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AXPQ20 PGUM 082200

TWDPQ 



Tropical Weather Discussion

National Weather Service Tiyan GU

800 AM ChST Fri Jun 9 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...



TROPICAL CYCLONES...

At 7 am ChST, Typhoon Guchol was centered 740 miles northwest of Yap,

near 17.1N and 130.3E. Guchol has managed to wrap convection all the

way around the center now, however the west side remains weaker than

the east. Monsoonal showers are found south and east of Guchol from

10N to 19N and 130E to 136E.



For more information please refer to bulletins from the Joint

Typhoon Warning Center under WMO header WTPN31 PGTW and from the

National Weather Service under WMO header WTPQ31 PGUM.



...OTHER WEATHER SYSTEMS...



MONSOON TROUGH...

The monsoon trough runs from north of Luzon to 17N130E to Typhoon

Guchol to 12N140E to 8N147E, where it transitions to a surface trough

then reaches toward a weak circulation near 5N151E. Another trough

then stretches east-northeastward to 8N158E. In addition to the

showers mentioned above with Typhoon Guchol, the monsoon trough is

generating scattered showers and isolated thunderstorms between 6N and

10N from 130E to 138E, which includes Koror, Palau and is just west of

Yap. The circulation and eastern trough are spreading scattered

showers and isolated thunderstorms from 1N to 9N from 150E to 162E.



TRADE-WIND TROUGHS...

A vigorous trade-wind trough runs through the southern Marshall

Islands, along Majuro's longitude, from the equator to 9N. This

feature is spraying scattered showers and isolated thunderstorms

across a wide area from the equator to 6N between 164E and 175E.

Between 170E and 173E numerous showers and scattered thunderstorms

are found.



Another trade-wind trough cuts from 12N144E to 15N148E to 25N148E. In

combination with the TUTT it is producing scattered showers and

isolated thunderstorms within 180 miles of a line from 12N148E to

22N152E to 24N147E. This is east of the Mariana Islands.



TUTT...

The Tropical Upper Tropospheric Trough (TUTT) extends from an upper-

level low east of the date line to 19N180 to an upper-level low near

18N171E to around 25N166E. An older segment which was interrupted is

found associated with an upper-level low near 19N146E. The eastern

portion is producing weak convection with extensive cloudiness and

scattered showers in the northern Marshall Islands. The western

segment is lighting up the showers of the trade-wind trough and

turning them into thunderstorms from 4N to 24N between 146E and 154E.



...DISCUSSION...

Typhoon Guchol is expected to recurve at the very edge of Micronesia.

If it does so, we could be issuing advisories for another day or two

at least. If it delays, we could end up stopping, and perhaps even

restarting if it then strays to the east of 130 again before going

north of 25N. Interesting times. The main influence on Micronesia that

Guchol has now is swell.



The monsoon trough will generally follow along with Guchol. It has

lifted far enough north of Palau and Yap that the heavier weather is

now north of them, and it should continue to lift further north. The

monsoon trough does not currently extend far enough east to affect

Chuuk, and looks like it will have trouble getting far enough north to

affect the Marianas. Nevertheless, this has been quite impressive for

late May and early June, so we need to keep our eyes open this year.



The trade-wind troughs will move westward, with the one near Majuro

beginning to affect Kosrae, and the one east of the Marianas beginning

to affect the Marianas.



The TUTT has been disrupted and will remain weakened for the next few

days. Since this is TUTT season, it will likely strengthen again by

early next week.



$$



Stanko