. Relative humidity is
expected to remain above 60 percent as dewpoints gradually increase
this week, and critical (Red Flag) fire weather conditions do not
look to be reached for the time being. However, a wetting rain is
not expected for the next several days, and the KDBI is expected to
continue to rise.

&&

.Eastern Micronesia Update...
A relatively drier pattern remains in place across the region as
compared to the wetter trade-wind pattern that surged across the
region bringing heavy rainfall to a number of locations,
particularly to Pohnpei and Majuro. Showers and thunderstorms are
pushing westward across the Date Line along and south of 6N and could
come close enough to Majuro for isolated thunderstorms today through
Wednesday. A broad upper-level trough is generating showers and
thunderstorms farther north, near Enewetak, Bikini and northeast of
Utirik.

Weather southeast of Majuro will continue westward, bringing more
showers to Kosrae around midweek. Otherwise, expect generally fair
and pleasant weather across the region into the weekend.

&&

.Western Micronesia Update...
Weno, Chuuk sits just northeast of showers and thunderstorms that
extend south and westward across the western FSM. Weno is within the
drier trade pattern that`ll slowly build westward. Farther west, an
unsettled weather pattern persists, with a surface trough and
embedded weak circulation pushing across Yap State. Overnight IR
imagery shows the weak circulation pushing overhead of Sorol, and now
sits just east of Yap Proper. Another weak circulation is found
southeast of Koror. The circulation will reach Yap today, bringing
showers and a few thunderstorms to the main island, with a drier
pattern resuming by Wednesday and through the weekend. A wetter
pattern with more showers, will persist across Palau into the
weekend.

&&

.Prev discussion... /issued 557 PM ChST Mon Apr 7 2025/

Marianas Synopsis...
Satellite imagery and radar show partly cloudy skies with hardly any
showers in the Marianas Waters. The buoys reveal combined seas of 4
to 6 feet, composed mainly of east swell, decaying north swell, and
wind waves.

Discussion...
A dry season trade-wind regime remains entrenched in the Marianas.
Light to gentle trade winds will continue the next few days, then
become gentle to moderate. Showers will remain at isolated or slight
chance levels for at least the next several days. This should allow
the Keetch-Byram drought index to continue climbing, it`s expected to
reach 666 Tuesday, and could reach 700 next week, out of a maximum of
800.

Marine...
Moderate seas and mainly gentle winds will make for benign marine
conditions throughout the Marianas Waters this week. Anyone who has
been waiting for a gentler turn in the weather, it doesn`t get much
better than this.

Fire weather...
The drought index is creeping higher, but at least in the short term
the danger is not that high. Humidities are increasing a bit, and
wind speeds will remain subdued. If the wind speeds rise again
though, and the drought index hasn`t been put back in it`s place, we
may have a future issue to deal with. That will be our focus for now
in fire weather, is to try to identify if and when this future issue
may suddenly burst on the scene.

Eastern Micronesia...
A dry trade-wind pattern remains entrenched across eastern Micronesia
with little change expected in this pattern through the weekend.
There is a weak band of convergence that is currently south of 4N,
with a couple of weak trade-wind troughs expected to move through the
region, also mainly south of 4N. A couple of the weak troughs,
currently near and east of the Date Line look to move through south
of Majuro, but could bring enough instability to the region to
produce a couple of thunderstorms near Majuro Tuesday into Wednesday.
The strongest of these troughs looks to clip Kosrae Wednesday,
bringing a short period of low-end scattered showers, possibly a
thunderstorm, to the island. By Wednesday night, the dry pattern will
return to Kosrae. Otherwise, dry conditions will prevail through the
weekend.

No changes from previous forecasts for the marine environment. Seas
look to remain at or below 7 feet for Kosrae and Pohnpei. Seas will
be around 8 feet tonight at Majuro, dropping to between 5 and 7 feet
by midweek. Gentle to moderate winds are expected across the region,
with occasional fresh winds possible at Pohnpei near the end of the
week into the weekend.

Western Micronesia...
A trade-wind trough is still moving through Yap State and is still
east of Yap Proper and Palau, so showers are still isolated at both
locations. This trough is expected to begin reaching Yap Tuesday
afternoon and Palau Tuesday night, increasing showers to scattered
with the potential for some isolated thunderstorms. As this trough
moves off to the west, drier weather is expected at Yap for the later
half of the week and into the weekend. For Palau, modles still show
a near-equatorial trough (NET) developing within the region,
interacting with a the trade-wind trough in eastern Yap State, which
will help to continue scattered showers and isolated thunderstorms
through most of the week. As the NET moves out of the region this
weekend, expected a slightly drier pattern across Palau, but weak
trade-wind troughs will bring brief periods of scattered showers as
they pass nearby. Drier weather is moving into Chuuk Lagoon and
should spread across the state, especially north of 5N. Models
continue to support a fairly dry pattern for Chuuk through the rest
of the week and through the weekend.

Combined seas are still around 4 to 6 feet near Palau and Yap, and
around 5 to 7 feet across Chuuk State. Seas are should drop a foot
or two as the northeast swell weakens slightly Wednesday. Winds are
also expected to remain mostly gentle to moderate for the next
several days.

&&

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

$$

Marianas Update: DeCou
East/West Micronesia Update: Aydlett
Marianas: Stanko
East Micronesia: Kleeschulte
West Micronesia: Schank