637
AXPQ20 PGUM 260123
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1123 AM ChST Sat Apr 26 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...

NEAR EQUATORIAL TROUGH...
A Near Equatorial Trough (NET) enters the region near 5N130E,
extending east-southeast across southern portions of the Republic of
Palau and Yap State, to end near EQ145E in southeast Yap State.
Moderate to occasionally deep convection is associated with this
feature, producing numerous showers and some thunderstorms within 150
miles of the axis of the trough, as well as along the leading edge of
the monsoon-like surges buckling against the general trade-wind flow.
This region is becoming more favorable for cyclogenesis; a meandering
tropical disturbance in the Philippine Sea is expected to continue to
drift further toward the Philippines, inducing a consistent monsoon-
like surge and assisting in doldrum formation upstream. The weak
flow near the Equator is also indicated by the stable northwesterlies
making their way across the northern shores of Papua New Guinea,
which indicates a seasonal shift to a likely tropical disturbance
developing between 140E and 150E between 8N and the Equator in the
next 7 to 10 days. High uncertainty remains regarding potential
development of a significant tropical cyclone, so various agencies
will continue to monitor this area for any changes over at least the
next several days.

TRADE-WIND CONVERGENCE...
A trade-wind convergence zone extends across much of central
Micronesia, spanning from 140E to 160E between 9N and the Equator.
This is the result of trade winds clashing with the monsoon-like
flow induced by the aforementioned NET in western Micronesia,
producing numerous to widespread showers across much of Yap State,
Chuuk State and Pohnpei State. This region is expected to enhance
potential for cyclogenesis in eastern Yap State, providing the
necessary vorticity potentials and moisture flux to the NET
downstream, shifting northward as the convergence zone moves up along
the northern NET axis over much of the week.

A broad surface trade-wind trough extends from 9N150E west of
Chuuk, south-southwestward across much of eastern Yap State to end
at the Equator near EQ147E. Moderate to occasionally deep
convection is associated with this feature, producing scattered to
numerous showers and a few thunderstorms in a large sector from
143E to 152E, between 9N and the Equator. This feature is expected
to develop into a much more substantial convergence zone that will
span much of central and eastern Micronesia as early as Sunday,
becoming more active upstream for much of next week.

Other (albeit less active) surface troughs are observed elsewhere.
One is located well south-southwest of Wake Island, producing
scattered showers and some thunderstorms while interacting with a
slanted upper-level trough. Other troughs are producing scattered
showers well east of the Marshalls near the Date Line. These
features are expected to remain transient of nature for the next
several days, as they continue moving along with the trades.

UPPER-LEVEL TROUGH...
A laterally-positioned upper-level trough enters the region near
25N160E, extending west across Minamitorishima to end over the Far
Northern Marianas. Little to no convection is associated with this
feature, producing some shearing with passing minor surface troughs
below. This feature is expected to meander in the general vicinity
while the trough axis sharpens over the next several days, followed
by an embedded low developing northeast of Wake Island by midweek.

$$

Montvila