WDPN31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.8N 151.4E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 480 NM EAST-SOUTHEAST OF GUAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS RAPIDLY
DEVELOPING SPIRAL BANDS OF DEEP CONVECTION TIGHTLY WRAPPING INTO A
FULLY OBSCURED LOW-LEVEL CIRCULATION CENTER OF TYPHOON (TY) 04W
(SINLAKU). ANALYSIS REVEALS HIGHLY FAVORABLE AND SUPPORTIVE
ENVIRONMENT, CHARACTERIZED BY WARM (28-29 C) SEA SURFACE
TEMPERATURES (SST), DEEP ATMOSPHERIC MOISTURE, LOW (5-10 KTS)
VERTICAL WIND SHEAR AND ROBUST RADIAL OUTFLOW. EXHAUST MECHANISM IS
FURTHER ELEVATED BY AN UPPER-LEVEL CENTERED TO THE NORTHEAST OF THE
SYSTEM, AND A NEAR-EQUATORIAL RIDGE (NER) POSITIONED TO THE EAST. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
VISIBLE IMAGERY SHOWING A CENTRAL CONVECTION CONVERGENCE AREA
ASSOCIATED WITH THE LLCC, WHILE THE INITIAL INTENSITY OF 80 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON STRONG CONGRUENCE BETWEEN
THE OBJECTIVE INTENSITY AIDS AND THE AGENCY DVORAK ESTIMATES LISTED
BELOW, OFFSET BY A LACK OF SATELLITE MEASURED WIND SPEED DATA.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 76 KTS AT 110330Z
   CIMSS ADT: 79 KTS AT 110540Z
   CIMSS AIDT: 79 KTS AT 110540Z
   CIMSS D-MINT: 74 KTS AT 110550Z
   CIMSS D-PRINT: 82 KTS AT 110610Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG 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: WHILE THE STEERING MECHANISM IS CURRENTLY
WEAK, RESULTING IN VERY SLOW TRANSLATIONAL SPEEDS, THE NER CENTERED
TO THE SOUTHEAST IS EXPECTED TO DEVELOP A NORTHWARD PROPAGATING
EXTENSION, EVENTUALLY ASSUMING PRIMARY STEERING. AS A RESULT, TY
04W IS FORECAST TO STEADILY PICK UP SPEED, WHILE TRACKING GENERALLY
NORTHWESTWARD TOWARDS THE SOUTHERN MARIANA ISLANDS. WITH THE
ENVIRONMENT REMAINING HIGHLY FAVORABLE FOR RAPID INTENSIFICATION,
TY SINLAKU IS FORECAST TO REACH A PEAK OF 125 KTS AROUND TAU 48,
AHEAD OF THE FINAL APPROACH TOWARD THE ISLAND CHAIN. GIVEN THE
IMPRESSIVE WIND FIELD SIZE, THE 34 KT WIND RADII WILL BE IN REACH
OF THE MARIANAS BETWEEN TAUS 36 AND 48. AROUND TAU 72, TY 04W IS
EXPECTED TO BEGIN ITS RECURVATURE MOTION AROUND THE SOUTHWESTERN
PERIPHERY OF THE BUILDING EXTENSION OF THE NER. THE SYSTEM IS
EXPECTED TO START WEAKENING AT THAT POINT, GIVEN SLOWLY INCREASING
VERTICAL WIND SHEAR.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
AGREEMENT IN REGARD TO THE GENERAL STEERING PATTERN AND THE
RECURVATURE SCENARIO, AND WHILE THE CROSS-TRACK SPREAD AMONG THE
CONSENSUS MEMBERS HAS IMPROVED, IT IS STILL RATHER SIGNIFICANT AT
185 NM FOR TAU 72. AS SUCH, THE OFFICIAL JTWC FORECAST IS ASSESSED
WITH MEDIUM CONFIDENCE AND IS LAID CLOSE TO THE MULTI-MODEL
CONSENSUS. PRIMARY OUTLIERS REMAIN UKMET DETERMINISTIC AND GALWEM
PREDICTING TRACK NORTHEAST OF TINIAN, WHILE THE REMAINING MODELS
ARE CONTAINED WITHIN A 90 NM CROSS-TRACK ENVELOPE ENCOMPASSING AREA
SOUTHWEST OF GUAM AND THE ISLAND OF ROTA. OVER THE LAST SEVERAL
MODEL RUNS, ALL AVAILABLE GUIDANCE APPEARS TO BE CONVERGING WITHIN
AN AREA BETWEEN GUAM AND ROTA. IN REGARD TO INTENSITY, JTWC
FORECAST IS LAID CLOSE TO THAT OF HAFS, AND JUST ABOVE THE MULTI-MODEL 
CONSENSUS, WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD. 
WHILE 
GLOBAL DETERMINISTIC AND STATISTICAL-DYNAMICAL MODELS ARE MORE 
CONSERVATIVE, WITH PEAK INTENSITIES AROUND 95-115 KTS, SEVERAL RAPID 
INTENSIFICATION AIDS ARE INDICATING MAXIMUM WINDS REACHING 135+ KTS. 
HAFS IS PREDICTING A PEAK OF 125 KTS AT TAU 48, CONSISTENT WITH THE 
OFFICIAL JTWC ASSESSMENT.

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