227
AXPQ20 PGUM 130121
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1121 AM ChST Sun Jul 13 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...

TROPICAL AND MONSOON DISTURBANCES...
The Joint Typhoon Warning Center has closed Invest 94W, which was
located near 11N141E, due to the lack of organized circulation within
the monsoon trough that extends across the Republic of Palau and Yap
State, producing scattered to numerous showers. More detail on the
monsoon trough and overall pattern is discussed below.

Tropical Storm Nari (06W) is centered just outside of the area near
26N142E. Numerous showers and isolated thunderstorms are found
south to southwest of the center and along the feeder bands leading
into the storm, mainly northwest of the northern Mariana Islands.
Deep convection is seen along one band that extends southwest to near
18N134E, and a second band that extends south to near 16N143E. TS
Nari is expected to move slowly northeast over the next couple of
days, pulling the associated convection and feeder bands with it,
decreasing showers around the Mariana Islands by Monday.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The primary axis of the monsoon trough extends eastward across the
Philippines and enters the region near 13N130E to about 11N140E,
northeast of Yap, and then turns southeast and ends in southern Chuuk
State near 4N154E. Scattered to numerous showers and isolated
thunderstorms are found mainly south of the trough over Palau and
across the outer islands of Yap State, passing south of Yap Proper.
Satellite scatterometer data shows gentle to moderate westerly flow
along the monsoon trough, with embedded gusts near heavier showers
and thunderstorms. The monsoon trough is expected to slowly lift
north to northwest over the next several days, keeping a wet monsoon
pattern across the Republic of Palau and most of Yap State. Model
guidance suggest a broad circulation, potentially a monsoon
depression, developing northwest of Palau and Yap later in the week,
which could increase winds across Palau and Yap, also leading to
higher seas and surf along west facing reefs.

TRADE-WIND TROUGHS...
A subtle trough is currently east of the Marianas near 14N151E,
producing spotty to low-end scattered showers. As this trough moves
near the Marianas it is expected to remain weak and will likely be
hard to distinguish from the monsoon tail that extends from Tropical
Storm Nari (06W).

Satellite imagery shows three trade-wind troughs are embedded within
the ongoing ITCZ across central and eastern Micronesia. The first is
between Chuuk and Pohnpei, extending from 5N153E to 9N157E. The
second is east of Kosrae, extending north-northeast from 2N166E to
near Kwajalein in the Marshall islands near 9N169E. The final trough
is east of Majuro, extending from 3N176E to 9N179E. These troughs are
helping to enhance convection within the ITCZ, producing numerous to
widespread locally heavy showers and isolated thunderstorms along
the troughs. These troughs will continue to progress west over the
coming days, maintaining enhanced convection along the ITCZ.

TUTT...
The TUTT enters the area near 24N180, extending west-southwest into a
TUTT cell centered near 21N166E, or just northwest of Wake Island,
then continues southwest to end near 16N151E. Patchy showers and
isolated thunderstorms are found with the TUTT cell northwest of Wake
Island. The TUTT looks to remain quasi-stationary as the TUTT cell
slowly drifts west, and may reach the Marianas by the middle of the
week.

...ITCZ...
The ITCZ remains active, extending east-northeast from just southeast
of Weno, Chuuk to end near 9N180. Scattered showers and isolated
thunderstorms are seen along the ITCZ, with the areas of numerous to
widespread showers found where the ITCZ is interacting with trade-
wind troughs. Incoming satellite scatterometer data, along with
earlier reports from weather station observations near Majuro,
indicated convective gusts around 35 knots (41 mph) are occurring in
some of the heaviest showers and thunderstorms. Seas are likely very
choppy near these showers and thunderstorms, creating hazardous
marine conditions. The ITCZ looks to remain active over the coming
days as it meanders around eastern Micronesia, likely pushing across
Chuuk State.

$$

Schank