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AXPQ20 PGUM 250046
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1046 AM ChST Sat Jul 25 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...

TROPICAL AND MONSOON DISTURBANCES...
Invest 93W retains a "Sub-Low" rating from JTWC, and it`s located
well to the northeast of Pohnpei, near 12N162E. COnvection
(elevated) continues to develop along the southern flank of the
disturbance, and this may continue for another day or two. After
that, it remains unclear if this system will develop further,
and/or affect the Marianas, as some model guidance suggests, or if
it`ll wash out, which is on the other side of the model guidance
fence. Other than that, if it maintains itself, it`ll continue on
a due west heading for another 48 to 72 hours, before potentially
turning northwest. It`s in a moderate shear environment, with
200mb winds currently around 15 knots, which isn`t helping
matters, nor is somewhat drier air ahead of the system near 155E.
We`ll see what happens over the next few days.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The monsoon trough has modified its orientation slightly, due to
93W having become more convectively active, and Typhoon Noul (11W)
having dragging it further north. So for today, the trough enters
Guam`s AOR at 17N130E and extends east to a col at 17N132E. It
then turns southeast, passing through a developing broad/weak
circulation south of the Marianas east of Gaferut in eastern Yap
State, near 9N148E. It then continues east, reaching another col
northwest of Pohnpei near 9N167E. Here, it turns northeast to link
up with Invest 93W at 12N162E, before diving southeast through a
col just east of Kwajalein. It then continues east-southeast,
exiting Guam`s AOR at 8N180. Convection continues to develop in
the west to southwest flow along and south of the trough,
generally within 5 or 6 degrees of latitude in relation to its
orientation (roughly between 4N and 10N once you get east of
140E).

Overall, the monsoon trough looks to reorientate in an east-west
form near 10N over the next few days, before a disturbance
currently near 8N172W potentially drags the trough further north.

SURFACE TROUGHS...
The first surface trough extends northwest from EQ140E to the
southern edge of a col near 15N132E. Most of this trough is void
of convection, with the exception being between 10N and 14N near
132E. Here, widespread showers and scattered thunderstorms are
occurring due to good surface convergence, aided by moderate to
strong divergence aloft. This trough will stay convectively active
until it crosses 130E, out of Guam`s AOR, in the next 24 to 30
hours.

The next surface trough extends north from 93W to west-northwest
of Wake Island near 21N162E, where it ends. Scattered showers are
developing along this feature, with several thunderstorms also
occurring between 18N and 21N, where moderate surface convergence
is aided by moderate divergence (speed increase of 20 knots or so
at 200 mb compared to locations south of there). This trough
should stay active for another day or two, after that, it`ll at
least partially depend on what happens to 93W, and how the pattern
starts to reorientate itself as the disturbance east of the Date
Line (currently) crosses it and begins to affect the downstream
synoptic pattern.

OTHER SYSTEMS...
The tail end of a front enters Guam`s AOR near Minamitorishima,
extending southwest to a col between Saipan and a weak/small area
just southeast of 20N140E. The remains of this front continue to
weaken, but similar to today, will continue to produce a broken
line of showers along it for another 24 to 36 hours. After that,
it should have dissipated.

$$

Doll