745
AXPQ20 PGUM 250101
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1101 AM ChST Mon Nov 25 2024

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...
Several trade-wind troughs are seen moving across Guam`s Area of
Responsibility (AOR). A weak, shallow trade-wind trough is seen
just east of the Marianas, extending south-southwest from around
17N147E to 12N145E. Scattered showers are seen northeast of Saipan
along the northern edge of the trough axis, but are fairly spotty
elsewhere in the area. This trough will shift west of the
Marianas through the overnight hours, increasing the potential for
showers across the area in the meantime, mainly for Tinian and
Saipan.

To the south, a few trade-wind troughs are seen within a broad
convergence boundary over western Micronesia. The first of these
is seen southeast of Koror near 7N136E, extending southeast to
around 4N140E. The second trough is seen over Yap State from east
of Ulithi near 10N141E, extending southeast to around 5N145E
passing just over Eauripik Atoll. Numerous showers and isolated to
scattered thunderstorms are seen across the region within the
broader convergence zone, mainly focused along the axes of these
troughs. Looking further east, there is a third trade-wind trough
located just west of Chuuk, extending south-southwest from around
9N151E to near 2N150E. Scattered to numerous showers are spread
across the area, loosely focused around the trough axis southwest
of Chuuk but are largely separate from the convergence boundary
mentioned above. These features will gradually shift west-northwest
over the next few days and maintain showers across western
Micronesia through midweek, consolidating into a broader trough
over the region.

A series of weak north-south oriented trade-wind troughs are seen
across eastern Micronesia, with one trough located just east of
Pohnpei, another just west of Kwajalein Atoll, and a third trough
just east of the Ratak Chain northeast of Majuro Atoll. Showers
are scattered across the region with little organization, focused
mainly across portions of the northern Marshall Islands. These
troughs will shift west and lose definition over the next day or
so, looking to gradually merge into a stronger trough somewhere
just west of Pohnpei come Tuesday night.

TRADE-WIND SURGE...
Scatterometry data from last night and this morning shows a broad
region of moderate to fresh trade winds extending across much of
the AOR from 130E to 180, mainly between 5N and 20N. Surface
observations across the Marianas and western Micronesia show
moderate to fresh sustained winds with a few gusts exceeding 20
knots. Trade winds look to strengthen slightly across the Marianas
over the next few days with sustained winds approaching 20 knots
at times. Strong gusts could become frequent, especially near
showers. These elevated winds will contribute to an unsettled,
choppy sea state in addition to a higher trade swell, which could
make marine conditions hazardous to small craft at times this
week. Model guidance shows that this trade wind surge will
gradually weaken during the latter half of this week from west to
east, as strong subtropical ridging north of the Marianas shifts
eastward enabling the pressure gradient to relax.

ITCZ...
The Intertropical Convergence Zone (ITCZ) has weakened and become
indistinct over eastern Micronesia. Showers are isolated to
scattered across the region over the Marshall Islands, Kosrae
State, and Pohnpei State. To the west, a few discontinuous,
decaying fragments of the ITCZ are seen west of Chuuk and south of
Yap Proper within a broad region of trade-wind convergence,
extending west from near 6N145E, passing south of Koror and
exiting the AOR near 5N130E. Numerous showers and isolated to
scattered thunderstorms are seen along this disorganized
convergence boundary, mainly across Yap State to the south of Yap
Proper, and west of Koror extending beyond the edge of the AOR
just east of Mindanao. An upper-level trough is located over the
Marianas just north of this feature, and may be helping to enhance
deep convection and associated strong gusts across the area.
Himawari visible satellite imagery shows some evidence of cross-
equatorial east-southeast flow into the eastern edge of the
convergence zone, mainly over southeast Yap State near Eauripik
Atoll, but it is very weak. This remnant ITCZ-like convergence
boundary will continue to bring showers across western Micronesia
over the next few days, gradually lifting north into the latter
half of the week and increasing showers near the Marianas Thursday
onward.

$$

DeCou