511
AXPQ20 PGUM 050105
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1105 AM ChST Wed Feb 5 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 Joint Typhoon Warning Center has open Invest 92W, centered near
5N134E, to monitor the broad cyclonic motion seen within the near-
equatorial trough (NET) that extends across western Micronesia near
Palau. The CIMSS MIMIC TPW satellite product shows two weak
circulations, one west of Palau near 8N131E and the second southeast
of Palau near 4N138E, embedded within the NET. The latest CIMSS
satellite tropical analysis, shows the 850-500mb vorticity layer is
still spread out across the NET, so the potential for 92W to develop
into a tropical cyclone within the next 24 hours is very low. The
broad area of vorticity is expected to slowly drift westward towards
the Philippines, with some consolidation into single broad
circulation. More detail on the NET and associated precipitation
pattern is discussed in more detail below.

...OTHER WEATHER SYSTEMS...

NEAR EQUATORIAL TROUGH...
A Near-Equatorial Trough (NET) enters the region near 9N130E,
extending southeast across the Republic of Palau (ROP), extending
through two embedded circulations near 8N131E and 4N138E, and then
ending near the equator around 147E, well south of Satawal in Chuuk
State. Satellite imagery shows extensive cloud cover and scattered
showers across most of Yap State and the ROP, with the heaviest
showers and isolated thunderstorms located near the equator, well
south of Palau. The NET is expected to strengthen slightly, before
weakening by the weekend as a trade-wind surge wipes out this feature
and shifts the bulk of the convergence toward the waters southeast
of Mindanao.

TRADE-WIND TROUGHS...
Most trade-wind troughs are hard to distinguish, as they blend in
the general trade-wind flow and remain transient in nature. One
of the more notable troughs is embedded within the ITCZ, to the east
of Kosrae extending from 2N165E to 6N167E, causing convection along
the ITCZ to lift northeastward towards Jaluit in the Marshall
Islands. These features will continue to increase and decrease in
strength as the pressure gradient varies across the region throughout
the week.

OTHER SYSTEMS...

REMNANT OF A SHEAR LINE AND COLD FRONT...
Remnants of a shear line extend west-southwestward from 25N155E near
Minamitorishima, across Maug in the Far Northern Marianas, and then
extends southwest to cross 13N130E northwest of Palau. There is very
little shower activity along the shear line, just dissipating
stratifying clouds within 150 miles of the shear line. Further north,
a new cold front is moving southeastward and into the region near
25N145E and extending to 16N130E. There is very little shower
activity along the cold front within the region, just a cumulus
field, with scatterometer showing 20 to 25 kt winds extending
northward from cold front up to Japan. The shear line is expected to
dissipate under a lackluster pressure gradient as it dips further
south and then fragments, getting carried away by the trades over the
coming days. The cold front will shift southward, slowly replacing
the old shear line as it transitions into a shear line this weekend.

...ITCZ...
An Intertropical Convergence Zone (ITCZ) enters the region near
6N180, extending west-southwestward across much of eastern
Micronesia south of Majuro and Kosrae and Pohnpei, and falling apart
south of Chuuk near 4N154E. A significantly convective sector of the
ITCZ remains along the strongest portion of the convergence zone
bringing widespread showers and some thunderstorms just south of
Kosrae and eastern Pohnpei State, that then extends towards Majuro
but starts to weaken near Jaluit. Scattered showers are associated
with this feature elsewhere. This feature is expected to strengthen
in convection, as the pressure gradient will increase between the
mid- latitudes and the tropics due to a shifting subtropical high in
the western Pacific.

$$

Schank