028
AXPQ20 PGUM 250011
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1011 AM ChST Mon Aug 25 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...

MONSOON TROUGH...
The monsoon trough extends east from a broad, weak circulation,
Invest 93W, crossing 130E near 9N, to another broad, weak
circulation centered west of Weno, Chuuk near 9N147E. Weak
convergence south of the trough is interacting with strong upper-
level divergence to generate widespread showers and scattered
thunderstorms near 130E. Farther east, scattered showers and
isolated thunderstorms are along and south of the trough to just west
of Weno. The circulation west of Weno will continue to drift west,
pulling the monsoon trough west with it. Otherwise, the trough looks
to remain quasi-stationary with little change in intensity over the
next couple of days.

TRADE-WIND AND SURFACE TROUGHS...
A surface trough extends eastward from a weak circulation centered
near 9N147E (described in Monsoon Trough section) to end near 9N155E.
Convergence along this trough is generating scattered showers and
isolated thunderstorms north of Weno to northwest of Pohnpei. This
trough will continue to move northwest over the coming days with
little change in intensity.

A trade-wind trough is found north of the previously mentioned
circulation, extending north-northeast from near 10N149E to end near
20N150E. Convergence associated with the trough is interacting with
a broad area of upper-level divergence to produce scattered to
numerous showers east of the Marianas from north of Weno to
northeast of Saipan. This trough will continue to move west over the
coming days and is expected to strengthen slightly as it approaches
the Marianas.

A series of three weak trade-wind troughs are interacting with the
developing ITCZ. The first one is found just east of Pohnpei,
extending north-northeast from near 4N160E to end near 10N162E,
producing numerous showers and isolated thunderstorms over Pohnpei.
The next one is found just east of Kosrae, extending north from near
2N165E to end near 9N165E. Numerous showers and isolated
thunderstorms are present across Kosrae northward to 10N. The last
trough found just east of Majuro, extending north-northeast from
near 4N172E to end near 11N174E. Scattered to numerous showers and
isolated thunderstorms are found north of Majuro, just east of
Kwajalein. These troughs will continue to move west with little
change in intensity over the next few days.

TRADE-WIND SURGE...
The trade-wind surge has weakened considerably and relocated east of
the Date Line, with strongest winds down to around 15 knots west of
180.

TUTT...
The TUTT enters the region near 25N135E, extending east-southeast to
a cell centered near 19N159E, then turns northeast to beyond 25N
near 161E. A broad area of divergence south of the TUTT from 137E to
the TUTT cell is enhancing convection over a large area from 137E to
east of the Marianas at 153E. Scattered to numerous showers and
isolated thunderstorms are found across this area. Numerous showers
and scattered thunderstorms are found with the TUTT cell west of Wake
Island. The TUTT and TUTT cell are expected to drift west with
little change in intensity over the next few days.

A weak upper-level ridge developed northeast of Wake Island
that has induced another weak branch of the TUTT extending northeast
from near 15N170E to beyond the Date Line near 22N. Only spotty
showers and a couple thunderstorms are found along this weak TUTT.
this branch of the TUTT is expected to remain quasi-stationary as it
slowly strengthens over the next couple of days.

OTHER SYSTEMS...
A weak circulation is centered near 25N153E, with a trough extending
south-southwest from the center to end near 22N151E. Scattered
showers and thunderstorms are found with this system. The circulation
and trough are expected to drift east with no change in intensity
over the next few days.

...ITCZ...
The ITCZ stretches west from 7N180 passing just north of Majuro and
just south of Kwajalein. It continues westward across Kosrae and
Pohnpei, ending northwest of Pohnpei near 10N155E. Scattered showers
and isolated thunderstorms are seen along the ITCZ, except where
trade-wind troughs are interacting with the boundary. These
interactions are described in the Trade-wind and Surface Trough
section above.

$$

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