WDPN31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.4N 139.7E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 336 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
CONVECTIVE BANDING WRAPPING TIGHTLY INTO A VORTEX CENTER. DRY AIR AND 
15-20KTS OF VERTICAL WIND SHEAR FROM A TROPICAL UPPER TROPOSPHERIC 
TROUGH (TUTT) CELL INTRUDE INTO THE CENTER OF THE CIRCULATION FROM 
THE NORTHWEST, ACTING AS AN INHIBITOR TO RAPID INTENSIFICATION. 
ALTERNATIVELY, THE TUTT CELL IS ENHANCING UPPER-LEVEL OUTFLOW 
POLEWARD WHICH SUPPORTS THE GRADUAL INTENSIFICATION ALONGSIDE WARM SEA 
SURFACE TEMPERATURES 29-30C TO OVERCOME THE MODERATE VERTICAL WIND 
SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
ANIMATED MSI DEPICTING THE CIRCULATION CENTER. THE INITIAL INTENSITY 
OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: BETWEEN A NEAR EQUATORIAL RIDGE (NER)
POSITIONED TO THE SOUTHEAST AND A SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 59 KTS AT 120700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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: TROPICAL STORM (TS) 14W WILL NO LONGER BE
UNDER THE STEERING INFLUENCE OF THE NER TO THE SOUTHWEST AS IT 
CONTINUES TO MOVE AWAY AND WILL TRACK NORTHWESTWARD WHILE DRIVEN BY A 
STR TO THE NORTH THAT EXTENDS FROM THE KOREAN PENINSULA TO THE EAST 
OF JAPAN THROUGH THE FIRST 48 HOURS OF THE FORECAST BEFORE ALTERING 
COURSE WEST-NORTHWESTWARD STEERED BY AN EXTENSION OF THE STR THROUGH 
THE END OF THE FORECAST PERIOD. WHILE TRACKING NORTHWESTWARD THE 
SYSTEM WILL INTENSIFY GRADUALLY FOR THE FIRST 36 HOURS DUE TO 
FAVORABLE SEA SURFACE TEMPERATURES OF 29-30C AND STRONG POLEWARD AND
EQUATORWARD OUTFLOW, HOWEVER THE RATE OF INTENSIFICATION IS
DAMPENED BY THE CLOSE PROXIMITY OF THE TUTT CELL TO THE NORTHWEST.
THE TUTT CELL IS EXPECTED TO DRIFT TO THE WEST-SOUTHWEST AWAY FROM
TS 14W AND THE STORM TRACK, ALLOWING THE CONDITIONS TO BE FAVORABLE
FOR RAPID INTENSIFICATION AS THE SYSTEM PASSES APPROXIMATELY 100NM
NORTH OF OKINAWA TO A PEAK OF 105KTS BY TAU 72. TS 14W WILL MAKE
LANDFALL BETWEEN TAU 72-96, RESULTING IN RAPID WEAKENING AND DRY
AIR CUTTING OFF THE FUEL SOURCE TO THE SYSTEM AS IT CONTINUES
DISSIPATING INLAND.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TS 14W WILL TRACK NORTHWESTWARD FOR THE FIRST 48 HOURS OF THE
FORECAST BUT DECREASES CONFIDENCE AFTERWARDS. THE CROSS-TRACK
SPREAD OPENS AFTER TAU 48 TO 608NM BY THE END OF THE FORECAST DUE TO 
DIFFERENT INTERPRETATIONS OF HOW STRONG THE EXTENSION OF THE STR TO 
THE NORTH IS AND HOW FAR TO THE WEST IT EXTENDS. THE DIFFERENCES ARE
REFLECTED BETWEEN GFS AND GEFS AS THE DETERMINISTIC MODEL TRACKS
WEST-NORTHWESTWARD BUT THE ENSEMBLE MEAN CONTINUES IN A
NORTHWESTWARD DIRECTION. THE GEFS AND ECENS ENSEMBLES ALSO SHOW A
SPREAD OF SOLUTIONS, ABOUT THIRD TO A HALF, CLOSER TO OKINAWA,
ALLOWING FOR A SLIGHT POTENTIAL FOR A TRACK FARTHER SOUTH. THE MEAN
TRACK OF ECENS IS SLIGHTLY NORTH OF OKINAWA AND LIES VERY CLOSELY
TO THE JTWC TRACK. THE INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT
THE SYSTEM WILL SLOWLY INTENSIFY OVER THE COURSE OF THE FIRST 36
HOURS BEFORE THE TUTT CELL MOVES AWAY AND ALLOWS FOR FAVORABLE
CONDITIONS WITH LOW SHEAR AND HIGHER MOISTURE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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