958
AXPQ20 PGUM 220106
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1106 AM ChST Wed Jan 22 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...

COLD FRONT...SHEAR LINE...
An eastward-moving cold front well north of the Marianas curves
southwestward through 25N151E to west of the Marianas near 18N140E,
then continues to beyond 14N130E as a shear line. Clouds and patchy
showers are seen along and up to 120 miles northwest of this
boundary. A few thunderstorms are found along the front, north of
24N. The front will continue eastward, largely staying north of 20N
while the shear line lifts northward, eventually aligning along 20N
by late week as a new high pressure system pushes into the north
Pacific off of Asia.

TRADE-WIND TROUGHS...
A westward-moving trade-wind trough is seen passing to the south of
Guam. The trough axis is roughly aligned along 145E between 4N and
12N with scattered showers found in the broad region between Yap
Island, Chuuk Lagoon and south of Guam. This trough will continue
westward, eventually bringing increasing showers to Palau and Yap
Thursday and into Friday.

TRADE-WIND SURGE...
The trade-wind surge across and north of eastern Micronesia is slowly
subsiding as a broad high pressure system well northeast of Wake
Island continues eastward into the north-central Pacific Ocean.
Late-morning ASCAT scatterometry data shows a broad region of 15-20
mph winds across central and eastern Micronesia from 5N northward to
the ridge axis near 20N. However, across the Marshall Islands and up
to 15N, scatterometry shows areas of 20-30 mph winds. Latest
altimetry data also shows combined seas of 7-9 ft south of 10N and
about 8-11 ft between 10N and 20N. Westward- moving showers are
present along the southern extent of the surge, roughly between 9N
and 12N, and merging into the ITCZ farther to the south. The surge
will only slightly weaken the next couple of days as the region
remains under the clear dominance of an easterly trade- wind flow.

OTHER SYSTEMS...

...ITCZ...
The ITCZ remains perched across eastern Micronesia between 4N and 7N
from Chuuk State eastward across the date line. A surface trough near
Chuuk is the focus for a large area of showers and a few
thunderstorms that are generally passing just south of Chuuk, today.
This trough will continue westward, bringing increasing showers and
thunderstorms to the outer islands of western Chuuk State and eastern
Yap State Thursday and Friday. Farther east, ITCZ moisture will
remain along a narrow band with occasional flare ups of heavier
showers, thunderstorms, and gusty winds. This convection will more
often affect Pohnpei and Kosrae, while undulating northward over the
central Marshalls from time-to-time.

$$

Aydlett