WDPN31 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.2N 135.7E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 473 NM EAST-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT
CONVECTION THAT HAS BUILT OVER THE LOW-LEVEL CIRCULATION CENTER
(LLCC) OVER THE LAST SIX HOURS WITH A BAND OF MOIST DEEP CONVECTION
WRAPPING AROUND THE NORTHEASTERN SIDE. TO THE SOUTHWEST, A SHARP
BAND OF SUBSIDENT DRY AIR INTERCEPTS THE TROPICAL STORM (TS) CORE
FROM A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL POSITIONED TO
THE WEST. ADDITIONALLY, THE TUTT CELL CONTINUES TO INDUCE MODERATE
10-15KT VERTICAL WIND SHEAR WEARING AT THE SYSTEM VORTEX, ACCORDING
TO CIMSS WIND SHEAR ANALYSIS. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE ANIMATED MSI AND DEFINED LOW-LEVEL
CLOUD BANDING WRAPPING INTO THE OBSCURED LLCC. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
EARLIER 130402Z GCOM W1 AMSR2 WIND SPEED DATA REVEALING 35-40KT
WINDS IN THE NORTHERN SEMICIRCLE OF THE CIRCULATION AND IS
SUPPLEMENTED BY THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: AMSR2 WIND SPEED DATA

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 44 KTS AT 130530Z
   CIMSS ADT: 37 KTS AT 130630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE TRACK AND INTENSITY FORECAST
REMAINS CONSISTENT WITH THE PREVIOUS WARNING; HOWEVER, AN ALTERNATE
SCENARIO MAY EXIST WHERE CONTINUED EXPOSURE TO THE TUTT CELL TO THE
WEST MAY INHIBIT RE-INTENSIFICATION THROUGHOUT THE FORECAST.

FORECAST DISCUSSION: TROPICAL STORM (TS) 14W WILL REMAIN UNDER THE
STEERING INFLUENCE OF THE STR TO THE NORTH, DRIVING THE SYSTEM IN A
NORTHWESTWARD DIRECTION THROUGH THE END OF THE FORECAST AS IT
ROUNDS THE RIDGE. LANDFALL IS EXPECTED BETWEEN TAU 48-72. THE
OVERALL TRACK SPEED IS ENHANCED BY THE TUTT CELL PROPELLING THE
CIRCULATION IN THE SAME NORTHWESTWARD DIRECTION AS THE STR, BUT AS 
THE CELL PERMEATES WEST THE INTERACTION WILL DECREASE IN THE LATE-
TERM FORECAST RESULTING IN SLOWER TRACK SPEED. THE INTENSITY FORECAST 
IS HIGHLY DEPENDENT ON THE INTERACTION AND PROXIMITY TO THE TUTT 
CELL, BUT AT THIS TIME THE INTERACTION IS EXPECTED TO DECREASE OVER 
THE NEXT 24 HOURS. WHILE ENTERING IN AN INCREASINGLY FAVORABLE 
ENVIRONMENT, THE SYSTEM WILL REMAIN IN WARM 29-30KT SEA SURFACE 
TEMPERATURES, FAVORABLE UPPER-LEVEL DIVERGENCE, AND DECREASING 
VERTICAL WIND SHEAR ALLOWING FOR GRADUAL RE-INTENSIFICATION TO A PEAK 
OF 70 KTS BY TAU 48, POSSIBLY REACHING 75KTS BETWEEN TAU 24-48 AND 
DEGRADING JUST PRIOR TO TAU 72 DURING LANDFALL.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT REGARDING THE STORM TRACK WITH THE EXCEPTION OF UKMET AND
THE UKMET ENSEMBLE WHICH DEPICT AN OUTLYING SCENARIO WHERE THE
SYSTEM TRACKS NORTHWARD INTO THE YELLOW SEA. BOTH ECENS AND GEFS
ENSEMBLE SOLUTIONS CONFIDENTLY TRACK NORTHWARD OF OKINAWA CLOSER TO
AMAMI OSHIMA, BUT IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT
OKINAWA MAY FALL WITHIN THE 35KT WIND RADII IF THE SYSTEM TAKES THE
SOUTHERNMOST ROUTE OF THE ENSEMBLE SOLUTIONS. THE JTWC INTENSITY
GUIDANCE INCREASES THE INTENSITY FORECAST TO MEDIUM IN THE NEAR-TERM 
FORECAST WITH GFS, HAFS-A, AND ICON REACHING A PEAK OF
70KTS BY TAU 48. 

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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