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AXPQ20 PGUM 112123

TWDPQ 



Tropical Weather Discussion

National Weather Service Tiyan GU

723 AM ChST Mon Jun 12 2023



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.



...SIGNIFICANT/SPECIAL FEATURES...



None.



...OTHER WEATHER SYSTEMS...



MONSOON TROUGH...

The monsoon trough extends from north of Luzon to 25N130E to Typhoon

Guchol near 26N135E and farther northeast. The monsoon trough is

creating scattered showers and isolated thunderstorms within 120 miles

of a line from 15N130E to 23N139E. This is well north of Palau and

Yap. In areas just south of Typhoon Guchol, the monsoon trough is

producing strong to near gale winds and rough seas.



TRADE-WIND TROUGHS...

A trade-wind trough curves from EQ137E to 12N145E to 21N145E to

25N148E. This trough is generating scattered showers and isolated

thunderstorms across a broad region between the equator and 8N from

132E to 147E, and between 8N and 16N from 143E to 146E. This includes

much of the Republic of Palau and Yap State, as well as the Marianas

from Saipan southward.



A second trade-wind trough stretches from EQ169E to 6N166E. This

trough is producing scattered showers and isolated thunderstorms

between the equator and 8N from 165E to 180, including many of the

atolls in the Marshall Islands.



TUTT...

The Tropical Upper Tropospheric Trough (TUTT) reaches from east of the

date line to 22N180 to an upper-level low near 18N167E to 15N160E.

The TUTT is producing a band of enhanced mid-level cloudiness within

120 miles of a line from 10N157E to 10N162E to 18N173E.



...DISCUSSION...

The monsoon trough will gradually weaken as Typhoon Guchol begins

extratropical transition. At some point, it will likely snap back to

the south and begin incubating another tropical cyclone or two. It

doesn't look like that will happen this week, but it probably won't be

that long after. We're headed into the heart of Tropical Cyclone

season.



The trade-wind troughs are expected to continue to head westward with

little change in strength, although some change in geometry is

possible, as we had 2 troughs merge yesterday. The one east of Yap and

near the Marianas will affect the Marianas this morning and tonight,

and will affect Yap tonight through Tuesday night. The one currently

near the Marshalls will begin to affect Kosrae tonight through Tuesday

night.



The TUTT has apparently weakened since yesterday, or at least the

convection has. Little change is expected the next day or two, then

both the GFS and the ECMWF-HiRes indicate some gradual weakening.



$$



Stanko