677
AXPQ20 PGUM 010143
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1143 AM ChST Tue Jul 1 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...
There is now one disturbance across the region, JTWC Invest 90W. 90W
is not currently showing a defined circulation center, but is
roughly located well north-northeast of Saipan near 21.4N 148.2E,
moving northward. Numerous showers and isolated thunderstorms are
found to the east of the invest. 90W is now rated low, meaning it is
expected to develop, but not expected to become a significant
tropical cyclone within the next 24 hours. Although a closed
circulation is not seen now, 90W is becoming more organized, with a
TUTT cell near 21N145E providing divergent flow in the upper levels.
Models do favor 90W developing into a more organized circulation as
it continues north. For more information on Invest 90W, see bulletins
issued by JTWC under WMO header ABPW10 PGTW.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The monsoon trough extends east across 130E near 16N, through a weak
circulation centered near 16N139E, then turns east-northeast through
Invest 90W to end near 21N151E. Strong upper-level divergence
associated with the TUTT and a TUTT cell is helping to enhance
convection seen to the south of the monsoon trough. This convection
is also being aided by a weak monsoon surge moving through northern
Palau and Yap State, to the southwest through west of Guam. Numerous
to widespread convection is found north of Palau and Yap Proper,
west of Guam and Rota. The monsoon trough looks to continue to be
pulled north with Invest 90W over the next couple of days, with
decreasing convection as the monsoon surge weakens.

TRADE-WIND TROUGHS...
Three trade-wind troughs are evident over the region. The first is
seen just west of Weno, Chuuk, stretching north-northwest from near
1N153E to near 10N150E. Only spotty clouds and showers are seen with
this trough as upper-level convergence is helping stabilize the area.
The trough will continue to move west-southwest over the coming
days, with increasing convection as it moves away from the influence
of the upper-level convergence.

The second trough is seen east of Kosrae, extending north from
1N165E to 9N166E. Patchy showers and isolated thunderstorms are
found with the trough. This trough looks to move west over the next
couple of days, with increasing convection as it moves into an area
of better upper-level divergence over Kosrae.

The last trade-wind trough is found east of Wake Island, extending
north from near 13N169E to 21N169E. This trough is interacting with
divergence associated with a TUTT cell centered near 16N170E to
produce numerous showers and isolated thunderstorms just east of Wake
Island. The trough will continue to move west-southwest over the next
few days.

TUTT...
The TUTT remains fragmented. The first fragment is seen entering the
region near 24N180, extending west to near 24N176E, where it turns
south-southwest, passing through a TUTT cell, centered near 16N170E,
to end near 2N160E. Divergence northwest of the trough and cell is
interacting with a weak trade-wind trough to produce numerous
showers and isolated thunderstorms east of Wake Island. This fragment
of the TUTT and cell look to remain quasi-stationary over the coming
days.

Another TUTT fragment and cell are located near the monsoon trough.
The TUTT enters the area near 25N145E, extending south to a cell
centered near 21N145E, then continues south-southwest to end near
13N130E. Divergence associated with this TUTT and cell is seen over
a large area and is enhancing convection south of the monsoon trough
and near Invest 90W. This fragment of the TUTT and cell look to
remain quasi-stationary and slowly weaken over the next few days.

OTHER SYSTEMS...
A surface trough extends southeast across 130E near 13N to end over
Palau near 7N133E. Another weak trough is seen west of 130E. These
troughs are helping to increase convection from Palau south to the
equator. These troughs look to move toward the northeast over the
next few days, maintaining intensity and convection over Palau.

...ITCZ...
The ITCZ extends west across the Date Line near 4N to end near Kosrae
at 5N164E. This feature has weakened a bit over the last 24 hours.
Scattered to numerous showers are found between Majuro and Kosrae in
the area of the strongest convergence. Isolated to scattered showers
are near Majuro eastward. A trade-wind trough is helping to keep the
ITCZ alive near Kosrae, with increasing convection expected as the
trough moves west into an area of upper-level divergence.

$$

Kleeschulte