731
AXPQ20 PGUM 032319
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
919 AM ChST Mon Aug 4 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...

TROPICAL AND MONSOON DISTURBANCES...
The Remnants of Iona are located near 22N171E, or northeast of Wake
Island. Convection associated with Iona has begun to wane over the
last 12 hours as the storm continues to dissipate. The remnants of
Iona will continue to drift northwest with no strengthening expected
over the next couple of days.

...OTHER WEATHER SYSTEMS...

NEAR EQUATORIAL TROUGH...
A Near Equatorial Trough (NET) extends from EQ145E to 4N150E. This
trough is interacting with a trade-wind trough to produce scattered
to numerous showers and isolated thunderstorms. The NET is forecasted
to amplify and move westward over the coming days.

TRADE-WIND TROUGHS...
There are a couple of trade-wind troughs seen across the region. The
first is located just west of Chuuk and east of the Marianas. The
trough extends from 2N147E to 14N154E. Scattered showers with pockets
of numerous showers are seen along this trough as well as isolated
thunderstorms. This trough will shift westward and amplify over the
next few days. A weak circulation may form just north of Yap within
the trough later this week.

The second trough is located just west of Majuro, extending from
4N170E to 9N170E. There are isolated showers and thunderstorms seen
along the trough axis. This trough looks to briefly wash out later
today before amplifying over Kosrae and Pohnpei late Tuesday night.

TUTT...
There are a couple of disconnected TUTT features across the region.
The first is a TUTT cell just west of the Marianas, located near
15N143E. The TUTT cell is interacting with a weak circulation north
of Yap to produce a thunderstorm complex southwest of Guam. The TUTT
is also producing scattered showers and isolated thunderstorms to the
north and east of the Marianas. This feature is expected to move
west quickly, exiting the region by Wednesday night as it weakens.

A second TUTT enters the region at 25N180 and extends southwest
towards a TUTT cell located near 12N171E, and then continues westward
to 15N155E. Little activity is seen along this TUTT with the
exception of some isolated thunderstorms northwest of Majuro where
the TUTT is interacting with a trade-wind trough. The TUTT is
forecasted to move westward and intensify later this week.

OTHER SYSTEMS...
A weak circulation is seen north of Yap or near 12N138E. The
circulation is producing numerous to widespread showers and scattered
thunderstorms on the west side and a thunderstorm complex on the
eastern edge. The circulation is interacting with a TUTT to the
northeast, which is likely enhancing convection. The circulation is
expected to move westward and leave our region Wednesday or Wednesday
night. No development is expected while the circulation is within
our Area of Responsibility (AoR), but some develop may be possible
further west in the Philippines Sea.

A surface ridge currently extends from south-southeast of Guam into
Yap State and well southeast of Palau. Or, from about 12N146E to
3N140E. This ridge is producing calm weather across parts of western
Micronesia with surface divergence seen across Yap and Palau. The
ridge is forecasted to weaken as it shifts westward due to an
amplifying trade-wind trough moving in from the west.

$$

Williams