422
AXPQ20 PGUM 180022
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1022 AM ChST Wed Jun 18 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...

TRADE-WIND TROUGHS... There are a few trade-wind troughs seen
across the region. The first is located to the west of the
Marianas, extending north-northeast from near 11N140E to 16N142E.
This trough is interacting with divergence associated with a TUTT
cell to produce scattered showers and isolated thunderstorms west
of the Marianas, north of Yap. This trough will continue to move
west over the next few days, remaining under the influence of the
TUTT through at least the next 24 hours.

The next trade-wind trough is found just southwest of Weno,
Chuuk, extending southeast to end east of Nukuoro near 4N157E.
Scattered showers and isolated thunderstorms are seen over Satawal
to southeast of Weno to east of Nukuoro. The next trough is just
a little farther east, extending southeast from just east of
Pohnpei near 7N159E to end near 1N163E. Scattered showers and a
couple of thunderstorms are seen with this trough. Both of these
troughs and associated convection will continue to move west over
the next couple of days.

TUTT... The TUTT enters the area near 25N175E, stretching west-
southwest to a TUTT cell centered near 21N150E. Scattered showers
and isolated thunderstorms are seen within the area of the
strongest divergence north of the trough, north of Wake Island.
Patchy clouds and showers are found along the remainder of the
trough until east of 155E. From 155E to the TUTT cell, scattered
showers and isolated thunderstorms are found with the divergence
associated with the trough and cell between 17N and 22N, east of
the northern CNMI. The TUTT then continues west-southwest to
another TUTT cell centered near 18N138E, then continues southwest
to beyond 130E near 10N. Patchy clouds and showers are present
along the trough between the two cells. Scattered showers and
isolated thunderstorms are seen to the west of the Marianas where
a weak trade-wind trough is interacting with the divergence seen
to the southeast of the cell. Scattered showers and isolated
thunderstorms are also seen just north of the trough that extends
southwest from the second cell in the area of the strongest
divergence. The TUTT is expected to remain quasi-stationary as the
cells slowly drift west over the coming days.

OTHER SYSTEMS... A mid-latitude high pressure system is centered
near 27N136E. An area of convergence is seen to the south of this
high pressure system, producing scattered showers and
thunderstorms between 25N and 20N, west-southwest of Iwo To. This
high pressure system will move east over the coming days.

To the east of the high, a weak circulation is seen centered near
25N150E, with a trough extending south-southwest to end north of
Maug near 21N146E. The high pressure is enhancing convergence
along the trough, while upper-level divergence between a TUTT cell
and the upper-level ridge is interacting with the trough. This is
producing scattered to numerous showers with isolated
thunderstorms along and west of the trough. The trough and
associated convection will slowly move east as the high
progresses.

...ITCZ...
A fragment of the ITCZ is seen over far western Micronesia, south
of Yap and Palau, extending west-northwest from near 2N140E to
near 5N130E. This fragment of the ITCZ drifted into the area from
central Micronesia and continues to weaken. It is producing
scattered showers and isolated thunderstorms along and to its
south. The fragment is expected to continue to weaken and drift
west-southwest over the coming days.

Farther east, a weak ITCZ extends west across the Date Line near
7N, extending west, passing just south of Majuro, ending just
north of Kosrae near 7N161E. Mostly scattered showers are found
from a little east of Majuro to the western end of the ITCZ, with
a few thunderstorms seen near Kosrae. Spotty clouds and showers
are seen farther east of Majuro to the Date Line.

$$

Kleeschulte