979
AXPQ20 PGUM 172352
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
952 AM ChST Sat Oct 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...
The trough that was near Chuuk yesterday now stretches from near
Gaferut in east central Yap State through the Marianas to west of
Saipan near 15N144E. Scattered showers and a few thunderstorms
continue to accompany this feature, and this looks to be the case
the next several days as it continues heading west.

A new trough has developed in the streamline analysis from just
west of Kosrae near 5N162E, stretching north-northwestward and ending
near 17N158E. No convection is tied to this feature currently,
but the models show this will change with scattered convection
developing along it by the middle of next week (maybe earlier) as
it continues its westward journey.

A third and fairly robust trough stretches from east of Ebon in
the RMI near 5N168E northeastward to Majuro before ending near
12N172E. Pockets of numerous showers with isolated thunderstorms
are occurring. Additionally, locally heavy rainfall is also
probable given cloud top temperatures of -75C or colder. This
feature has been well-advertised/handled by the models, as they
forecast a similar convective behavior over the next several days
as it also heads west.

TUTT...
Today the TUTT remains fairly broad as it stretched from a mid-
latitude trough to its north, with this trough transitioning to a
TUTT where it connects with a slowly-developing cell northwest of
Wake Island near 21N160E, extending south-southwest to another
slowly-developing cell between Guam and Chuuk near 10N149E. The
TUTT axis then continues south-southwest to another developing
cell near 1N146E. Most of the convection is found near the
periphery of the northern two cells, and to the east of the TUTT
axis as modest divergence helps ventilate cloud tops, aiding in
updraft intensity.

Overall the TUTT and its axis looks to remain quasi-stationary,
taking several days to drift west, reaching Guam and the CNMI
while also extending south through east central Yap State sometime
during the first half of next week. No appreciable strengthening
is forecast to occur as it does so.

$$

Doll