WDPN31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.8N 141.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 635 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
UPPER-LEVEL CONDITIONS APPEAR TO BE IMPROVING AS INDICATED IN 
ANIMATED WATER VAPOR IMAGERY, WHICH SHOWS EXPANDING WESTWARD OUTFLOW 
IN ADDITION TO ROBUST EASTWARD AND EQUATORWARD OUTFLOW. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS LOW-LEVEL CLOUD LINES 
WRAPPING INTO A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER 
(LLCC), WHICH HAS NOW TUCKED UNDER AN AREA OF INTENSE EXPANDING DEEP 
CONVECTION. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS 
CYCLONICALLY ROTATING VORTICAL HOT TOWERS, WITH CLOUD TOP 
TEMPERATURES OF ABOUT -87C, OVER THE EASTERN PERIPHERY OF THE LLCC. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI 
AND A 120651Z GMI 37GHZ COLOR COMPOSITE MICROWAVE IMAGE, WHICH 
REVEALS A DEFINED LLCC, WITH CURVED BANDING OVER THE SOUTHERN 
QUADRANT WRAPPING INTO THE NORTHERN QUADRANT. THE INITIAL INTENSITY 
OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE KNES AND 
PGTW DVORAK ESTIMATES AS WELL AS SURFACE OBSERVATIONS FROM IWO-TO,
WHICH PEAKED AT 120449Z AT 27G41KTS (10 MINUTE SUSTAINED WINDS). WIND 
DIRECTION HAS SUBSEQUENTLY SHIFTED TO THE NORTHWEST AS THE LLCC 
TRACKED OVER AND JUST EAST OF IWO-TO BY 120651Z AS SUPPORTED BY THE 
AFOREMENTIONED GMI IMAGE. THE CIMSS OBJECTIVE AIDT AND SATCON 
ESTIMATES ALSO SUPPORT THE INITIAL INTENSITY ASSESSMENT. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTH-SOUTH ORIENTED LOW- TO MID-LEVEL
SUBTROPICAL RIDGE (STR) ENTRENCHED EAST AND NORTHEAST OF THE
SYSTEM. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 38 KTS AT 120419Z
   CIMSS ADT: 32 KTS AT 120530Z
   CIMSS AIDT: 36 KTS AT 120530Z
   CIMSS D-MINT: 25 KTS AT 120419Z
   CIMSS D-PRINT: 27 KTS AT 120600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 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: TROPICAL STORM (TS) 06W IS NOT VERTICALLY
ALIGNED BUT APPEARS TO BE CONSOLIDATING AS INDICATED IN MSI AND
MICROWAVE IMAGERY. THIS HAS LED TO SOMEWHAT ERRATIC SHORT-TERM
TRACK MOTION AS THE LOW-LEVEL AND UPPER-LEVEL CIRCULATION CENTERS
BECOME BETTER ALIGNED. THE PRESENCE OF VORTICAL HOT TOWERS IN
CONJUNCTION WITH THE EXPANDING WESTWARD OUTFLOW AGAINST THE
UPPER-LEVEL NORTHWESTERLY VERTICAL WIND SHEAR MAY POSSIBLY BE
SIGNALING A PERIOD OF RAPID INTENSIFICATION AS THE VORTEX BECOMES
INCREASINGLY AXISYMMETRIC. AS THIS OCCURS, THE SYSTEM IS FORECAST
TO TRACK IN A MORE CONSISTENT POLEWARD TRAJECTORY ALONG THE WESTERN
PERIPHERY OF THE STR THROUGH TAU 36. AFTER TAU 36, A MAJOR
SHORTWAVE TROUGH IS EXPECTED TO DEEPEN OVER THE KOREAN PENINSULA
AND JAPAN, WHICH COULD LEAD TO A NORTH-NORTHWESTWARD TRACK CLOSER
TO YOKOSUKA BEFORE THE SYSTEM RECURVES NORTH-NORTHEASTWARD TOWARD
THE KURIL ISLANDS. EXTRA-TROPICAL TRANSITION (ETT) WILL COMMENCE AS
THE SYSTEM INTERACTS WITH THE MAJOR SHORTWAVE TROUGH NEAR TAU 48,
WITH ETT COMPLETING BY TAU 72 AS THE SYSTEM BECOMES EMBEDDED WITHIN
THE MIDLATITUDE WESTERLIES AND ACCELERATES.   

MODEL DISCUSSION: BOTH THE DETERMINISTIC VORTEX TRACKERS AND 
ENSEMBLES (GEFS AND ECENS) INDICATE A FAIRLY TIGHT GROUPING OF 
SOLUTIONS THROUGH TAU 36. AFTER TAU 36, THE MODELS DIVERGE INDICATING 
INCREASING UNCERTAINTY. BOTH GEFS AND ECENS SHOW SOLUTIONS SKIRTING 
THE CENTRAL JAPAN TO NORTHEASTERN JAPAN COAST, WITH THE BULK OF 
SOLUTIONS CONCENTRATED OFF THE COAST OF HONSHU. THIS PHASE OF THE 
FORECAST TRACK CARRIES THE GREATEST UNCERTAINTY. THEREFORE, TRACK 
SHIFTS CLOSER TO HONSHU OR SKIRTING THE EASTERN COAST ARE POSSIBLE. 
ADDITIONALLY, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY 
FORECAST, WITH UNCERTAINTY IN THE PEAK INTENSITY. COAMPS-TC (GFS) 
SHOWS A PEAK OF 63 KNOTS AT TAU 36 WHILE HAFS-A SHOWS A PEAK OF 59 
KNOTS.      

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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