535
AXPQ20 PGUM 190012
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1012 AM ChST Sat Sep 19 2026

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...

MONSOON TROUGH...
Today the Monsoon Trough enters Guam`s AOR at 15N130E and extends
east through Saipan, before turning east-southeast as it passes
through a col north-northwest of Pohnpei near 13N156E. It then
continues east-southeast to a broad circulation near Kwajalein,
before exiting the AOR at 8N180. South of the trough, west to
southwest flow persists, except between the Pohnpei col and
Kwajalein circulation, where the flow is west-northwest. A
"ribbon" of moisture is found between 10N and 14N from 130E to
150E, before diving southeast through Pohnpei and Kosrae. It (the
moisture ribbon) then gets absorbed into the Kwajalein
circulation and extends northward along a surface trough to near
25N171E, while also extending east from Majuro to the Date Line.
In these areas, scattered showers and widely-scattered
thunderstorms persist.

Moisture also peels north between the Marianas and 153E as it`s
part of the inflow into Tropical Storm Dujuan north of the area.
Here too, scattered showers and thunderstorms are occurring. This
is expected to weaken over the next few days as Dujuan continues
to move away from the region.

As a side note, south of the "ribbon" of moisture, abundant dry
air crossing the equator and weak convergence has precluded
convective development south of Koror and Yap, with 100-850mb ALPW
(All-Layer Precipitable Water) values under 0.8 inches, with
MIMIC showing less than 1.5 inches of moisture, which is pretty
dry for this area.

The Monsoon Trough looks continue to gradually settle south the
next few days, before stalling out near 12N for the portion
northwest of Pohnpei, with the remainder of it further east
maintaining it`s current position/alignment. Scattered convection
will likely continue along and immediately south of it through
early next week.

SURFACE TROUGHS...
A surface trough extends north from near Kwajalein to east of Wake
Island at 19N170. Moisture pooling long it combined with
respectable directional convergence will continue to foster
scattered convective development along and east of it (behind
it), with this feature expected to slowly progress westward over
the next few days.

$$

Doll