WPAC: SINLAKU - Typhoon

[sasha_B]

This seems to be taking shape & getting organised now (DT 2.5 as far as I can tell, which could be enough for the JTWC to call it a TS by 18z). Could be named before too long, and the JMA is now predicting a 90 kt / 935 hPa peak on the 14th. There's pretty solid model consensus that this will be a major typhoon eventually.

[cycloneye]

A. 04W (NONAME)

B. 09/1130Z

C. 8.5N

D. 151.8E

E. THREE/HIMAWARI-9

F. T2.5/2.5

G. IR/EIR/PRXY

H. REMARKS...4.5/10 BANDING RESULTS IN A DT OF 2.5. MET IS 2.5 BASED
ON A DEVELOPING TREND. PT AGREES. THE FT IS BASED ON THE MET DUE TO
UNCERTAINTY IN CENTER LOCATION.

I. ADDL POSITIONS

NIL


...ZENG

[dexterlabio]

I think Mawar (2023) could be a decent analog to this system based on the models showing TD 04:


- Form just before a string El Niño.

- Directly impact Guam from the SW.

- Peak W of the Philippines before going out to sea.

- Have a large TS-force wind field.

Mawar is a May STY. Not exactly early season.

[cycloneye]

Hydrologic Outlook
National Weather Service Tiyan GU
1116 PM ChST Thu Apr 9 2026

...HEAVY RAINFALL PROBABLE FOR THE FIRST HALF OF NEXT WEEK...

Tropical Storm 04W, currently located north of Chuuk, continues to
organize and strengthen as it moves slowly west-northwest at 3
mph. This system is expected to become a tropical storm over the
next few hours, strengthening further the next few days. As we
approach the weekend, forward speed of 04W will increase, allowing
the leading edge of the system to start affecting the region by
Saturday afternoon. This rainfall will then increase in frequency
and intensity Sunday into Monday, and may continue through
Wednesday.

Current forecasts range from 10 to 15 inches across Guam,
decreasing into the 4 to 8 inch range for Saipan, with locally
higher amounts possible. Of course, this is all dependent on the
eventual track and intensity of what is expected to be a typhoon
or super typhoon as it passes through the region, with current
forecast tracks keeping the center a little south of Guam.
However, forecast uncertainty remains and further track changes
are anticipated.

NOW IS THE TIME TO START PREPARING for locally heavy rainfall and
the effects of such, especially if you live in or near a poor
drainage area. Please continue to monitor the forecasts for
changes at www.weather.gov/gum, or follow us on social media.

$$

Doll

[WaveBreaking]

I think Mawar (2023) could be a decent analog to this system based on the models showing TD 04:


- Form just before a string El Niño.

- Directly impact Guam from the SW.

- Peak W of the Philippines before going out to sea.

- Have a large TS-force wind field.

Mawar is a May STY. Not exactly early season.

Yeah, forgot to write down that the two formed a month apart so the climo would be different.

[cycloneye]

HAFS-A. No words to say here.

[cycloneye]

JTWC uo to 35kt. Dvorak up to 3.0.

04W FOUR 260409 1800 8.4N 151.6E WPAC 35 997




A. 04W (NONAME)

B. 09/1730Z

C. 8.6N

D. 151.1E

E. THREE/HIMAWARI-9

F. T3.0/3.0

G. IR/EIR/PRXY/GMI/AMSR2

H. REMARKS...6/10 BANDING RESULTS IN A DT OF 3.0. CONVECTIVE CLOUD TOPS
AS COLD AS -92 C. UPR-LVL OUTFLOW GOOD S-W-N QUADS. MET AND PT=3.0. FT
BASED ON MET DUE TO PULSING CONVECTION.

[cycloneye]

JMA upgrades to TS Sinlaku.

T2604(Sinlaku)
Issued at 2026/04/09 19:30 UTC
Analysis at 04/09 18 UTC
Grade TS
Scale -
Intensity -
Center position N8°25′ (8.4°)
E150°10′ (150.2°)
Direction and speed of movement W 20 km/h (10 kt)
Central pressure 996 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of 30-kt wind area NE440 km (240 NM)

[cycloneye]

[cycloneye]

 https://x.com/MichaelIgbino10/status/2042347286236139558



 https://x.com/MichaelIgbino10/status/2042347306368881110

[cycloneye]

Cat 5 from HAFS-A south of Guam.

[cycloneye]

A. 04W (SINLAKU)

B. 09/2330Z

C. 8.4N

D. 150.8E

E. THREE/HIMAWARI-9

F. T3.0/3.0

G. IR/EIR/VIS/SSMIS

H. REMARKS...6/10 BANDING RESULTS IN A DT OF 3.0. 1946Z SSMIS PASS
SHOWED EXCELLENT SPIRAL OUTER BANDING. CONVECTIVE CLOUD TOPS AS COLD AS
-95 C. UPR-LVL OUTFLOW IMPROVING ALQDS. MET AND PT=3.0. FT BASED ON MET
DUE TO PULSING CONVECTION.

[cycloneye]

[sasha_B]

The 18z HAFS-A run takes this to 903 hPa and 160 kt, between 0412/2100z and 0413/0300z. That's quite something for a forecast <96h out - this could be one to watch.

As for Sinlaku's current intensity, we're fortunate enough have recent scatterometer and MW imagery that (IMO) make it pretty clear she's not yet any stronger than 45 kt / 990 hPa. The JTWC's estimate of 40 kt / 994 hPa is equally reasonable; JMA has 45 kt (10-min., comparable to 50 kt 1-minute) and 990 hPa, which is perhaps a little aggressive but still justifiable considering the cloud pattern arguably supports T3.5.

[Hurricane2022]

Looks good

[cycloneye]

Special Weather Statement
National Weather Service Tiyan GU
1129 AM ChST Fri Apr 10 2026

GUZ001-MPZ001>003-110130-
Guam-Rota-Tinian-Saipan-
1129 AM ChST Fri Apr 10 2026

Tropical Storm Sinlaku (04W) continues to organize north-northwest of
Chuuk. This system will continue to move very slowly in a west to
northwest direction for another 24 to 36 hours, before increasing
forward speed as it strengthens. The current forecasts have the
system strengthening into a typhoon or stronger, and approaching the
Marianas. The potential track takes TS Sinlaku into the Marianas,
near Guam. However, models continue to show a slight spread where TS
Sinlaku`s track could shift slightly north or south, though these
ranges are narrowing and will continue to narrow over the next 12-24
hours.

A breezy, but relatively dry trade-wind pattern is in place over the
Marianas, but as Tropical Storm Sinlaku closes in, conditions will
deteriorate sometime around late Sunday. The Marianas should make
preparations for the potential for Tropical Storm or Typhoon-Force
winds, with the most likely time of Tropical Storm-Forced winds
around Monday. For the far northern Mariana Islands, breezy and
choppy sea conditions are expected late this weekend and inter early
next week, with potential for Tropical Storm-Force winds around
Tuesday.

Locally heavy rainfall is likely with Tropical Storm Sinlaku.
Models show the potential 10 to 15 inches near the center of TS
Sinlaku, but if any of the islands will see this rainfall will
depend on exact track of TS Sinlaku. Ensemble guidance shows broader
potential for 5-8 inches across Guam, and 3-5 inches for Rota,
Tinian, and Saipan, but higher rainfall totals may shift depending if
the track of Tropical Storm Sinlaku shifts southward or northward.
of rainfall to develop for Guam early next week

$$

Schank

[mrbagyo]

[cycloneye]

Latest JTWC track is thru Guam as cat 3.

[cycloneye]

https://s13.gifyu.com/images/bqEx1.gif

About to takeoff bigtime.

[cycloneye]

FORECAST DISCUSSION: THE FORECAST TRACK HAS CHANGED LITTLE FROM
THAT IN THE PREVIOUS WARNING, SHIFTING SLIGHTLY TO THE SOUTH AT TAU
96 AND TAU 120. THE STEERING ENVIRONMENT IS DICTATED BY A NER TO
THE EAST THAT WILL COMPETE WITH A STRONG STR TO THE NORTHWEST, WITH
A WEAKNESS IN THE RIDGE TO THE NORTH OF THE SYSTEM. THE INFLUENCE
OF THESE COMPETING FEATURES WILL YIELD A SLOW TRACK TOWARDS THE
NORTHWEST THROUGH TAU 36. TS 04W WILL GAIN FORWARD SPEED BY TAU 48
AS THE NER BUILDS TO THE EAST, AND THE FASTER MOVEMENT WILL
CONTINUE TO THE END OF THE FORECAST PERIOD. THE UNCERTAINTY IN THE
EVOLUTION OF THE RIDGES LENDS TO LOW CONFIDENCE IN THE FORECAST
TRACK. GIVEN THE LARGELY FAVORABLE ENVIRONMENTAL CONDITIONS, THE
SYSTEM WILL CONTINUE TO INTENSIFY AT NEAR THE CLIMATOLOGICAL RATE
THROUGH TAU 24. RAPID INTENSIFICATION IN THE SHORT TERM IS LESS
LIKELY BECAUSE THE LARGE SYSTEM IN THE FACE OF SOME VWS ALOFT WILL
NECESSITATE A PERIOD OF TIME TO WORK OUT THE ASYMMETRIES IN THE
NASCENT INNER CORE. HOWEVER, ONCE THE INNER CORE BECOMES SYMMETRIC,
TS 04W WILL UNDERGO A HIGHER RATE OF INTENSIFICATION. WHILE THE
CURRENT FORECAST SHOWS A 25 KT INCREASE IN 24 HOURS, WHICH IS JUST
SHY OF RAPID INTENSIFICATION (RI), AND A PEAK OF 110 KTS, IT IS NOT
OUT OF THE QUESTION THAT THE SYSTEM COULD INTENSIFY FASTER AND
REACH A HIGHER PEAK PRIOR TO REACHING GUAM. TOWARDS THE END OF
FORECAST PERIOD, A MODERATION OF INTENSITY IS INDICATED AS THE
SYSTEM COULD UNDERGO AN EYEWALL REPLACEMENT CYCLE AND APPROACH ITS
MAXIMUM POTENTIAL INTENSITY.

MODEL DISCUSSION: THE CROSS-TRACK SPREAD HAS NARROWED SLIGHTLY TO
300 NM AT TAU 96 AND 400 NM AT TAU 120, WITH THE GFS AND GEFS MEAN
TRACKERS SHIFTING NORTHWARD AND CLOSER TO GUAM BUT REMAINING ON THE
SOUTHWESTERN EDGE OF THE GUIDANCE ENVELOPE. THE ECMWF HAS SHIFTED
SLIGHTLY CLOSER TO GUAM AS WELL AND LIES VERY CLOSE TO THE CONSENSUS
MEAN AND THE ECMWF ENSEMBLE MEAN. THE FORECAST TRACK IS PLACED ALONG
THE GROUPING OF THESE MODELS AND IS VIRTUALLY UNCHANGED THROUGH TAU
72. THE TRACK IS SHIFTED SLIGHTLY TO THE SOUTH AT TAU 96 AND TAU 120,
PRIMARILY DUE TO THE HAFS-A AND HWRF MESOSCALE MODELS SHIFTING
SOUTHWARD AND THE EXPERIMENTAL AI MODELS SHIFTING CLOSER TO GUAM.
OVERALL, CONFIDENCE REMAINS LOW THROUGH THE FORECAST PERIOD. THE
FORECAST INTENSITY FOLLOWS THE CONSENSUS THROUGH TAU 24 AT THE
CLIMATOLOGICAL RATE AND THEN HEDGES CLOSER TO THE HAFS-A OUTPUT
DEPICTING A FASTER RATE OF DEVELOPMENT. THE PEAK INTENSITY OF 110 KTS
IS ON THE HIGHER END OF THE MODEL SUITE BUT STILL LOWER THAN
THE 125 KTS DEPICTED BY HAFS-A AT TAU 72.

FORECAST CONFIDENCE:
TRACK 00-72 HR: LOW
TRACK 72-120 HR: LOW
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//