393
AXPQ20 PGUM 160056
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1056 AM ChST Mon Jun 16 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 is a series of weak trade-wind troughs moving through
Micronesia that are interacting with the developing ITCZ. The first
of these troughs is seen well south of Guam, extending northeast
from near 4N143E to 10N149E. This trough is interacting with the
western end of the ITCZ to generate scattered to numerous showers and
isolated thunderstorms along the ITCZ west of the trough to 140E.
The next trough is found southeast of Weno, Chuuk, just west of
Kapingamarangi and Nukuoro. It extends north-northeast from near
1N154E to end near 8N157E. Scattered showers are found west of the
northern portion of the trough. The southern portion is also
interacting with the ITCZ to generate widespread showers and isolated
thunderstorms west of the trough from near Kapingamarangi and
Nukuoro to near 150E. The next trough is seen near Kosrae, extending
north-northeast from near 3N163E to end near 8N165E. A patch of
enhanced convection is seen along the ITCZ west of the trough south
of Mokil and Pingelap. The next trough is a little farther east,
south of Kosrae, extending northeast from near EQ165E to Majuro, near
7N171E. Numerous showers and isolated thunderstorms are found with
this trough/ITCZ interaction from south of Kosrae to a little south
of Majuro. The last trade-wind trough is seen east of the Marshall
Islands, extending north-northeast from near 2N177E to near 7N180.
Scattered to numerous showers and isolated thunderstorms are
associated along and east of this trough where it is enhancing
convergence along the ITCZ. All of these troughs will continue to
push west over the coming days, maintaining active convection along
the ITCZ.

TUTT...
The TUTT enters the region near 25N178E, extending south-southwest
to near 21N173E, then turns west-southwest, passing just north of
Wake Island to a TUTT cell centered just southwest of Guam near
12N143E. It then turns northwest to beyond 130E near 17N. Only spotty
clouds and showers are found along the TUTT east of the TUTT cell
across most of the area. However, stronger upper-level divergence is
enhancing convection across Minami Torishima and along the far
northeast corner of the region. With the TUTT cell and the trough
west of the cell, strong divergence to the south is interacting with
a weak low-level circulation and trough to enhance convection near
Yap Proper, Ngulu, Ulithi and Sorol. The TUTT is expected to remain
quasi-stationary over the coming days while the TUTT cell drifts
west. Little change in intensity is expected.

OTHER SYSTEMS...
A weak circulation is centered south of Yap Proper near 5N140E, with
a trough extending northwest to end north of Palau near 10N134E.
This trough and circulation is interacting with divergence
associated with the TUTT to generate enhanced convection over Yap
Proper and other islands over northwestern Yap State. This system
looks to meander around the area with a possibly eastward drift due
to a weak high that developed to the southwest of Palau.

A weak high pressure ridge developed to the southwest of Palau. This
ridge is helping to suppress convection across Palau. The high is
expected to drift west and weaken over the next couple of days.

...ITCZ...
A long, and sometimes broad, ITCZ extends east across the Date Line
near 5N to south of Majuro, Kosrae, Pohnpei and Weno, Chuuk to near
4N150E, then turns toward the west-northwest to end northeast of a
weak circulation centered near 5N140E. Scattered to widespread
showers and isolated thunderstorms are found along the entire extent
of the ITCZ, with greatest coverage found along points where the
ITCZ is interacting with weak trade-wind troughs passing through. The
ITCZ looks to meander north and south over the next few days with
little change in intensity. Associated convection will continue to be
enhanced along interaction points with the weak trade-wind troughs
that will move through the region.

$$

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