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AXPQ20 PGUM 190129

TWDPQ 



Tropical Weather Discussion

National Weather Service Tiyan GU

1129 AM ChST Sat Jul 19 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...



MONSOON TROUGH...

The monsoon trough enters the region near 11N130E, extending

southeast to south of Yap Proper near Ngulu, where it then turns

south-southeast to end at the equator near 140E. Scattered to 

numerous showers and isolated thunderstorms are found with the band 

convergence found north and east of the trough from 130E across Yap 

Proper, then southward to beyond the equator. South and west of the 

trough, a monsoon surge is generating numerous showers and isolated 

thunderstorms over Palau. The monsoon trough is expected to drift 

northeast over the coming days, bringing increased moisture into the 

Marianas and maintaining a wet pattern across Palau and Yap.



TRADE-WIND TROUGHS...

Several trade-wind troughs are evident across the region. The first

is seen west of Weno, Chuuk, extending west-southwest from near

8N149E to end near 3N144E. Scattered to numerous showers and 

isolated thunderstorms are seen with the trough over Gaferut, 

Satawal and Eauripik. This trough will move northwest over the next 

few days and will likely interact with the monsoon trough over Yap 

Proper.



The next trough is seen just east of the Marianas, extending south

from near 14N147E to end near 10N146E. Convergence with the trough 

is interacting with upper divergence associated with the TUTT to

generate convection in the form of scattered to numerous showers and

isolated thunderstorms across and west of the Marianas. This trough 

will continue to move west over the coming days.



Another elongated trough is found west of Pohnpei to west of Wake

Island, extending north-northeast from near 7N157E to end near

20N165E. Scattered to numerous showers and isolated thunderstorms are

seen from Pohnpei to just north of Wake Island. Upper-level

divergence is helping to enhance this convection. The trough will

continue moving west over the next few days, with the northern

portion, north of 15N, splitting from the rest of the trough and

moving northwest.



The next three troughs are in close proximity of each other, with 

the first one seen east of Kosrae extending north-northeast from near

3N166E to near 8N168E. The second one is seen west of Butaritari to 

just east of Majuro, extending north-northeast from near 3N170E to 

10N174E. The third one is found east of the Marshall Islands 

extending north-northeast from near 3N178E to 7N180. These troughs 

are interacting with a developing ITCZ to produce scattered showers 

and isolated thunderstorms from near the Date Line across the 

Marshall Islands to Kosrae. All of the troughs will continue to move 

west, strengthening the convergence along the ITCZ.



TUTT...

A TUTT enters the area near 25N139E, extending south to a cell

centered near 22N139E, then continues south-southeast to end west of

Guam near 11N141E. Divergence west of the TUTT is interacting with 

the monsoon trough and a band of strong convergence north of the

monsoon trough to enhance convection across the Philippine Sea. The

TUTT cell is generating scattered to numerous showers well west and

southwest of Iwo To. The TUTT and cell will continue to drift west

over the next several days.



Another TUTT cell is seen to the northwest of Wake Island, centered

near 23N161E. The TUTT extends south from this cell to end near

13N161E. Scattered showers and isolated thunderstorms are found with

the cell. Divergence with the trough is enhancing convection along

an elongated trade-wind trough. The TUTT and cell look to remain 

quasi-stationary over the next few days.



OTHER SYSTEMS...

A band of strong convergence is found north of the monsoon trough

over the Philippine Sea. This convergence is interacting with the

TUTT to produce scattered to numerous showers across the Philippine

Sea between 130E and 135E. This convergence band looks to drift west,

out of the area, over the coming days.



...ITCZ...

The ITCZ stretches east from near 5N164E to beyond the Date Line near

6N. Three trade-wind troughs are interacting with the ITCZ to

generate scattered showers and isolated thunderstorms across Kosrae

and the Marshall Islands.



$$



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