453
AXPQ20 PGUM 100003
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1003 AM ChST Fri Oct 10 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 remnants of a weak monsoon-like trough have shifted further west
along the edge of Guam`s Area of Responsibility (AOR), extending
eastward from the southern Philippines through 8N130E, to just
north of Palau around 8N134E. Numerous heavy showers and scattered
thunderstorms are seen along this trough axis, mainly to the east of
Mindanao and northwest of Koror. Surface observations and
scatterometry indicate gentle to moderate southwest to west winds
over Palau, just south of the trough axis. Models indicate this
feature will shift northwest over the next day or two and exit the
region, with little evidence of a monsoon trough returning this next
week.

SURFACE AND TRADE-WIND TROUGHS...
There are several notable surface and trade-wind troughs within the
region. The first is a broad, east-west oriented trough centered just
south of the Marianas, extending eastward from around 13N138E,
passing over Guam coastal waters before curving to the southeast
toward Chuuk Lagoon, ending near 9N150E. Scattered to numerous
showers and isolated thunderstorms are focused along and north of the
trough axis, mainly to the west of Guam and Rota waters where this
feature is interacting with a weaker trough that extends northward,
from 14N141E to 20N141E. Here, divergence aloft associated with an
upper-level low is enhancing convection along the trough axis,
producing scattered thunderstorms northwest of the Marianas. Further
east, a weak, broad trough extends south-southwest across the
northern CNMI, from 23N151E to 15N146E. Showers are isolated to
scattered along and west of the trough axis. These features look to
lift northwest over the next day or two and diminish, maintaining a
wetter pattern for Guam and the CNMI into the weekend.

A weak trade-wind trough is seen over Chuuk State, extending south-
southeast from west of Chuuk Lagoon around 7N151E to southwest of
Nukuoro near 3N154E. Scattered to numerous showers and isolated
thunderstorms are seen within this broad trough, mainly along the
southern extent to the west of Nukuoro and south of Lukunoch. This
trough looks to diminish over the next day as it shifts west,
running up against a surface ridge over eastern Yap State.

TUTT...
The TUTT extends southwest into the AOR from beyond 18N180, passing
through a TUTT low centered to the south of Wake Island near
14N168E, then continues west-southwest to around 8N154E, northeast of
Chuuk. Divergence aloft associated with the TUTT cell south of Wake
is helping to enhance showers and thunderstorms over the northern and
central RMI along an ITCZ fragment, discussed below. The TUTT low
looks to continue westward over the next few days, likely helping to
maintain a wetter pattern across eastern Micronesia this weekend,
before moving over the Marianas early next week.

...ITCZ...
An ITCZ fragment has become more developed over eastern Micronesia,
extending westward from the Date Line around 7N, crossing the
central Marshall Islands just north of Majuro and over Kwajalein,
then meandering to just east of Kosrae near 6N165E. There are
scattered to numerous showers with isolated thunderstorms within this
feature, focused mainly just south of Kwajalein and east of Majuro
this morning. This ITCZ fragment looks to persist in the area for the
next day or so, extending slightly further west to increase showers
near Kosrae, before devolving into a series of weaker troughs
Saturday night through the remainder of the weekend. The ITCZ looks
to briefly become active within the region again during the first
half of next week.

$$

DeCou