WPAC: SINLAKU - Typhoon

[Hayabusa]

Been a while that JMA upgraded at intermediate synoptic time

WTPQ50 ‎RJTD ‎100900
RSMC ‎TROPICAL ‎CYCLONE ‎ADVISORY
NAME ‎ ‎STS ‎2604 ‎SINLAKU ‎(2604) ‎UPGRADED ‎FROM ‎TS
ANALYSIS
PSTN ‎ ‎100900UTC ‎08.1N ‎150.6E ‎GOOD
MOVE ‎ ‎NW ‎SLOWLY
PRES ‎ ‎985HPA
MXWD ‎ ‎050KT
GUST ‎ ‎070KT
30KT ‎ ‎270NM ‎NORTHEAST ‎210NM ‎SOUTHWEST
FORECAST
24HF ‎ ‎110900UTC ‎09.0N ‎150.3E ‎50NM ‎70%
MOVE ‎ ‎ALMOST ‎STATIONARY
PRES ‎ ‎975HPA
MXWD ‎ ‎060KT
GUST ‎ ‎085KT
45HF ‎ ‎120600UTC ‎10.2N ‎148.3E ‎85NM ‎70%
MOVE ‎ ‎NW ‎06KT
PRES ‎ ‎950HPA
MXWD ‎ ‎080KT
GUST ‎ ‎115KT
69HF ‎ ‎130600UTC ‎11.9N ‎145.3E ‎120NM ‎70%
MOVE ‎ ‎WNW ‎09KT
PRES ‎ ‎920HPA
MXWD ‎ ‎100KT
GUST ‎ ‎140KT
93HF ‎ ‎140600UTC ‎13.7N ‎142.7E ‎150NM ‎70%
MOVE ‎ ‎NW ‎08KT
PRES ‎ ‎920HPA
MXWD ‎ ‎100KT
GUST ‎ ‎140KT
117HF ‎ ‎150600UTC ‎15.3N ‎141.2E ‎180NM ‎70%
MOVE ‎ ‎NW ‎SLOWLY
PRES ‎ ‎920HPA
MXWD ‎ ‎100KT
GUST ‎ ‎140KT ‎=

[mrbagyo]

METAR: PTKK 101050Z 19020G35KT 12SM -SHRA SCT010CB OVC110 27/25 A2921 RMK CB ALQDS MOV N SLP893 T02690250

Chuuk reporting 989.3 hPa mslp
Sustained south wind of 20 knots gusting to 35 knots

[Hayabusa]

Euro 06z

[Teban54]

Euro 06z
https://i.imgur.com/yqPoTnO.png

When was the last time that operational Euro, not EC-AI, explicitly forecasted a sub-900 storm? Can't remember this happening very often, even for Melissa etc.

[xtyphooncyclonex]

I remember the Euro going sub-900 during Typhoon Dolphin in 2015, similar trajectory too. Ended up missing the nuts model runs, but still became a category five anyway in a Super El Niño year.

Correction: It was Atsani. The GFS bombed out Dolphin.

The Euro also went really bullish on Ragasa.

[cycloneye]

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
EXPANDING CENTRAL DENSE OVERCAST (CDO) AND A VORTEX THAT IS
BECOMING VERTICALLY ALIGNED. SINCE 100800Z AND DURING THE DIURNAL
MINIMUM, CONVECTION HAS EXPLODED OVER THE EASTERN PERIPHERY OF THE
CDO, WITH OVERSHOOTING CLOUD TOPS MEASURING -97 DEGREES CELSIUS AND
A DEFINED GRAVITY WAVE PROPAGATING THROUGH THE NORTHEAST QUADRANT.
MEANWHILE, A 100800Z WSF-M MWI PASS REVEALED A CLOSED LOWER-LEVEL
INNER CORE. A 101350Z METAR FROM CHUUK MEASURED A WIND GUST OF 48
KTS AND A MEAN SEA-LEVEL PRESSURE OF 986.8 MB. THE EXPANDING
OVERCAST IN THE UPSHEAR SIDE OF THE CIRCULATION INDICATES THAT THE
SYSTEM IS ABLE TO RESIST THE EFFECTS OF MODERATE, SOUTHEASTERLY
VERTICAL WIND SHEAR. ENVIRONMENTAL ANALYSES REVEAL FAVORABLE
CONDITIONS FOR INTENSIFICATION, CHARACTERIZED BY WARM SEA SURFACE
TEMPERATURES (SST), ABUNDANT DEEP-LAYER MOISTURE AS EVIDENCED BY
THE 101200Z CHUUK ATMOSPHERIC SOUNDING, AND ROBUST POLEWARD
OUTFLOW. WHILE A PARTIAL 101124Z ASCAT-B PASS STILL DEPICTS SOME
ASYMMETRIES IN THE SURFACE WIND FIELD, THE AFOREMENTIONED FACTORS
AND DEVELOPMENT TRENDS INDICATE THAT TS 04W IS PRIMED FOR A MORE
RAPID RATE OF INTENSIFICATION. THE INITIAL INTENSITY IS SET AT 55
KTS WITH HIGH CONFIDENCE BASED ON THE UNANIMOUS T3.5 DVORAK
ESTIMATES FROM PGTW, KNES, RJTD, AND RCTP. THE INITIAL POSITION IS
PLACED WITH LOW CONFIDENCE WITH SUPPORT FROM THE ASCAT PASS AND THE
SURFACE OBSERVATION AT CHUUK. THE MAXIMUM SIGNIFICANT WAVE HEIGHT
HAS BEEN REDUCED DUE A TEMPORARY CONTRACTION OF THE EXTENT OF
GALE-FORCE WINDS OVER THE NORTHERN SEMICIRCLE AS THE SYSTEM WORKS
OUT ITS ASYMMETRIES.

INITIAL WIND RADII BASIS: PARTIAL SCATTEROMETER DATA

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT WITH A
NEAR-EQUATORIAL RIDGE (NER) TO THE EAST AND A STRONG SUBTROPICAL
RIDGE (STR) TO THE NORTHWEST

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.5 - 55 KTS
RJTD: T3.5 - 55 KTS
RCTP: T3.5 - 55 KTS
KNES: T3.5 - 55 KTS
CIMSS ADT: 55 KTS AT 101140Z
CIMSS AIDT: 45 KTS AT 101140Z
CIMSS D-MINT: 45 KTS AT 100800Z
CIMSS D-PRINT: 54 KTS AT 101140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 15-20 KTS
SST: 28-29 CELSIUS
OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: LOCATED WITHIN A VERY WEAK STEERING
ENVIRONMENT WITH A NER TO THE EAST AND A STRONG STR TO THE
NORTHWEST, TS 04W IS QUASISTATIONARY WITH AN ESTIMATED WESTWARD
MOTION OF 2-3 KTS OVER THE PAST 12 HOURS. A TURN TOWARDS THE
NORTH-NORTHWEST IS ANTICIPATED OVER THE NEXT 12-18 HOURS AS THE NER
STRENGTHENS. AS THIS HAPPENS, THE STR WILL WEAKEN AND RETREAT
WESTWARD, WHICH WILL INDUCE A FASTER RATE OF TRAVEL TOWARDS THE
NORTHWEST FOR THE REMAINDER OF THE FORECAST PERIOD. TS 04W WILL
MAKE A DANGEROUSLY CLOSE APPROACH TO GUAM, AND IT APPEARS
INCREASINGLY LIKELY TO PASS SOUTH OF GUAM OR OVER THE SOUTHERN TIP.
HOWEVER, THE MORE NORTHERN ISLANDS OF ROTA, TINIAN, AND SAIPAN ARE
WITHIN THE UNCERTAINTY ENVELOPE. WARM SST, PLENTIFUL MID-LEVEL
MOISTURE, AND MODEST UPPER-LEVEL DIVERGENCE WILL FUEL CONTINUED
INTENSIFICATION AS TS 04W APPROACHES THE MARIANA ISLANDS. WITH
IMPROVING CONVECTIVE STRUCTURE, THE FORECAST CALLS FOR A
CLIMATOLOGICAL RATE OF DEVELOPMENT FOR THE FIRST 12 HOURS AND
EXPLICIT RI FROM TAU 12 TO TAU 48, ENABLING THE STORM TO REACH AT
LEAST 115 KTS AT TAU 72. AFTER PASSING GUAM, INTERNAL STRUCTURAL
CHANGES SUCH AS AN EYEWALL REPLACEMENT CYCLE AND AN EXPANSION OF
THE EYE WILL LIMIT FURTHER DEVELOPMENT.

[mrbagyo]

[cycloneye]

 https://x.com/cjfieldswx/status/2042638039466287329

[cycloneye]

Surface observations.

[sasha_B]

Surface observations.

https://i.imgur.com/ed7bUw3.gif

Based on that pressure reading at some distance from the center, this is clearly more intense now than the 986 hPa estimated at 12z. Probably up to around 60 kt right now.

[cycloneye]

 https://x.com/AndyHazelton/status/2042662207599579260

[ljmac75]

The DeepMind has kinda trended a little closer to the NMI the last few runs, decent cluster near Guam, although also a lot of members far way from Guam. I think the lack of actual movement by the storm has been giving it some trouble though.

[Hurricane2022]

 https://x.com/i/status/2042667646408364210

[cycloneye]

4.0

A. 04W (SINLAKU)

B. 10/1730Z

C. 8.0N

D. 151.1E

E. THREE/HIMAWARI-9

F. T4.0/4.0

G. IR/EIR/PRXY

H. REMARKS...9/10W BANDING RESULTS IN A DT OF 4.0. CDO TOPS AS COLD AS
-95 C. UPR-LVL OUTFLOW GOOD ALQDS. MET AND PT=4.0. FT BASED ON MET DUE
TO PULSING CONVECTION.

I. ADDL POSITIONS

NIL


...KONON

[cycloneye]

JMA upgrades to typhoon.

T2604(Sinlaku)
Issued at 2026/04/10 18:45 UTC
Analysis at 04/10 18 UTC
Grade TY
Scale -
Intensity -
Center position N8°00′ (8.0°)
E151°20′ (151.3°)
Direction and speed of movement Almost stationary
Central pressure 975 hPa
Maximum sustained wind speed near center 35 m/s (65 kt)
Maximum wind gust speed 50 m/s (95 kt)
Radius of 50-kt wind area 95 km (50 NM)

[Hurricane2022]

Thinking this may go pinhole soon. Surigae's record of strongest pre-May typhoon could be in trouble rn.

[sasha_B]

Thinking this may go pinhole soon. Surigae's record of strongest pre-May typhoon could be in trouble rn.

In recent VIS frames (2027z～2127z) there does seem to be an eye forming near or just north of where the JTWC's 21z satellite bulletin fixed the center. Matching Surigae would be a very tall order, though - there's little model support at the moment for Sinlaku reaching 140 kt, let alone 170 kt.

That said, based on that same satellite fix...

H. REMARKS: 28A/PBO LRG CDO/ANMTN. WELL-DEFINED CDO OF 105NM IN
DIAMETER YIELDS A CF OF 4.0. ADDED 0.5 FOR BF TO YIELD A DT OF 4.5.
MET YIELDS 3.5. PT YIELDS 4.0. DBO DT.

...she does seem to be intensifying ahead of schedule.

[ljmac75]

I think there was a microwave scan that showed a good core forming but I can't find it now so I might have imagined it.

[sasha_B]

I think there was a microwave scan that showed a good core forming but I can't find it now so I might have imagined it.

I could've sworn I saw that one too, but I can't seem to find it now, either. Odd. For what it's worth, UW-CIMSS ADT has indeed switched over to the "MW Eye" pattern, based on SSMISF17 imagery:

20260410 193245 SSMISF17 8.1 151.4 57 88% 16.00 31.00 >65 kts 60.0 8.1 151.0

Based on a subjective CI of 4.5 and the fact that ADT more or less agrees (CI 4.4), there's a strong argument to be made that Typhoon Sinlaku is around 75 kt and between 970～975 hPa at time of writing.

[Yellow Evan]

Well on its way to significant intensification with shear likely to subside tomorrow and with microwave already showing a mid level inner core.

Edit: The MW in question.