565
AXPQ20 PGUM 170101
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1101 AM ChST Tue Jun 17 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...

TRADE-WIND TROUGHS...
There are several trade-wind troughs moving through Micronesia, with
a series of these troughs interacting with the ITCZ. The first trough
is found just east of Palau, extending north from near 2N134E to
near 11N136E. Scattered showers are seen west of the trough over
Palau, with scattered to numerous showers and isolated thunderstorms
seen over the extreme southwest corner of the region. This trough
will move west and out of the region over the next couple of days.

The next trough, the first in a series interacting with the ITCZ, is
seen over the western end of the ITCZ, extending north-northeast
from near 1N142E to near 9N144E. Scattered showers are found west of
the trough, with scattered showers and isolated thunderstorms where
the trough is interacting with the ITCZ. Another trough is seen just
a little farther east, extending northeast from near 1N145E to near
4N150E. Scattered showers and isolated thunderstorms are seen west
of the trough with the ITCZ. The third trough in the series is found
south of Pohnpei, extending northeast from near 1N153E to near
5N156E. Scattered showers are associated with this trough along the
ITCZ. This series of troughs will continue to move west along the
ITCZ over the next couple of days.

Another weak trade-wind trough is found to the west of Kwajalein,
extending north from near 5N166E to near 8N167E. Patchy clouds and
showers are found with this trough. The trough will move west over
the next couple of days, bringing increased convection to Kosrae and
Pohnpei.

The last trade-wind trough is found just east of the Marianas,
extending north-northeast from near 10N144E to near 13N146E. This
trough is interacting with divergence associated with the TUTT and a
TUTT cell, centered near 14N140E, to produce scattered to numerous
showers and isolated thunderstorms southwest of Guam, with scattered
showers and couple thunderstorms over Guam and Guam waters.

TUTT...
The TUTT stretches southwest, entering the area near 25N180 to near
16N159E. The TUTT then turns northwest across the northern CNMI near
19N148E, where it turns southwest, passing through a TUTT cell
centered near 14N140E to end near 7N130E. Numerous showers and
isolated thunderstorms are found north of the TUTT, northeast of
Wake Island, in the area of the strongest upper-level divergence
with a weak trough moving through. Another area of divergence north
of the TUTT is generating scattered showers and isolated
thunderstorms north of 20N from 150E to 160E. Divergence to the east
of the TUTT cell is interacting with a trade-wind trough to generate
scattered to numerous showers southwest of Guam with scattered
showers and couple thunderstorms over Guam and Guam waters. The TUTT
cell will continue to slowly drift west, while the TUTT remains
quasi-stationary over the coming days.

OTHER SYSTEMS...
A weak surface trough is located northeast of Wake Island, extending
north from near 21N169E to beyond 25N near 169E. This trough is
interacting with divergence associated with the TUTT to generate
numerous showers and scattered thunderstorms northeast of Wake
Island. The trough will continue to move northwest over the next
couple of days, moving away from the divergence.

...ITCZ...
The ITCZ has weakened a bit over portions of eastern Micronesia. The
ITCZ enters the area near 6N180, then becomes very diffuse from
6N175E to south of Kosrae near 4N162E. Little to no convergence nor
convection is seen between 175E and 162E. The ITCZ then becomes more
organized from 3N162E to end near 8N138E, south of Yap Proper.
Several trade-wind troughs are interacting with the ITCZ to produce
patches of scattered to numerous showers and isolated thunderstorms
south of Yap Proper, well south of Guam south of Weno, Chuuk and
south of Pohnpei. The ITCZ looks to drift west over the coming days
as it gradually dissipates.

$$

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