409
AXPQ20 PGUM 280140
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1140 AM ChST Mon Sep 28 2026

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...

TROPICAL AND MONSOON DISTURBANCES...
A developing disturbance, Invest 93W, is found along the monsoon
trough, centered well E of the Marianas, NNE of Weno, Chuuk, near
13.7N 154.8E. 93W is moving slowly WNW. There is an active
convective pattern associated with Invest 93W, with scattered to
numerous showers and isolated thunderstorms found over a broad area
from 150E to 157E from 9N to 16N. Invest 93W is expected to slowly
strengthen as it moves WNW to NW over the next few days, possibly
passing N of Saipan, moving through the northern CNMI. Residents of
the Marianas, especially Tinian, Saipan and the northern CNMI should
monitor forecasts for any changes to expected development and
movement.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The monsoon trough enters the region near 13N130E, stretching E
through a weak circulation centered W of Guam near 13N143E, through
Invest 93W to another weak circulation centered N of Kwajalein near
14N168E. The trough then turns SE to cross the Date Line near 8N.
Enhanced convergence and weak surges are producing scattered to
numerous showers from just N of Koror, Palau, across Yap and Ulithi
to NW of Geferut. Another band of showers begins to the SE of
Geferut, stretching ENE to S of Invest 93W, ending NNW of Pohnpei.
Farther E, numerous showers and isolated thunderstorms are found
along and N of the trough and weak circulation centered N of
Kwajalein, with convection becoming isolated E of 172E. The monsoon
trough is expected to remain quasi-stationary over the next few
days, with little change to slight strengthening, especially near
Invest 93W.

SURFACE TROUGHS...
A surface trough is found just W of Kwajalein, extending SSW from the
weak circulation centered near 14N168E to end near 8N167E. Scattered
to numerous showers and isolated thunderstorms are found from
Kwajalein northward to the circulation. This trough will continue to
drift E to NE as it rotates around the circulation, with little
change in intensity.

TRADE-WIND TROUGHS...
An elongated trade-wind trough extends N from near 16N165E to end
just W of Wake Island near 22N166E. Scattered showers are found
along and up to 60 miles each side of the trough. This trough will
continue to move W over the next few days.

OTHER SYSTEMS...
Scattered to numerous showers and isolated thunderstorms are found
over the far NW corner of the Guam Area of Responsibility (AOR) to
the S of STY Surigae, which is located N of the AOR. Surigae is
expected to move ENE, pulling the convection with it, with
convection likely moving out of the Guam AOR within the next couple
of days.

A band of convergence is found S of Minami Torishima along 20N from
151E to 160E. Scattered showers and a few thunderstorms are found
along this band. The convergence is expected to dissipate over the
next couple of days.

Another band of convergence is found W of Invest 93W, extending W
from 13N150E to ENE of Rota near 14N146E. Scattered showers and
isolated thunderstorms are found along this band. This convergence is
expected to strengthen slightly as Invest 93W moves WNW and
strengthens over the coming days.

$$

Kleeschulte