253
AXPQ20 PGUM 120100
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1100 AM ChST Sun Oct 12 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...
A trade-wind trough is located west of the Marianas between 10N
and 20N near 136E. However, convection is isolated in coverage and
small in size. A similar convective behavior will likely continue
the next few days despite PWATs above 2.5 inches as surface
convergence looks to remain meager.

Another weak trough stretches from Guam to the northern-most
portions of the CNMI. This feature is producing scattered showers
as evident by the Doppler radar imagery from Guam, but these
showers are small in size and relatively fast-movers. This
feature will continue westward the next few days with some
potential increase in convective coverage.

A broad circulation appears to be trying to form near Chuuk, with
a trough extending north from Chuuk to 16N154E. This feature is
mainly seen in the 925mb analysis and MIMIC imagery with PWATS
increasing to near 2.2 inches, which is below seasonal values
considering it`s wet season. Visible imagery also shows meager
convective development with imagery more reminiscent of a dry
season appearance.

TUTT...
The TUTT enters Guam`s AOR at 20N170E and extends to a cell
southwest of Wake Island at 16N163E, with the TUTT axis extending
southwest to 10N160 before turning west-southwest and ending south of
Guam at 9N145E. Numerous showers with scattered thunderstorms are
occurring near the cell, mainly along its western flank, with
scattered showers evident near the TUTT axis. Satellite imagery shows
abundant convection south of the axis near the ITCZ, as convection
there gets a boost of ascent via good divergence south of the TUTT
axis.

The cell southwest of Wake Island will continue its westward
journey for another 48 hours before turning northwest, reaching
20N150E by Tuesday as another cell crosses the dateline to near
15N177E. This effectively allows the TUTT to reorientate itself
with pressure and wind fields suggesting a strengthening will
occur.

...ITCZ...
The ITCZ stretches from southwest of Chuuk near 150E to the
Date Line and beyond, centered between 4N and 8N. Visible imagery
also shows a circulation trying to form southeast of Chuuk near
5N150E. The GEFS and ECENS show this circulation slowly organizing
as it heads northwest across the Marianas by the middle of next week,
with the GFS GDI also showing this. The GDI also shows that the ITCZ
itself from near Pohnpei will weaken some with convective coverage
as the divergence lifts north of the ITCZ, thus some decrease in
convection is probable. This then continues towards next weekend.

$$

Doll