619
AXPQ20 PGUM 170049
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1049 AM ChST Mon Jun 17 2024

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...

SURFACE TROUGH...
A surface trough still extends into the region from the Philippines,
but it has shifted southward slightly entering the region near
6N130E and passes south of Palau as it continues to EQ140E.
Scattered to numerous showers and isolated thunderstorms extend
along the trough, especially from Palau through Yap State, between
the equator and 12N due to the increased convergence created by the
trade winds and ITCZ pushing back into western Micronesia from Chuuk.
The surface trough looks to linger in far western Micronesia, though
it may retreat slightly westward towards 130E as the trade- winds
push further into western Micronesia and the surface trough struggles
to extend westward to southeast Asia, as Palau and Yap remain in
this early transitional phase of the summer monsoon pattern.
Expecting convergence created by the surface trough and trade winds
will keep scattered showers and isolated thunderstorms around Palau
and western Yap State over the next couple of days.

TUTT...
There are still two TUTT lows in the northern sections of the
region. The first low is well northwest of the Marianas near 24N135E
as it continues to move northward and should exit our region in the
next 24 hours. The second TUTT low started to interact with an upper-
level trough in the mid-latitudes to the north, so instead of
continuing on its northwest drift towards Wake Island, it was
actually pulled north-northeast and is now located east of Wake
Island near 21N176E. Models show this TUTT low breaking free of the
mid-latitude trough and drifting over Wake Island later in the week.
Convection is very limited around both TUTTs with the Global
Lightning Detection (GLD) network detecting a few lightning strikes
from isolated thunderstorms south of the first low. Satellite
imagery shows extensive mid-level and upper-level cloud cover
wrapping around the lower half of the low northwest of the Marianas,
while the TUTT east of Wake Island has some mid-level to upper-level
clouds to the east of the low, but most of the cloud cover located
northwest of the low as it interacts with a decaying cold front just
north of 25N.

...ITCZ...
The ITCZ has rebuilt across eastern and central Micronesia extending
from across the Date Line and through the Marshall Islands, Kosrae,
Pohnpei, and Chuuk, and ending in eastern Yap State, south of Guam,
as it pushes against the surface trough mentioned above. The ITCZ is
producing scattered to numerous showers and isolated thunderstorms
across the region mainly between 2N and 8N east of Chuuk Lagoon, and
then extending up to 12N, south of Guam`s coastal waters, west of
Chuuk Lagoon. North of the ITCZ a drier trade-wind pattern extends
across the Marianas and up to Wake Island. Model guidance suggest the
ITCZ will start to fragment into a series of trade-wind troughs
Tuesday or Wednesday as the ITCZ looses it southeast winds and the
northeast trade winds become the primary winds north of the equator.
The troughs will continue to produce scattered showers and isolated
thunderstorms across the region, but showers will be more concentrated
near the troughs and weak trade-wind convergence that usually
develops near troughs.

$$

Schank