296
AXPQ20 PGUM 220103
TWDPQ

Tropical Weather Discussion
National Weather Service Tiyan GU
1103 AM ChST Sun Sep 22 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.

TROPICAL DISTURBANCES...
An area of heavy showers and thunderstorms can be seen east-
southeast of the Marianas near 12N154E, designated as Invest 91W
by the JTWC. Moderate to strong convection has been flaring up
within the system`s east and northwest flanks since the early
morning hours, and evidence of a weak surface circulation can be
seen in Himawari visible satellite data. GLD network data has
shown occasional to frequent lightning, especially within the
thunderstorms flanking the eastern side. 91W has been moving
swiftly west-northwest this morning and remains poorly organized.
Latest model guidance indicates the system will slow down as it
meanders toward the Marianas over the next few days, arriving
sometime Tuesday night or Wednesday morning with only moderate to
fresh winds expected at this time. 91W will be closely monitored,
but is currently not favored to develop into a significant
tropical cyclone before it crosses the Marianas.

Another surface circulation can be seen within a broad trade-wind
trough farther east, to the northeast of Majuro and southeast of
Wake Island near 13N174E. Scattered showers and isolated
thunderstorms are seen associated with this circulation, with some
enhancement from a TUTT located to the northwest which will be
discussed further below. Model guidance indicates the weak
circulation will open up as a diminished surface trough, crossing
the northern Marshall Islands over the next day or two.

...OTHER WEATHER SYSTEMS...

TRADE WIND TROUGHS...
The aforementioned trade-wind trough is seen to the northeast of
Majuro, stretching northeast from near 10N169E and continuing
through the Date Line at around 18N. Scattered showers and
isolated thunderstorms are located along the trough`s axis,
enhanced by upper-level divergence associated with the TUTT to the
northwest. The trough will move over the Marshall Islands and into
central Micronesia over the next few days increasing showers near
Kosrae and Pohnpei, and then later Chuuk by mid-week.

TUTT...
TUTT cells are seen south and east of Wake Island near 16N164E and
23N178E. The TUTT stretches southeast from near 25N155E through
the first TUTT cell, continuing northeast through the second cell
before exiting the AOR near 25N180. The TUTT is interacting with
the aforementioned broad trade-wind trough to produce showers and
thunderstorms just northeast of the RMI. The TUTT will gradually
consolidate into one cell, shifting west over the coming days to
reposition near the Marianas by Friday, where it may interact with
a surface trough to increase showers and thunderstorms across the
area by the weekend.

$$

DeCou