027
AXPQ20 PGUM 090121
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1121 AM ChST Wed Jul 9 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 of Tropical Storm Danas north of
Taiwan, entering the Area of Responsibility (AOR) near 22N130E,
continuing towards JTWC`s Invest 91W located near 23N138E and then
extending eastward to about 21N145E. Modest west to southwest
monsoon flow is occurring generally west and southwest of the
Marianas extending across and well south of Palau and Yap State. The
active monsoonal pattern looks to continue through tomorrow before a
brief breakdown in monsoonal flow occurs as Invest 91W moves
generally northwestward. The monsoonal flow is expected to return
this weekend with a potential surge near Palau.

SURFACE TROUGHS...
There are a couple surface troughs across the region. The first is a
sharp trough between Pohnpei and Kosrae extending from 5N159E to
13N160E. This trough is producing numerous showers just east of
Kosrae where surface convergence and 20 to 25 kt winds are noted on
last night`s ASCAT analysis. This feature will move westward
bringing active weather for Pohnpei and Chuuk over the next couple
of days as the trough amplifies.

A sharp trough is seen just west and southwest of the Marianas
extending from 12N140E to 16N142E. A weak circulation appears to be
embedded within this trough where the monsoon flow and southeasterly
flow converge. Scattered to numerous showers and isolated
thunderstorms have been developing along this trough this morning.
This feature will move northward over the coming days and will
potentially merge with Invest 91W as the pattern shifts to the
northwest.

TUTT...
The TUTT extends west across the Date Line at around 25N to an upper-
level low centered northwest of Wake Island near 23N164E, then
continues west-northwest through 25N154E. Another upper-level low
exists to the west of Weno, Chuuk at around 7N147E with a trough
extending to the north-northeast to around 16N151E, and another
trough stretching southeast to around 5N150E. The two upper lows are
somewhat disconnected from one other, separated by an upper-level
ridge extending southward over Chuuk Lagoon. The TUTT northwest of
Wake Island is interacting with a series of surface troughs to
produce scattered showers and isolated thunderstorms across the
region, focused to the north and southwest of Wake. This upper-level
low looks to shift northwest over the next few days before
dissipating this weekend, as the TUTT itself looks to rebuild
westward over Wake from across the Date Line. The upper-level low
west of Chuuk Lagoon will diminish over the next few days as it
meanders westward into Yap State.

ITCZ...
A disorganized band of convection associated with a weakly-defined
ITCZ is seen across eastern Micronesia, extending westward from
across the Date Line roughly along 5N. Scattered showers and isolated
thunderstorms are seen over the southern RMI to the south of Majuro
extending to just east of Kosrae. The ITCZ looks to remain weak and
indistinct through the remainder of the week.

$$

Williams/DeCou