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Tropical Weather Discussion...UPDATED
National Weather Service Tiyan GU
455 PM ChST Sun Aug 9 2026

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...

Updated for changes in tropical  section.

TROPICAL AND MONSOON DISTURBANCES...
Updated text: This product is being updated for the Joint Typhoon
Warning Center`s re-issuance of advisories for Tropical Depression
13W (Kujira) and a Tropical Cyclone Formation Alert (TCFA) for Invest
98W.

Tropical Depression 13W (Kujira) is currently located at 22N142E and
is moving east-southeast at 10 mph. No direct impacts are expected
across the CNMI, but heavy rainfall will be possible across the far
the northern Marianas.

Invest 98W is now subject to a TCFA by the JTWC. This means that
tropical cyclone development is likely within 24 hours. Invest 98W
will move off the northeast and will exit our Area of Responsibility
(AoR) over the coming days.

Previous text:
Today we have a "flurry of activity", as we now have three
invests or remnant systems, and a fourth we`re watching. First up
are the remnants of TD 13W (Kujira). These remnants are now the
subject of a TCFA from JTWC, which is currently located near
23N141E. This will likely strengthen further back to a tropical
depression within the next 24 hours, as evident by the TCFA,
recent satellite imagery, and model forecasts. It`s then expected
to head east-southeast towards the Maug Islands in the northern-
most CNMI, before curving back to a northeast heading, as it heads
towards an area north of Wake Island in the next few days.

Next on the list is Invest 98W, currently 300 miles east-
northeast of the Maug Islands, as it`s currently near 20N153E.
This disturbance is rated as "Medium" by JTWC, meaning development
of a tropical cyclone is likely beyond 24 hours. Conditions are
favorable for both the TCFA and 98W to continue to organize, and
the models also show this will occur with 98W as it also heads for
an area north of Wake Island during the next few days.

Then we have another circulation, dubbed invest 99W, which is
located near along the monsoon trough near 22N166E. This
disturbance lacks a true LLCC per scatterometer analysis and
visible imagery loops. This looks to be more an artifact of a
monsoon vortex co-located at the end of a monsoon trough and
within a favorable environment, with no development expected.
Still, given sharp bending in the streamline analysis and some
localized elevated convection, the "Sub-Low" rating from JTWC is
warranted, and we`ll keep an eye on it.

Finally, we have an area of cyclonic rotation that we`ve been
watching for a few days now, northeast of Majuro near 10N173E. The
cyclonic low-level flow around the LLCC has strengthened markedly
since yesterday, as evident in the visible loop imagery. This
circulation is at the tail end monsoon trough. The increased
cyclonic flow has allowed for convection to increase from near
Kosrae to Majuro, as westerly flow south of the LLCC has
strengthened. With that said, we still expect this system to head
west to the RMI chain with a steady state in development, before
possibly drifting west-southwest to east of Pohnpei/north of
Kosrae while it weakens, with this expected to occur over the next
48 to 72 hours. With that said, JTWC and WFO Guam continue to
watch this feature for possible Invest inclusion.

For more information please refer to bulletins from the Joint
Typhoon Warning Center under WMO header ABPW10 PGTW.

...OTHER WEATHER SYSTEMS...

MONSOON TROUGH...
The monsoon trough has strengthened temporarily, as increased,
localized southwesterly flow around the LLCC remnants of TD 13W
and Invest 98W help augment the pattern. with this in mind, the
monsoon trough looks to remain anchored near its current
position, with the main belt of west to southwest winds centered
between 10N and 22N from 130E to 165E. This looks to continue the
next few days, as a "carousel" of disturbances may develop given
the warm SSTs, low vertical wind shear, and from a pattern
recognition viewpoint. The tail end of the trough that links up
with the Majuro circulation should also remain in place as
additional energy crosses the Date Line, while sinking a little
south in Latitude, perhaps, as we head through the first half of
this week.

$$

Doll