680
AXPQ20 PGUM 040133
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1133 AM ChST Tue Nov 4 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...
A monsoon trough enters Guam`s AOR near 9N130E and passes through
Koror to Invest 90W in eastern Yap State near Satawal, or near
10N147E. This disturbance is the subject of a TCFA (Tropical
Cyclone Formation Alert), meaning the formation of a tropical
cyclone is likely within the next 24 hours. This system may become
a tropical depression later today and a tropical storm by
Wednesday as it heads northwest. South of the monsoon trough,
widespread cloud cover with scattered showers and isolated
thunderstorms is occurring, with the heaviest axis of
precipitation from Helen`s Reef in southern Palau to east-central
Yap State. Some of this rainfall is locally intense across
portions of Yap State as evident by cloud top temperatures
exceeding -80 deg. C. Wind gusts to 40 mph are probably occurring
as well.

The current track would allow the system to pass southwest of
Guam, but, this may change as the system is still in the early
stages of formation. It will bring periods of heavy rain and gusts
winds to Guam and the CNMI starting Wednesday evening and
continuing through at least Thursday, possibly into Friday.

For more information on Invest 90W please see bulletins for the
Western Pacific Ocean please see the TCFA header under WMO WTPB21
issued by the Joint Typhoon Warning Center.

...OTHER WEATHER SYSTEMS...

SURFACE TROUGHS... A trade-wind trough extends northeast from
Invest 90W near 8N147E to 15N152E ending near 22N154E. Scattered
showers and isolated thunderstorms are mainly confined to the
northern portion of the trough from 15N to 22N. This is due to the
interaction of an upper low east of the Marianas near 15N153E and
a upper high near Wake Island.

A large area of convection is located west of Wake Island with
widespread showers, some locally heavy, and isolated to scattered
thunderstorms occurring. Wind gusts to 35 mph have occurred at
Wake Island, with seas of 10 to 15 feet in the area. This is due
to great directional divergence aloft, which should weaken in the
coming days as the pattern reorientates itself.

The trough will continue moving west in a similar convective
behavior, becoming displaced from the upper high and low. However,
it (the trough) will then get absorbed into what`s expected to be
a tropical depression or tropical storm west of the Marianas late
Thursday or Friday. It should then transition into a monsoon
trough extension from the developing system.

A third trough in the trades is located between Majuro and Kosrae,
stretching from near 6N169E to near Bikini Atoll, ending at
11N165E. Moisture is somewhat modest with MIMIC imagery showing
PWATs of 2.1-2.5 inches, but surface convergence is compensating
with the net result being widely-scattered showers and isolated
thunderstorms developing between Kwajalein and Jaluit. Modest
divergence aloft is helping to allow for brief bursts of locally
intense convection where cloud top temperatures push -75 deg. This
feature will continue west the next several days with scattered
convection continuing to develop.

TUTT...
The TUTT enters Guam`s AOR near 15N180 and extends west to an
upper low east of the Marianas near 15N153E, with the TUTT axis
ending near Saipan at 16N146E. Scattered convection from the
Marianas eastward along the axis is occurring, increasing to
numerous showers and isolated thunderstorms near the Date Line and
points eastward.

The western half of the TUTT will get pinched-off and dissolve
during the next few days as high pressure aloft forms near Guam,
atop the developing tropical system by Thursday night. The
orientation of the TUTT will then be dependent on how the tropical
system evolves.

$$

Doll