WESTERN PACIFIC: Typhoon 04W(SINLAKU) large and still powerful CAT 3 US, slow mover lead to a prolonged period period of destructive winds over the MARIANAS/ SOUTH INDIAN: Invest 92S//150900 UTC

WDPN31 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0N 144.9E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 71 NM NORTHWEST OF SAIPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE,
POWERFUL TYPHOON SLOWLY TRACKING AWAY FROM SAIPAN AND TINIAN. THE
4-5 KT FORWARD SPEED HAS LED TO A PROLONGED PERIOD OF DESTRUCTIVE
WINDS OVER THE MARIANA ISLANDS. DEEP CONVECTION ASSOCIATED WITH THE
CENTRAL DENSE OVERCAST (CDO) CONTINUES TO ROTATE AROUND A LARGE
EYE. HAVING COMPLETED AN EYEWALL REPLACEMENT CYCLE (ERC), THE EYE
HAS ENLARGED TO 30 NM IN DIAMETER, AND THE WIND FIELD HAS EXPANDED.
A 142053Z WSF-M MWI 37 GHZ IMAGE SHOWED AN EYEWALL SLIGHTLY OPEN ON
THE NORTHERN SIDE WITH AN EVEN LARGER OUTER RING MEASURING 100-110
NM IN DIAMETER, WHICH SIGNIFIES POTENTIAL FOR ANOTHER ERC. A
COINCIDENT 142003Z RCM-3 SAR PASS REVEALED A SIMILAR STRUCTURE WITH
A 110 KT AVERAGE PEAK WIND. IN FACT, THE CIMSS MPERC PRODUCT
CAPTURES THIS STRUCTURE AND PREDICTS A 77 PERCENT PROBABILITY OF 
ANOTHER ERC. IN THE PAST 06 HOURS, TY 04W HAS BEEN ATTEMPTING TO
CONSOLIDATE ITS INNER CORE AS THE SURROUNDING CLOUD TOPS COOL, AND
THE UPPER-LEVEL OUTFLOW EXPANDS RADIALLY. BASED ON THIS TREND, THE
INITIAL INTENSITY IS HELD AT 110 KTS WITH MEDIUM CONFIDENCE AND IS
CONGRUENT WITH THE AGENCY DVORAK ESTIMATES RANGING FROM T5.5 TO
T6.5 AND THE CIMSS SATCON. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE WELL-DEFINED, CIRCULAR EYE ON THE MSI.
THE 34 KT WIND RADII WAS EXPANDED IN THE SOUTHWEST QUADRANT TO
ACCOUNT FOR THE GALE-FORCE WINDS STILL OBSERVED IN GUAM.
ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS OF WARM SEA
SURFACE TEMPERATURES, PLENTIFUL MID-LEVEL MOISTURE, AND LOW
VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: NORTHERN EXTENSION OF THE
NEAR-EQUATORIAL RIDGE TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.5 - 127 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 114 KTS AT 150600Z
   CIMSS ADT: 97 KTS AT 150530Z
   CIMSS AIDT: 99 KTS AT 150630Z
   CIMSS D-PRINT: 102 KTS AT 150630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE PRIMARY DRIVING MECHANISM FOR TY 04W IS
THE NORTHERN EXTENSION OF A NER. THE RIDGE WILL PINCH OFF FROM THE
NER AND BUILD, WHICH WILL STEER THE SYSTEM NORTHWARD THROUGH TAU
24. FOR THE REMAINDER OF THE FORECAST PERIOD, THE MID-LATITUDE
WESTERLIES WILL INCREASINGLY IMPART A FORCE TOWARDS THE EAST,
CAUSING THE STORM TO CURVE AND ACCELERATE NORTH-NORTHEAST FROM TAU
24 TO TAU 72 AND NORTHEAST TO EAST-NORTHEAST TOWARDS THE END OF THE
PERIOD. THE INTENSITY FORECAST FOR THE FIRST 24 HOURS HAS BEEN
ADJUSTED UPWARD. NOW THAT SINLAKU HAS COMPLETED ERC, THE FAVORABLE
ENVIRONMENTAL CONDITIONS WILL HELP MAINTAIN THE INTENSITY. IF A
SECOND ERC COMMENCES, IT WOULD SUPPORT CAPPING THE INTENSITY AND
POTENTIALLY INDUCE A SLOW WEAKENING TREND. THE INTENSITY FORECAST
CAPTURES THIS BY HOLDING THE INTENSITY STEADY THROUGH TAU 12 AND
THEN SHOWS SLOW WEAKENING AT TAU 24. TY 04W WILL WEAKEN MORE
QUICKLY BETWEEN TAU 24 AND TAU 48 AS IT ENCOUNTERS COOLER WATERS,
BECOMES SURROUNDED BY DRIER AIR, AND ENTERTAINS STRONGER POTENTIAL
FOR DRY AIR ENTRAINMENT DUE TO A SECOND ERC. RAPID WEAKENING WILL
TAKE PLACE AFTER TAU 48 ONCE THE SYSTEM TRAVELS OVER SUB-26 DEGREE
CELSIUS SST, AND THE VWS ASSOCIATED WITH THE WESTERLIES INCREASES
TO 20-30 KTS. EXTRATROPICAL TRANSITION (ETT) WILL BEGIN AT TAU 72.
NEVERTHELESS, THE FORECAST CALLS FOR A POTENT, STORM-FORCE
EXTRATROPICAL LOW AT TAU 120.

MODEL DISCUSSION: MODELS ARE IN FAIR AGREEMENT WITH A CROSS-TRACK
SPREAD OF 45 NM AT TAU 24 AND 120 NM AT TAU 48. NAVGEM IS THE
WESTERNMOST TRACKER AND KEEPS THE SYSTEM SOUTHEAST OF IWO TO BY
MORE THAN 270 NM, LEADING TO HIGH CONFIDENCE THAT THE ISLAND WILL
REMAIN OUTSIDE OF THE GALE-FORCE WIND FIELD. THE FORECAST TRACK IS
SIMILAR TO THE PREVIOUS, SHIFTING 20-30 NM NORTHWARD AT TAU 96 AND
120. THE ECMWF, HAFS-A, AND EXPERIMENTAL AI MODELS COMPRISE THE
TIGHTEST GROUPING AND ARE CLOSEST TO THE JTWC FORECAST TRACK.
NAVGEM, GALWEM, AND THE UKMET MODELS SPAN THE POLEWARD SIDE OF THE
GUIDANCE ENVELOPE, WHILE HWRF AND GFS ARE ON THE EQUATORWARD SIDE.
THE INTENSITY FORECAST THROUGH TAU 24 IS SET HIGHER THAN ALL BUT
THE EXPERIMENTAL AI MODELS AND ECMWF, WHICH APPEAR TO BETTER HANDLE
THE RECENT DEVELOPMENT OF TY 04W. COAMPS-TC WEAKEN THE SYSTEM BY 30 
KTS IN THE NEXT 12-24 HOURS, WHICH IS DEEMED UNREALISTIC. THE FORECAST 
IS THEN PLACED CLOSER TO THE CONSENSUS FROM TAU 48 TO TAU 96 AND THEN 
ALIGNS MORE CLOSELY WITH GFS AS THE SYSTEM BECOMES EXTRATROPICAL.

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


 

Platform: RCM-3
Acquisition Date: 2026-04-14 20:03:32 UTC
Storm Name: WP042026 / SINLAKU
Storm ID: WP04
Storm Center Longitude: 145.392
Storm Center Latitude: 15.286
Incidence Angle (Degrees): 51.014
Quadrant 1 NE VMax (kts): 106.68
Quadrant 2 SE VMax (kts): 101.70
Quadrant 3 SW VMax (kts): 107.56
Quadrant 4 NW VMax (kts): 110.41
RMax (nmi): 19.00 - 21.00

 

TPPN10 PGTW 150854 

A. TYPHOON 04W (SINLAKU)

B. 15/0830Z

C. 15.99N

D. 144.78E

E. FIVE/GK2A

F. T5.0/5.5/W1.0/24HRS  STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 34A/PBO LARGE EYE/ANMTN. WMG EYE SURROUNDED BY MG 
YIELDS AN E# OF 4.5. ADDED 0.5 EYE ADJUSTMENT FOR LG, TO YIELD A DT 
OF 5.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS:
   15/0309Z  15.73N  144.97E  ATMS


   RUCKER