487
AXPQ20 PGUM 310052
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1052 AM ChST Fri Jul 31 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 CYCLONES...
STY Dolphin (12W) continues to churn in the WestPac, with current
satellite-derived position estimates showing the LLCC is 18N162E,
or west-southwest of Wake Island, and moving away from there. The
7 AM ChST advisory showed increased sustained winds of 155 mph,
with gusts to 190 mph likely occurring. Maximum significant wave
height is 44 feet. Dolphin is forecast to make a brief turn to
the northwest with a slight increase in forward speed through
Saturday, before turning more to the west sometime early next
week, potentially slowing its forward speed, and eventually
weakening somewhat as it heads towards Iwo To.

For more information please refer to bulletins from the Joint
Typhoon Warning Center under WMO header WTPN31 PGTW and from
the National Weather Service under WMO header WTPQ31 PGUM.

TROPICAL AND MONSOON DISTURBANCES...
Northwest of Koror and Yap we have Invest 94W, which is located
near 14N133E. 94W continues to be rated as "Sub-Low" from JTWC,
indicating the formation of a tropical cyclone is unlikely over
the next 24 hours. This system is expected to continue moving
northwest over the next few days, with it exiting Guam`s AOR in
about 72 hours. It`s not entirely out of the question that an
upgrade in rating from JTWC is possible through then, but the
tropical disturbance will remain weak while traversing the
remainder of the Philippine Sea within Guam`s AOR.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The monsoon trough enters Guam`s AOR at 13N140, and extends east-
northeast to 94W. It then continues east-northeast, crossing near
Saipan in the CNMI, before linking up with STY Dolphin. From
there, the trough dives southeast, passing through a col at
8N177E, before exiting Guam`s AOR near 8N180. Scatterometer
analysis shows two main "cores" of WWBs. The first is between 7N
and 10N from 130E to 143E, including northern Palau and Yap. Here,
sustained winds of 15 to 20 knots are common. The second area is
associated with STY Dolphin, and is centered between 4N and 11N
from 150E to 170E, including Chuuk, Pohnpei, and Kosrae. Here, a
broad area of 15 to 20 knot sustained winds are common, with a
burst of 20 to 25 knots between ~155E and 165E, impacting Pohnpei
and Kosrae. Then, as you get near 170E, the monsoon flow becomes
much more southerly, increasing accordingly as you get closer to
the LLCC of Dolphin.

In terms of convective activity, it`s greatest around the
peripheries of 94W, Dolphin, and in the second WWB, between ~6N
and 11N, from 145E to 170E. This includes Chuuk, much of eastern
Micronesia, and a good portion of the RMI respectively. Over the
next few days, the monsoon trough is expected to gradually lift
north and strengthen, with increasing areal and intensity of
convection probable. This could make the forecast "modestly-
interesting" for Guam and the CNMI. Stay tuned!

TRADE-WIND TROUGHS...
A trade-wind trough extends north from 94W to 20N, before turning
northeast and ending near a col north-northwest of Iwo To.
Scattered showers and a few thunderstorms are found along and near
this trough between 14N and 18N, with convection more shallow and
sparse along and near the remainder of the trough. This will
continue to be the convective pattern over the next few days,
until 94W and the attendant trough exits Guam`s AOR.

$$

Doll