191
AXPQ20 PGUM 310018
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1018 AM ChST Sat May 31 2025

Tropical Weather Discussion for the Western North Pacific between
the Equator and 25N from 130E to 180. The following information is
based on recent satellite imagery/data, weather observations, radar,
and meteorological analysis.

...SPECIAL FEATURES...

None.

...OTHER WEATHER SYSTEMS...

TRADE-WIND TROUGHS...
There are several trade-wind troughs now evident across the region.
The first is found just west of Palau, extending north-northwest
from near EQ136E to near 11N132E. Scattered showers and a few
thunderstorms are evident with this trough to the south through
southwest of Palau. This trough will continue west, moving out of the
region within the next 24 hours.

The next trough is found well south of Guam, close to Eauripik,
extending north from near 1N144E to 10N143E. Scattered and numerous
showers and isolated thunderstorms are found near and south of
Eauripik. The trough will continue westward over the coming days,
spreading convection into southern Yap State and eventually into
Palau.

The third trough is found just a bit farther east of the previous
trough, extending north-northeast from near EQ147E to 5N149E. the
trough is enhancing convection south of Ifalik and Satawal,
producing scattered to numerous showers. This trough looks to
continue westward as well, possibly merging with the previous trough
over the next 24 hours.

Another trough is seen just east of Pohnpei, extending north from
near 1N160E to 8N160E. Convergence associated with the trough is
producing scattered showers and a few thunderstorms from northeast of
Pohnpei, across the main island to south of Sapwuafik. The trough and
associated convection will continue westward over the next few days.

Another trough is found east of the Marshalls near the Date Line. It
extends northeast from near 2N178E, across the Date Line to end near
7N178W. The trough is interacting with a developing ITCZ to generate
numerous showers and scattered thunderstorms along and west of the
trough. The trough will continue west, traversing the ITCZ, to bring
increased convection to the Marshall Islands over the next day or
two. This includes Majuro.

Another active trade-wind trough is found to the east of the
Marianas, extending northeast from near 9N145E to near 18N154E. The
northern portion of the trough, north of 13N, is interacting with the
TUTT to produce scattered showers and isolated thunderstorms east of
the CNMI. Spotty showers and a couple of thunderstorms are seen with
the southern portion of the trough. The trough will continue to move
toward the Marianas, bringing increased convection to the islands
over the next couple of days.

The last trade-wind trough is seen a little farther east of the
Marianas, stretching north-northeast from near 9N156E to near
15N158E. The trough is also interacting with the leading edge of a
weak trade-wind surge to generate scattered showers and isolated
thunderstorms between 10N and 15N from 153E to 160E. The trough will
continue moving west, toward Guam, over the next few days. As it
moves away from the retreating trade surge, convection is expected to
decrease as well.

TRADE-WIND SURGE...
A weak trade-wind surge associated with a moderate area of high
pressure moving through to the north of 25N is generating a band of
convection north of the northern Marshall Islands to north of Chuuk
and Pohnpei. The surge extends west from the Date Line to near 155E,
between 10N and 15N. Convection is being enhanced along the western
portion of the surge due to interaction with a trade-wind trough. The
surge will continue to retreat eastward as the high pressure system
responsible progresses east.

TUTT...
The TUTT extends west-southwest across the Date Line near 23N to a
TUTT cell centered south of Minamitorishima near 20N155E, then
continues southwest to beyond 130E near 5N. Divergence associated
with the TUTT is interacting with a trade-wind trough, enhancing
convection to the east of the Marianas. The TUTT and associated cell
will remain quasi-stationary over the next several days.

OTHER SYSTEMS...
A cold front extends southwest through the northwest corner of the
region, crossing 25N near 140E and continuing to beyond 130E near
17N. Cloudiness with patchy showers are found northwest of the front,
with a line of showers and thunderstorms along and just east of the
front. The front will continue to move east over the coming days.

...ITCZ...
An ITCZ extends westward, crossing the Date Line near 5N, to end
near 6N160E. Areas of scattered to numerous showers and isolated
thunderstorms are found south of the Marshall Islands to Kosrae.
Convection is being enhanced near the Date Line due to the
interaction with a trade-wind trough moving through. The ITCZ is
expected to strengthen westward over the coming days and drift north
as trade-wind troughs traverse the area.

$$

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